6 anos = 2160 dias = 51840 horas = 3110400 minutos = segundos. Show
Quantos dias tem 5 anos e 6 meses?Resposta. Considerando que em um ano há 365 dias, 5 anos possuem dias. Considerando que em um mês há 30 dias, 6 meses possuem dias. Portanto, em 5 anos e 6 meses, há dias. Quantos meses tem 5 anos e meio?Anos em Meses
Quanto equivale 5 anos?R) 5 anos correspondem a 60 meses. Quantos dias meses e anos?TABELA PARA CONVERSÃO DE ANOS E MESES EM DIAS
Como converter data em dias?Exemplo
Como calcular meses a partir de uma data?Vamos inserir a função =DATADIF(C4;C5;"ym") e o Excel retornará o número de meses inteiros entre as duas datas. Veja que de 5 de Outubro a 3 de Março tem 4 meses completos, por isso ele retorna o valor 4. Como calcular tempo a partir de uma data no Excel?Selecione a célula B4 e, na guia Página Inicial, escolha AutoSoma. A fórmula terá a seguinte aparência: =SOMA(B2:B3). Pressione Enter para obter o mesmo resultado, 16 horas e 15 minutos. Como calcular os dias entre uma data e outra no Excel?Para calcular o intervalo entre duas datas, selecione duas células da planilha e insira as datas desejadas nelas. Para inserir a data presente de forma automática, utilize a fórmula =HOJE() porém sem preencher os parâmetros (valores entre parênteses após a fórmula). Como calcular diferença de dias entre duas datas?Para calcular os dias desse exemplo você deve realizar o seguinte cálculo: 1 ano= 365 dias; 2 meses = entre 60 à 61 dias, a depender do mês....Sendo assim, você deve calcular a diferença entre ano, mês e dia:
Como colocar data no Excel automática?Inserir uma data ou hora estática em uma célula do Excel Quando você pressiona uma combinação de teclas como Ctrl+; para inserir a data atual em uma célula, o Excel “tira um instantâneo” da data atual e insere a data na célula. Como o valor dessa célula não muda, ele é considerado estático. Como programar o Excel para informar sobre uma data vencida?Primeiramente, você deve fazer a seleção do intervalo de datas que deseja fazer a formatação. Em seguida, você deve ir até Formatação Condicional, Regras de Realce de Células e escolher a opção Uma data que ocorre... Portanto, note que o Excel nos mostra uma caixa de diálogo onde devemos escolher a opção desejada. Como transformar uma data em texto no Excel?Visão geral
Tem como transformar números em texto no Excel?Formatar números como texto
Como colocar mês em texto no Excel?Nome do mês por extenso no Excel com a função Escolher
Como escrever um número por extenso no Excel?Expanda a célula B1 onde os valores por extenso serão escritos. Selecione a célula B1 e clique no ícone fx; A seguir na janela - Inserir função - selecione a opção - Definida pelo usuário - e escolha a macro Extenso_Valor; Na caixa argumentos da função informe a célula onde os valores numéricos serão digitados. Como fazer o Word escrever números por extenso?Veja nessa dica como fazer isso. Agora, basta pressionar novamente a tecla F9 e o valor será atualizado e aparecerá por extenso na tela (no caso, mil cento e vinte e oito). Para alterar o número, pressione o atalho Ctrl + F9 e digite um novo valor e aperte F9 para atualizar o resultado. Como escrever em uma planilha excel?O que é Excel: Excel é uma palavra da língua inglesa em que o verbo to excel significa sobressair, superar os outros em boas qualidades. Deriva do Latim “excellere” (subir, ser eminente) onde “ex” significa “para fora de” e “cellere” significa “lugar alto, torre”. O que é uma célula de uma planilha?Célula. O elemento indicado pelo cruzamento entre uma linha e uma coluna chama-se célula. Células são o componente elementar de uma planilha eletrônica. Toda a informação, como valores e fórmulas, deve ser colocada em alguma célula para poder ser utilizada. Page 2
TABLA XIX.-Frecuencia relativa de la dirección del viento en la Habana.
Velocidad del viento en kilómetros. Media diaria para cada mes de 41 años.
En la Tabla XIX puede verse la frecuencia relativa de las diferentes direcciones observadas en cada mes y en el año. En su formación se han utilizado las observaciones bihorarias durante 11 años consecutivos, y las cifras expresan el número de veces que está anotada una dirección determinada, puesta en la primera columna, por cada mil observaciones hechas. Al pié de la misma tabla se pone el promedio diario de la velocidad del viento en kilómetros para cada mes y para el año, sacado de 41 años (1874-1914). Los números expresan el promedio diario del recorrido total del viento en kilómetros. Lo primero que salta a la vista es el gran predominio de los vientos comprendidos en el cuadrante entre el N. y E. ambos incluidos. De todas las demás direcciones sólo hay una al SE. que llegue a reinar 100 veces de 1,000 observaciones, y sólo en el mes de septiembre con 119.7. Las restantes están representadas por números bajos, de modo que las cinco direcciones citadas suman un contingente mucho más alto que las once restantes juntas. En estos se ven números aun inferiores a 5 por 1,000, 4 por 1,000 y aun 3 por 1,000. Al primer cuadrante le sigue en frecuencia relativa de los vientos el segundo, siendo el tercero el menos frecuentado. Si el régimen dominante de los vientos es del primer cuadrante cuanto a su dirección, todavía lo es más cuanto a su recorrido o velocidad. Hablando de condiciones normales del tiempo, cuando no interviene la influencia de alguna perturbación ciclónica, en los meses de verano el recorrido total del día le pertenece casi entero al primer cuadrante y solo una pequeña fracción al segundo. Según hemos dicho la brisa del mar que sopla casi todo el día alcanza de 5 a 8 metros por segundo, y la brisa de tierra que reina de noche y algunas de las primeras horas de la mañana, es tan débil que los anemómetros apenas se mueven, y con mucha frecuencia se paran del todo o están irresolutos parándose varias veces en una sola revolución. Las direcciones del tercero y cuarto cuadrantes son generalmente debidas a condiciones anormales del tiempo, y por eso cuando reina alguna de esas direcciones suele adquirir más velocidad. Cuanto a las velocidades excepcionales al paso de los huracanes es difícil determinarlas con precisión. Cuando el viento alcanza su apogeo en las rachas Page 3
The CHAIRMAN. If there is no further discussion we will pass to the next paper on the program, “The Pleionian fluctuations of climate,” by Dr. Henryk Arctowski, of the New York Public Library.
THE PLEIONIAN CYCLE OF CLIMATIC FLUCTUATIONS.
By HENRYK ARCTOWSKI,
As we observe changes of weather from one day to another so we observe climatic fluctuations from one season to another, from one year to the following year. Persistency of given weather conditions may frequently be observed. In the case of climatic fluctuations also there may be a series of years abnormally dry or abnormally rainy, or we may have groups of years offering some other particularities, such as a late spring, for example, or an unusually warm winter, and such exceptional conditions reoccurring for a succession of years give the impression of a radical change of climate. In reality, therefore, we may consider the study of these changes or fluctuations just as important and as having a far more practical value than the study of the so-called normal climatic conditions. Considering 10 yearly means of atmospheric temperature as representing quasi-normal values, I inscribed the annual departures from these means on maps. For each year so far taken into consideration the departures are never positive all over the world or negative. In each case some regions are characterized by an excess of heat, whereas in other regions temperature is in deficiency. The areas of positive departures have been called thermopleions and those of negative departures antipleions. The antipleions do not necessarily compensate the thermopleions. The year 1900, for example, was a year of an excess of pleions, and the year 1893 was a year of deficiency of pleions. The difference of the world's temperature for such exceptional pleionian and antiplesonian years may reach 0.5° C., or perhaps even more. Taking barometric measurements into consideration, one also finds that for each year some centers of abnormally high and abnormally low atmospheric pressure are conspicuous. These baropleions and antibaros displace themselves from year to year and evidently influence atmospheric circulation very greatly. These changes must have an effect on the distribution of the frequency of storms and on rainfall. Of rainfall data I have studied extensively the ombropleions observed in Europe during the years 1851-1905. In order to investigate these phenomena more thoroughly the monthly means of temperature, atmospheric pressure, rainfall, sunshine duration, and thunderstorm frequency have been taken into consideration and the changes from one year to another have been studied by the method of overlapping means. Among other results it was found that at many stations, particularly in Equatorial regions, temperature rises or falls practically simultaneously, and that the pleions disappear and reappear more or less periodically at intervals of two to three years. The records of the Harvard Observatory station at Arequipa, in Peru, have been taken as a standard of the occurring pleionian Page 4
Speaking of heat, it would also be preferable to avoid that expression entirely and use the words radiation, or energy, or radiant energy of the sun. But all such objections have nothing in common with the fact of the existence of a hormepleionian variation-a fact which is a result of the Greenwich measurements and of my calculations. And now, in order to establish a theory of the terrestrial pleionian fluctuations, more calculations are necessary. The first effort to be made is to try to demonstrate that atmospheric temperature varies proportionally to the ratio of the faculæ and umbræ, or, if such a law can not be established, because of the complexity of meteorological phenomena, it will be necessary to show at least some striking correlations between the variations of one and the other. Up to the present a lack of time has prevented me from making more than one single attempt, which has been successful, and I wish to show you now how the hormepleionian maximum of the solar rotations 772–781 found its repercussion in the temperatures observed on our earth surface during the years 1911 and 1912. In order to have figures corresponding exactly to the same time intervals as those of temperature, monthly means of the areas of faculæ and umbræ were calculated for the years 1909 to 1913, and then the ratios of the overlapping yearly totals were formed. These figures expressed graphically on a diagram show a well-pronounced crest of the hormepleion corresponding to the mean of June, 1911, to May, 1912. But before this maximum is reached we notice two steps-one at the mean of April, 1910, to March, 1911, and the other corresponding to the mean of November, 1910, to October, 1911. In 1912 the ratios decrease till a minimum corresponding to the mean of March, 1912, to February, 1913, is reached, and from then on the ratios increase and form the ascending branch of a dew hormepleion. To simplify comparisons, we may call 1911: 2 the mean of February, 1911, to January, 1912; 1911:3, that of March, 1911, to February, 1912, and so forth. The figures for 1910:4, 1910:11, 1911: 6, and 1912:3 are therefore conspicuous. For the same years, 1909–1913, I dispose at present of more than 150 curves of overlapping temperature means of stations from all parts of the world. This amount of already computed data is very respectable, but, of course, I am anxious to obtain more data, and I do not think that the difficulties one encounters in collecting the results of meteorological observations made in some countries or the shocking mistakes that may be found in the tabulations of official publications of some other countries will prevent me from trying to make my research as thorough as possible. If my reasoning is correct, it follows that at the time of the occurrence of the hormepleion maximum of 1911:6, or shortly afterwards, we should observe thermopleionian crests on the curves of overlapping means of the observed temperatures. Or since it has been found that in no case studied so far temperature was above the average all over the world, that, on the contrary, antipleions always compensate the pleions, more or less, it will be necessary to find at least a predominance of thermopleions synchronal with the solar maximum. And so it seems to be. of the records studied so far I may say that an abnormal increase of temperature during the latter part of 1911 and in 1912 is a striking feature of the curves of meteorological stations in Alaska, British Columbia, Vancouver Island, Oregon, and to a certain extent California; then of Mexico, Panama, the West Indies, and Bahamas, British and French Guiana, Matto Grosso, Parana, Peru; the Faroe Islands, Holland, northern Germany, Switzerland, Italy, Gibraltar, Algeria, Morocco, the Canary Islands; the Sahara, Egypt; Page 5
the meteorological observations upon the Wilkes and Ross exploring expeditions to the southern seas. Later observations have confirmed the diminishing atmospheric pressures lo the higher latitudes of the southern hemisphere up to the points visited at the time Fcrrcl's deductions were made. It was through inferring without warrant that pressures continue to diinioish at the same rate beyond the liinits of observation that Ferrel fell into error-a failing which has been, and still is, comnion among men of science even of the highest rauk. An entirely similar error within the field of meteorology was made by no less an authority than Helmholtz, who, tacitly assuming that the thermic gradient determined for the lower atmosphere continues upward without change beyond the range of our observations, declared that the absolute zero of temperature would be found at an altitude of 28 kilometers, whereas subsequent investigation has revealed the fact that the convective zone of the atmosphere ends at an altitude ranging from 18 to 9 kilometers according to latitude, and that this zone is overlaid by one that is essentially isothermal. What a lesson, if we will but heed it, for those of us who instead of directing our thoughts to the temperatures above our heads, have turned them downward in the direction of the eartli's center. We have to-day a crude temperature scale which reaches downward about one four-thousandth of the distance to the goal whose temperature we seek to learn; and yet one may read learned disquisitious upon the temperature of the earth's core, including refined corrections. The theoretic polar cyclone, or circumpolar whirl, of Ferrel was a different conception from that of the normal cyclone, since the movement of air within the vortex was supposed to be directed downward toward the earth's surface, it being essential to his theory that the air which had traveled from the equatorial regions toward the poles at high levels should in some manner be retained within the circulatory system. Though contrary to the idea of the cyclone, there was no other recourse than to bring the air down to the surface in the polar regions. To-day without essential modifications this theory of polar calms surrounded by a whirl of westerly winds has been embodied in standar texts upon meteorology and has been defensively argued by Hann and Meinardus against the encroachments of observations now available from the polar regions. As late as 1897 Hann declared : “ The whole Antarctic circumpolar area presents us, as already stated, with a vast cyclone, of which the center is at the pole, while the westerly winds circulate around it.” His view, an adoption of Ferrel, was of course speculative, and when Bernacchi of the Southern Cross expedition had brouglit out on the basis of observations made at Cape Allare the evidence for anticyclonic conditions over the south polar regions, Hann cautiously qualified his earlier statemeuts in the following maner: As regards the Antarctic anticyclone, I have certainly not expressed myself quite clearly in my Klimatologie, as you very fairly point out. It is certain that an area of pressure, which is higher than that of the surrounding area, lying over a chillel continent, or over any considerable land area, can coexist with a great polar cyclone, for instance, around the South I'ole. The very low temperature can produce in the lower strata of the atmosphere a pressure higher than its environments. The anticyclone, however, must be very shallow, and at a moderate elevation the ordinary circulation of the atmosphere must reestablish itself. * * It is just possible that farther inland a slight increase of pressure might be observable. There is certainly no chance of the existence of a real continental anticyclone, inasmuch as at Cape Adlare the barometer fills from summer to winter,
· Letter written to Capt. R. F. Scott in 1900, The Antarctic Manual, 1901, p. 34. Page 6
companied by abnormality of climate, the normal climate being a uniform one without zonal differentiation. These generalizations concerning the climatolog. ical criteria offered by the fossil floras are as follows: 1. “ Relative uniformity, mildness (probably subtropical in degree) and comparative equability of climate, accompanied by a high humidity, hare prevailed over the greater part of the earth, extending to, or into, the Polar circles, dur. ing the greater part of geologic time since, at latest, the Middle Paleozoic, This is the regular, the ordinary, the normal coudition. From a broad point of view these conditions are relatively stable. 2. “The development of strongly marked climatic zones, at least between the polar circles, is exceptional and abnormal. It is usually confined to short intervals, or to intermittently oscillating short intervals, all within relatively short periods. 3. “The periods of abnormal climatic differentiation are characterized by the derelopment of extremesmi. e., by extreme and abnormal heat or cold (glaciation), humidity or aridity-wbich are local or regional in their occurrence and variable or unstable. 4. “ The brief geological period in which we live is a part of one of the most strongly developed and unstable of these abnormal intervals of radical change. The assumption that climatic variations, contrasting extremes, and complexity of combination and geographic distribution of climatic factors, such as now exist, are normal or essential, and that they were present also, though in slightly less degree, in all geological periods, appears to be without paleobotanical warrant. The proposition that we are still in the glacial epoch is paleontologically true. We have no evidence that in any other post-Silurian, with perhaps the exception of the Permo-carboniferous glacial period, hare the climatic distribution and segregation of life been so highly differentiated and complicated as in post-Tertiary time. 5. “The distribution and characters of most of the pre-Tertiary Noras show that time and again during the great periods of relative uniformity and equable mildness, plant associations were able to pass from one high latitude to the opposite without meeting an efficient climatic obstruction in the equatorial region. The unchanged features of the species and the grouping of the latter show that the climatic elements of the environment must have been similar throughout the range of the flora. Therefore it arepars that a climate essentially the same must have continued from one latitude to the other without the interposition at those periods of a torrid equatorial zone. The absence of the latter may also be inferred from the relative uniformity of distribution in other directions, as shown by the remarkable east-west and radial ranges of the fioras. 6. "The development and existence of torridity-i. c., of a torrid zone in the equatorial belt or any other great region of the earth-is concomitant and casually connected with the development of regional frost. It would appear that the occurrence of a torrid zone is peculiar to abnormal or glacial intervals." By this series of generalizations an interesting light is thrown upon the making of scientific theories, to which we have already adverted early in this paper. Living as we do in one of the brief abnormal climatic periods of the earth's history, it was inevitable that our pictures of past geological timo should be colored to accord with those with which we are familiar from our own experiences, and to rid ourselves of such preconceived notions is alwars a difficult matter. It is, we believe, an important contribution to have shown that the study of existing continental glaciers has supplied the esplanation for the conditions from the revealed field of paleobotany. Page 7
The vertical currents are subject to changes of profound interest, because the air in them is subjected to rapid changes of pressure. The actual amount of change varies with the temperature of the air, but it is about 1 pound per square inch for 2,000 feet of vertical distance. Such changes of pressure, de creasing in ascending currents, increasing in descending currents, produce changes of volume and of temperature, according to the laws of Boyle and Charles. An ascending current cools at the rate of 1° F. in 178 feet (1° C. in 100 meters), and descending currents warın at the same rate. Such temperature changes induce corresponding changes of state of the aqueous vapor in the air. Cloudiness and rainfall occur in the ascending current, dryness and clearness characterize the descending current. The latter condition is especially favorable to the passage of radiation, it may be remarked. I have limited the present study to that peninsula formed by upper Michigan and northern Wisconsin between the adjacent lakes, Michigan and Superior, partly because it affords the best esample of the phenomena studied and partly because the data for other regions were not so readily available to me. The lake region lies in the belt of westerly winds, which is kept in continual turbulence by a procession of atmosplieric vortices, cyclonic and anticy. FIG. 1.-Resultant wind movement in Juno, at 7 a.m.(- ►) clonic. It is only at rare and at 7 p. m. (t.........) at lake shore stations. Based on 11 intervals that the land and years observations, 1905–1915. (Author's original illustration.) sea breeze has sole control of the situation. The tendency of the air to circulate between land and water is, however, always present when these surfaces differ in temperature, and at times when it can not control the air movements itself, acts as a deflecting force upon stronger circulatory movements, In order to exhibit the effects of lake influence upon the winds it is necessary to deduce the resultant wind for the day winds and for the night winds separately. This is done by compounding, by the usual rule for vectors, the total movement observed from each of the principal points of the compass. In this process the accidental and variable movements from opposite directions neutralize one another and leave the steady phenomena to be studied. I have done this for the morning and afternoon wind movements in June at Duluth and Marquette, on Lake Superior, and Escanaba, Green Bay, and Milwaukee, on Lake Michigan, and for Madison at a distance of 80 miles from the latter lake, and exhibit the result in figure 1 and in Table 1. The 'observations available to me, those telegraphed for use in preparing the official weather map, are made at 7 a. m. and 7 p. m. in the lake region, not the times of maximum development of the land and sea breeze. I should also have done better to have chosen August or September, since the lakes are generally colder than the land, even at night in June. However, the vectors, which take account of both the direction and velocity of the wind, show clearly the tendency to offshore winds in the morning and onshore winds in the evening, which is as it should be. The effects of local topography and of general atmospheric drift remain in these vectors. Page 8
Consideration of these two diagrams, figures 2 and 3, indicates that the ascending currents over the land are likely to be most active between April and September. In view of the cooling that ensues in ascending currents, heavier rain. fall is to be expected over the land during these months. In order to verify this deduction I have averaged the rainfall for 10 years for these sis months from the tables of rainfall data published in United States Weather Bureau Bulletin W,“ Climatological data by sections," taking for the purpose 68 stations with complete or nearly complete series of observations for the period. The missing data were supplied by interpolation from comparisons with surrounding stations. The result of this investigation is exhibited in figure 4. The excess
FIG. 6.-Average annual rainfall of Wisconsin and Michigan. (From Gannett, Distrh Weather Rosiew, July, 1913.) of rainfall in the interior of the peninsula over that on the lake shores is no less than 12 inches, or 86 per cent of the latter. The winter precipitation, on the other hand, is mostly in the vicinity of the lakes. C. F. Brooks has mapped the snowfall of the lake region, and I copy, in figure 5, a portion of his map. I am not prepared to assign this precipitation to local convectional circulation, although the fact that the land surface is nearly 20° colder than the water surface, which does not freeze in winter, demands that some credit be given this influence. That the summer and winter distributions of precipitation are nearly compensatory is shown by the map of average annual rainfall, figure 6, wherein the maxima are only about 14 per cent higher than the minima. The descending member of the circulation of the air between the land and the lake has effects scarcely less important than those attending the ascending cur. rent when it prevails over the land. Descending currents are induced by the land being colder than the lake. Their descent involves compression of the descending air, so that clouds are usually absent from descending currents. Page 9
Average iclocity of the wind from each dircction, in June, for the period 1905-1915 (milcs per hour). (c) MORNING (7 A. M.).
Papers on the same subject. Davis, T. H. The direction of local winds as affected by contiguous areas of land and water. Monthly Weather Review, 1906. Vol. 34, page 410. Eshleman, C. H. Climatic effect of the Great Lakes as typified at Grand Haven, Mich. Meteorological Chart of the Great Lakes, September, 1913. Washing ton, D. C. U. S. Weather Bureau publication. Hann, J. v. Land- und Seeklima. in Handbuch der Klimatologie, 3 Auf. Stutt gart, 1908. pp. 119–179. Hann, J. y. The influence of continents upon winds, in Handbook of Climatology. Part 1, Chapter IX, pp. 154–180. (Translation by R. De C. Ward.) New York, 1903. Hann, J. v. u. Süring, R. Die Land- und Seewinde, S. 438, and Monsune, S. 453, in Lehrbuch der Meteorologie, Leipzig, 1915. Henry, A. J. Winds of the Lake Region, Monthly Weather Review, Nov., 1907, page 516. Kaiser, Max. The land and sea winds of the Baltic coast of Germany. Review by C. Abbe, in Monthly Weather Review, 1906, Vol. 34, page 460. Townsend, C. McD. Colonel, U. S. Army, Corps of Engineers. The Currents of Lake Michigan and their influence on the Climate of the neighboring States. Paper presented to Western Society of Engineers, Chicago, III, Oct. 11, 1915. Publications consulted in preparing this paper. Brooks, C. F. The snowfall of the United States. Quarterly Journal of the Royal Meteorological Society. 1913, Vol. 39. No. 166, page 81. Brooks, C. F. The snowfall of the eastern United States. Monthly Weather Review, Vol. 43, Pt. 1, January, 1915, page 2. Day, P. C. Frost data of the United States. U. S. Weather Bureau Bulletin V. Washington, 1911. Henry, A. J. Climatology of the United States. U. S. Weather Bureau Bulle tin Q. Summaries of Climatological Data by Sections, U. S. Weather Bureau. Bulletin W. 2 vols. Washington, 1912. (Water surface temperatures of the Great Lakes.) In report of board of officers of Army engineers to consider “Waterway from Lockport, Ill., by way of the Des Plaines River and the Ilinois River to the mouth of the Illinois River." H, R. Document No. 762, 2d session, 630 Congress. Page 10
SESSION OF SUBSECTION B OF SECTION II. CARNEGIE INSTITUTION, Chairman, Charles F. Marvin. The meeting was called to order at 9.30 o'clock by the chairman. The CHAIRMAN. The first paper on the program this morning will be on “ The Climate of Salt Lake City," by A. H. Thiessen, of the United States Weather Bureau, Salt Lake City.
THE WEATHER AND CLIMATE OF SALT LAKE CITY, UTAH.
By ALFRED H. THIESSEN, Meteorologist, United States Weather Bureau, Portland, Oreg. In the eastern portion of the Great Basin lies Utah and Great Salt Lakes, the former being a fresh body of water and the latter, as its name indicates, salt. The Jordan River is the outlet of Utah Lake, flowing in a due north direction to Great Salt Lake, which has no outlet. In the northern part of the Jordan River Valley, more commonly known as the Salt Lake Valley, is located Salt Lake City, Utah. This valley is 28 miles long and 15 miles wide. The Wasatch Mountains form the eastern rim of the valley and rise to elevations varying from 8,000 to 10,000 feet. These mountains curve westward to the lake, and in this curve, sloping to the west and south, lies Salt Lake City. The Oquirrh Mountains lie to the west, but do not extend so far north as the Wasatch, and thus the view to the west and to the lake is unobstructed. The western and lower part of the city lies in the flat, while its northern and eastern portions cover the benches, which are the old beaches of Lake Bonne ville, and are about 200 feet above the lower portion. In figure 1 the lines composed of short and long dashes are divides, and indicate the limits of the Jordan River watershed. The numerous creeks flowing westward from the Wasatch Mountains comprise the water supply to the city. The mountains to the north and east extend nearly to the city limits, while to the west the land is level to the lake, 12 miles away, and to the south as far as the Narrows, 15 miles away. Salt Lake City is situated on about the same parallel as Cheyenne, Wyo.; Omaha, Nebr.; Peoria, Ill.; Pittsburgh, Pa.; and New York, in this country, and Barcelona, Spain; Rome, Italy; and Constantinople, Turkey, in Europe. It varies in elevation from 4,200 to 4,500 feet. The climates of the world are classified as continental, marine, and mountain. Salt Lake City, from its position inland and elevation, has characteristics of the continental and mountain types. The Weather Bureau record at Salt Lake City dates back to 1875. Records were made by private persons previous to that date, but doubt exists as to their accuracy. In the following will be given not merely averages, but emphasis will be placed on extremes and variations from the normal, so that one may gain an adequate idea of the weather conditions likely to be experienced by a residence in the city throughout the year: The mean annual temperature is 51.7°, the average having varied from 48.5° to 54.3°. The graphical representation of this climatic factor is shown in figure 2, curve C. The highest temperature ever recorded was 102° in July, 1889, and the lowest was -20° in January, 1883. In figure 2 are also shown Page 11
Fig. 3.-Daily march of temperature; A, average daily maximum temperature; B, dally mean tem perature; C, average daily minimum temperature.
1875 1876 1877 1878 1879 1880. 1881 1882 1883 1884 1855. 1886. 1897. 188 1889. 1890 1891 1892 1893 1894 1895 1896. 1897 1893 1899 190). 1991 1992. 1903 1944 1905 19.15. 1907 1908 1909 1910 1911 1912 1913. 1914.
43 39 41 41 40 8+ 36 41 48
49.9 57.6 67.0 75.4 74.6 64.4 | 52.2
Highest and lowest temperatures in bold-lace type.
TABLE 1.- Monthly and annual mean temperature-Continued.
In Table 1 is given the average temperature for each month and year since 1875, with the normals. January is, as a rule, the coldest month, with a mean of 29.4°, although the lowest monthly average is credited to February, 1903, when the temperature averaged 20°, which is 13.4° below the February normal and 9.4° below the January normal. The normal for February is 33.4°, or normally 4° warmer than January, but in 41 years the average for February was nine times below the January normal and seven times below the January average for the same years. December's normal is 31.9°, or only 2.5° above the January normal. Since 1875 there were 11 years when the December average was below the January normal, and 11 years when the December average was below the average for the succeeding January. It is thus seen that there is a greater chance for December to be colder than the succeeding January or its normal than there is for February to differ from January in the same way. The hottest month is July, whose normal temperature is 75.4°. The July mean temperature varied from 71.9° in 1897 to 80.2° in 1901—a range of 8.3o. August is, on the average, only 0.8° cooler than July, and since 1875 there were 14 years in which the average for August was greater than the July normal, but there were 17 years in which the August average exceeded the average for the previous July. No June average has ever equaled a succeeding July average or a July normal. The month with the greatest plus departure was January, 1909, when the average for that month was 38.2°, or 9.4° above normal. The highest temperature in that month was only 56°, which is 4o below the highest January temperature on record. February, 1903, was the coldest month on record, taken as a whole; its average was 20°, which represents the greatest monthly deficiency, 13.4°. The lowest that month was only -4°, which is go above the lowest February and 16° higher than the lowest Junuary temperature.
Figure 4 presents some interesting facts regarding temperature characteristic of the various months. The highest and lowest temperatures ever recorded in the several months of the year are shown by curves A and B. Curve o shows the extreme monthly range in temperature, while curve D shows the
FIG. 4.-Curve A, extreme highest temperature cach month, 1875–1914; B, extreme lowest tempora ture each month, 1875–1914; C, extreme range, 1875-1914; D, greatest monthly range; E, least monthly range; F, greatest dally range; G, mean daily range.
greatest in any single month for the whole period. Considering the period as a whole, the greatest ranges occurred in winter and the least in summer; but when daily ranges are considered then the greatest are in summer and the least in winter.
No adequate idea of the temperature changes in a place may be conceived unless a study is made of temperature changes of months differing widely in character. In figure 5 curves are shown that give the daily mean temperature for the coldest and warmest January on record, and like plats are given for
FIG. 6.—Showing the contrast between the warmest and coldest months uring the period 1875 1914, the upper line representing the warmest month and the lower the coldest month. The broken line shows the normal daily temperature. the succeeding months of the year. A careful consideration of these curves, together with those giving traces for selected characteristic days, will aid one to a true conception of the temperature conditions likely to be experienced in Salt Lake City. 68436VOL 11-17-14
The average date of the beginning of the growing season is March 15 and the end is November 5. The latest spring frost on record is June 18, 1895, and the earliest fall frost was in the same year, on September 22, there being only 96 days to the growing season. The average date of last killing frost in spring, however, is April 21, and the earliest in fall is October 19, making an average of about 182 days to the frostless season.
FIG. 6.-Thermoisopleths for Salt Lake City, Utah, for the period 1875–1914. (°F.; 105th meridian time.)
Figure 6 shows the thermoisopleths for the city, for the period 1875–1914, in Fahrenheit degrees. The time used was one hundred and fifth meridian. The temperatures for a normal day in any part of the yea are easily discerned from this figure. While this is a considerable aid in obtaining an idea of the variation in temperature throughout the days of the year, it is by no means sufficent. One must know how temperatures vary in abnormal or representa
Page 12
tive days as well. A study of the curves shown in figureso ba to be, together with those in figure 5, will give a good conception of the temperature conditions in Salt Lake City.
In figure 6a thermograph traces are shown for relatively cool and cloudy July days, while figure 6b shows traces for warm and comparatively clear July days. On nearly all clear summer days the thermograph pen lingers for three to five hours near the maximum temperature as exhibited in figure 6b. Figure be is a thermograph trace for an average January day; figure od is a cloudy winter day; while figure 6c shows traces for 2 relatively cold winter days. TABLE 2.
Jan. Feb. Mar. Apr. May. June July Aug. Sept. Oct. Nov. Dec. Page 13
In Table 2 are given values for greatest, least, and average daily variability. The greatest daily variability occur in April and May, and the least in August. The greatest mean daily variability for any month is 7.1° for May; the least ja 2° in July, August, and November.
F1Q. 7.—Showing annual amounts of precipitation for period, 1875–1914. There are, on the average, 89 rainy days in Salt Lake City. The normal annual precipitation is 16.24 inches. Table 6 gives the monthly and annual amounts for each year from 1875 to 1914, while figure 7 shows the yearly amounts, the dotted line in that figure being the normal, and figure 10 the normal monthly amounts.
Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Doc. do Qual.
1875. 1876. 1877. 1878. 1879. 1880. 1881 1882. 1883. 1884. 1885. 1886. 1887 1888. 1889, 1890. 1891. 1892. 1893. 1894. 1895. 1896. 1897 1898. 1899. 1900. 1901. 1902. 1903. 1904. 1905. 1906. 1907 1908. 1909 1910, 1911. 1912. 1913. 1914.
3.05 0.79 2. 81 1. 50 2.91 0.90 1. 01 0.25 1.22 1.365.81 2.0393.44 1. 23 1. 52 4.00 2.09 4. 30 09 83 .87 3. 27 .88 2. 93 1. 80 2. 14 21. 23 3. 49 80 .28 .90 1.07 3. 49 2. 41 1. 02 1. 11 2.54 2. 63 16. 35 2. 50 . 35 1.08 .818.15 1. 87 1. 39 63 71 67 .11 3. 28 19. 76 . 10 1. 34 .07 06 .01 .29 1.02 1. 62 .32 3.08 43 2.37 13. 11 1. 85 .01 20 .74 56 . 40 1. 24 1. 17 2. 14 .88 2.37 1. 90 10.4 2.55 28 21 1. 61 43 2. 19 1. 50 .42 1.12 3.81 1. 44 1. 24 16. 88 . 26 2. 24 1. 61 .37 2. 89 1. 47 .72 1.75 2.92 .54 .92 | 15. 43 10 62 .13 .71 2. 23 3. 69 2. 24 1.79 1.20 11. 24 2.89 1.78 .33 .27 73 1. 48 1. 50 1.91 .36 .50 2. 12 17. 52 64 3. 47 2.49 2. 67 58 90 1. 29 1. 91 1. 36 59 3.10 2.60 4.43 .92 19. 60 1.02 T. 59 1. 88 1. 981.79 2. 36 1. 41 1. 27 1889 1. 87 .37 1. 23 55 1. 22 .25 1.55 11. 68 2. 18 .99 .98 24 63 .51 80 . 73 2.00 2. 21 13. 69 1. 64 1. 52 2.97 .08 92 528.85 3.07 2.05 1.12 1.044.87 18. 46 .94 .02 79 T. 74 76 1. 44 T. 10 83 4.68 1. 49 . 72 1.08 47 46 1. 19 1. 61 68 1. 26 .90 2.19 15. 92 2. 21 1. 90 1. 63 1. 21 T. 82 05 1.64 .12 1. 58 72 2.35 14.08 2.68 2. 72 1. 68 04 1. 19 711.30 1. 31 1.02 1. 18 2. 87 17.35 83 1. 73 1. 67 1. 22 1. 38 .82 .87 2. 87 1. 32 85 1. 01 28 81 1. 28 15. 27 . 73 2. 29 99 42 .02 1. 26 .95 24 69 2.44 1. 99 .80 11.95 2. 53 3. 67 25 1. 51 1. 47 . 52 .70 3.15 8.81 .84 1& 12 2. 20 2.00 52 69 33 .58 . 48 .38 1. 91 1. 19 1. 71 1. 47 16. 74 1. 30 4. 19 1. 45 18 84 1. 35 . 15 2. 98 1. 57 1. 95 2. 93 16 09 1. 28 .81 2. 59 96 .42 1. 06 T. 1. 30 2. 85 1. 52 .83 17. 57 .61 2. 91 08 32 .72 1.44 95 1. 77 1. 99 1. 40 . 16 11. 53 2. 48 .87 1. 27 19 31 1. 22 66 .80 98 16 08 1. 17 1. 16 1. 22 3. 69 . 33 37 56 2. 11 05 .52 .82 1. 24 11. 41 1. 35 1. 11 3. 55 74 .14 . 43 84 .81 1. 45 2. 25 2. 21 3. 99 .51 2. 20 3. 08 .27 59 28 .65 .12 1.18 1. 22 .00 90 2. 62 1. 70 2. 74 23 62 58 1. 19 2.07 24 1. 96 73 83 2. 84 3. 08 3. 17 1. 49 23 2.28 1. 75 1. 49 3. 45 .39 2 10 1.06 2. 35 1. 46 2. 87 1. 49 . 19 1. 69 1. 16 1. 24 1. 79 .50 2.21 80 5.76 1.81 25 1.39 2.72 2.07 2. 70 1. 89 1. 91 2.85 . 48 20.86 1. 60 2.34 17 .70 99 1. 74 1. 55 1. 13 1. 00 1. 46 1. 58 1. 50 74 2.64 1. 94 99 2. 04 1.16 11.35 1. 65 1. 84 45 02 05 1. 63 74 1. 65 1. 33 1. 48 3.48 2. 34 1.14 1. 75 .00 1.51 .81 1. 67 2.97 2. 50 1. 70 1. 95 57 8.87 . 92 10. 13 .47 1. 31 8.08 1. 21 1.35 1. 24 2. 84 2 68 1. 20 .24 261 .37 1669 1.34 1. 47 2.07 2.08 2.01 87 49 .77 92 1. 61 1. 34 1.3718 Page 14
El Pluviómetro, colocado desde un principio en la parte más elevada de la torre, a unos dos metros sobre la azotea, completamente libre de toda influencia local, tiene un diámetro de m. 0.71. Forma parte del Anemogetógrafo Denza que registra automáticamente a la par que la dirección y la velocidad del viento, la intensidad y la duración de la lluvia. El agua, empero, siempre se ha medido directamente apenas cesada la lluvia o en la hora inmediata de observación reglamentaria, utilizando las indicaciones del anemogetógrafo para hacer con mayor exactitud su distribución interhoraria.
Para esta Memoria se prescindió por completo de trabajos y publicaciones anteriores, fundándola directamente sobre los registros originales. En cuanto a la lluvia, se consideró tanto o más útil que el conocimiento de los totales mensuales y anuales del agua calda, un estudio detallado de su distribución por cantidades absolutas en forma tal que resulte fácil el darse cuenta de cómo se invierte el copioso caudal pluviométrico anual; que intervalos separan las precipitaciones de cierta consideración; si el país ofrece o no épocas claramente definidas de pobreza o de excesos udométricos; si son o no frecuentes los períodos de días seguidos con lluvias de consideración o sin lluvia apreciable; cuáles son sus grandes coeficientes o rerords en distintas unidades de tiempo, siendo de sentir que la manera de ser llevadas las observaciones no permita hacerlo para las breves duraciones en grandes aguaceros. Por lo que atañe al granizo, nos ocupamos en primer término de su frecuencia anual y estacional. Nos pareció interesante fijar conclusiones numéricas al respecto para poder correlacionar este temible fenómeno con las fases vegetativas, dando una base menos incierta a los cálculos del seguro. En cuanto al tamaño, la tradición del Observatorio debidamente consultada y el espíritu que fluye de la redacción de los apuntes diarios, muestran a todas luces que si deben considerar como casos sin importancia por todos conceptos, (tamaño, duración, cantidad) los mencionados sin comentarios. El autor de estas notas quiso, sin embargo, controlar el hecho (sobre todo para los últimos quinquenios) asegurándose de si figuraban como importantes en los Registros del Observatorio algunas granizadas que habían revestido este carácter y de las que había tenido conocimiento de haberse producido en Villa Colón por fuentes ajenas al Observatorio. El resultado confirmó el criterio mencionado más arriba. Para fines prácticos y tendencias teóricas, se consideró: I. La circunstancia de presentarse o no el granizo acompañado de lluvia, por ser bien sabido y muy tenido en cuenta en las estadísticas del seguro, que los perjuicios del mismo disminuyen considerablemente cuando cae mezclado con precipitaciones abundantes. II. La de estar o no acompañado de manifestaciones eléctricas, entendiéndose con cierta amplitud de tiempo la simultaneidad de los dos fenómenos. III. La dirección del viento en el momento de la caída del granizo, para ponernos en condiciones de señalar a los interesados una orientación oportuna en ciertos cultivos (sobre todo en frutales y viñedos) para una defensa más eficaz contra los efectos del granizo. Los comentarios son breves: el objeto de la Memoria es más bien el de suministrar elementos de aplicación merecedores, en nuestro concepto, de toda confianza y útiles por el largo período que abarcan (31 años) y la uniformidad de procedimientos empleados en la observación, que el de entrar, sobre la base de Page 15
También estos excesos, provocando inundaciones, favoreciendo el desarrollo de enfermedades y plagas, impidiendo las siembras o malográndolas, perjudicaron notablemente a nuestras industrias ganadero-agrícolas. Después de haber examinado registros de observaciones correspondientes a la región del Plata, algunas pertenecientes a la primera mitad del siglo pasado, otras a la segunda mitad del mismo siglo, pero anteriores a las nuestras, hemos formado la convicción (dentro siempre de la relatividad de valores en extremo variables) de que los extremos indicados pueden considerarse como absolutos seculares para nuestro clima. II. Marcha mensual y estacional.- Una preponderancia udográfica bien definida y constante a favor de ciertos meses o estaciones del año no resulta del conjunto de observaciones consideradas. Como puede verse a continuación, los totales medios de las estaciones difieren tan poco entre sí, que pueden considerarse prácticamente iguales : M/m. Verano, total medio de lluvia.. 254. O Otoño, total medio de lluvia-- 250.1 Invierno, total medio de lluvia. 251.9 Primavera, total medio de lluvia. 234. 6 Examinando los totales medios mensuales, aparecen más favorecidos marzo y abril, meses que tienen en su haber algunas de las más intensas inundaciones registradas en la zona, como la correspondiente al año 1895 y la de 1900; pero no es menos cierto que a esos mismos meses corresponden también cantidades mínimas de sequía, como por ejemplo, la de marzo de 1887 (con mm. 8.0) id de 1906 (con 6.4 mm.) id de 1909 y 1911 (con mm. 14.1 y 11.0 respectivamente); el mes de abril de 1892 (con 25 mm. 4) id de 1909 (con 17 mm. 6) no mencionando sino las valores que más se destacan por bajos. III. Extremos medios y absolutos mensuales. Los totales medios mensuales de lluvia fluctúan entre mm. 106 (marzo) y 65.8 (junio). Los extremos mensuales absolutos los retiene el ya mencionado año 1895 con mm. 386.3 para el máximum (marzo) y agosto de 1886 sin lluvia ninguna. La saltuariedad en la distribución de la lluvia también queda demostrada por el hecho de que todos los meses del año (con excepción de diciembre), retuvieron una o más veces el máximum como retuvieron el mínimum, a excepción de abril, julio y noviembre. De cualquiera manera, por lo menos para Montevideo, no tiene fundamento en las cifras el criterio popular bastante generalizado en todo el país que ofrece el invierno como la estación del año lluviosa por excelencia. Ni lo es por su cantidad de precipitaciones, ni por la frecuencia de las mismas, como veremos en su lugar correspondiente. IV. Marcha diurna.-Sin posibilidad de entrar al estudio detallado del fenómeno bajo el punto de vista especial de su frecuencia diurna, podemos aceptar al respecto las conclusiones a que se llegó en una publicación de 1893 análoga a la presente: en todas las estaciones hay predominio de lluvia en la madrugada y la mañana, acentuándose este predominio en la primavera, probablemente por el mayor contraste entre la temperatura del día y el minimum de la madrugada. En el transcurso de los 31 años seis veces solamente figuran como máximos en las 24 horas, valores superiores a los 100 mm. y son los siguientes por orden de importancia: Page 16
VI, Intervalos de días sin lluvia.-El resultado de la investigación llevada a efecto desde el año 1884 hasta 1914 figura en los Cuadros XXXIV y XXXV, con los dos criterios adoptados para el caso: en el primer cuadro se considera como intervalo sin lluvia todo aquel que no ofrezca lluvias por lo menos de un millmetro. En el segundo, de m/m 5.1 por lo menos. Creemos que para el estudio de las sequías en su fase práctica, mejor responde el segundo criterio, no pudiendo considerarse eficientes para las explotaciones ganadero-agrícolas en nuestro país, por razones que se correlacionan con la configuración del terreno muy ondulado, la naturaleza del suelo, la indole y forma de los cultivos, cantidades inferiores a los cinco milímetros, sobre todo a raíz de períodos de cierta duración sin precipitaciones y durante los meses calurosos. Intervalos sin Uuvia de 5.1 m/m por lo meno8.-El Cuadro XXXV nos demuestra : (a) Que una sola vez (el año 1893) se registró un período de 65 días sin lluvias que alcanzara a los cinco milímetros. (0) Que en los 31 años suman apenas diez los períodos de cuarenta o más días seguidos sin que la lluvia alcanzare a esa cantidad, lo que da un período cada tres años en término medio. (c) Que de los 1393 días de lluvia superiores a los 5 m/m unos cuatro cientos siguieron a días de análoga intensidad. Dias. El 41 % fueron separados por intervalos entre. ly 5 El 26 % fueron separados por intervalos entre_. 6 y 10 El 15 % fueron separados por intervalos entre 11 y 15 El 8 % fueron separados por intervalos entre 16 y 20 El 5 % fueron separados por intervalos entre- 21 y 25 El 2 % fueron separados por intervalos entre... 26 y 30 El 1 % fueron separados por intervalos entre 31 y 35 El 1% fueron separados por intervalos entre_ 36 y 50 El 1% fueron separados por intervalos entre - (max.) 51 y 65 Intervalos sin lluvia de 1 m/m por lo menos.-Las conclusiones a que se llega con este criterio, que reduce notablemente los intervalos mayores, son las siguientes: (d) Una sola vez en el año (en 1895) se registró un período de 41 días sin lluvia que alcanzara el milímetro o sea de sequía que bien puede considerarse absoluta. (e) En los 31 años suman apenas 30 los períodos de días seguidos sin lluvia por lo menos de un milímetro, lo que equivale en término medio a un caso por або. (1) De los 1537 días con lluvia superior al milímetro: Una mitad próximamente sigue a días de igual intensidad. El 59% fueron separados por intervalos entre.. 1 y 5 El 26% fueron separados por intervalos entre.. в у 10 El 9% fueron separados por intervalos entre--- 11 y 15 El 4% fueron separados por intervalos entre--- 16 y 20 El 1% fueron separados por intervalos entre-- 21 y 25 El 1% fueron separados por intervalos entre-- 26 y 41
En resumen : Del conjunto de observaciones se desprende que en nuestro clima tienen un gran predominio las lluvias de mediana intensidad y que ellas están distribuídas a lo largo del año con moderada frecuencia sin preferencias de meses o estaciones; en razón (término medio) de una cada cuatro días si se consideran todos los días de lluvia medible; una, cada cinco a seis días para las de 1 o más; una cada 8 a 9 días si se excluyen las inferiores a cinco milímetros; en in, una cada 20 días para las superiores a ese número. Page 17
Estos vientos son los que mayores peligros ofrecen a la navegación, no solamente por su gran intensidad, sino también por una serie de fenómenos que los acompaña, como son las nieblas densas que dificultan absolutamente la percepción de los objetos. Las velocidades de estos vientos son tanto mayores cuanto más rápidamente se verifica el ascenso de la columna barométrica y esto se comprende fácilmente teniendo en cuenta el régimen a que ellos pertenecen. Las aguas, obedeciendo a su influencia dan lugar a una serie de fenómenos de erosión en las distintas zonas del estuario. Las mayores crecientes son motivadas por vientos de esta dirección, levantando en la costa oriental lo mismo que los pamperos, el mayor oleaje y produciendo, dada la poca profundidad del río, una socavación en su lecho. La entrada de la onda que se forma en la desembacadura del río se produce bruscamente, por cuya razón las diferencias de nivel aparecen registradas sin los movimentos vibratorios característicos de la costa oriental, La temperatura y la presión atmosférica se sienten influenciadas por estos vientos experimentando la primera, descensos bruscos y presentándose las curvas barográficas con movimientos oscilatarios continuos, motivados por las enormes masas de nubes que ellos arrastran, las cuales se resuelven a su paso en lluvias o garuas. La acción de estos temporales suele durar varios días, y las aguas se mantienen durante todo el período de su actuación con pocas oscilaciones alrededor de las altas mareas ordinarias. El oleaje es general, y dada la orientación de la costa argentina ese movimiento toma una dirección transversal en los canales de Martin Garcia. Los vientos comprendidos del W. al S. son los que se distinguen con el nombre de pamperos, los cuales, a pesar de dominar con velocidades considerables, no ofrecen, en general para la navegación tantos peligros como los que actúan dentro de segundo cuadrante. De las observaciones registradas en estos últimos años, resulta que los grandes temporales del tercer cuadrante, han tenido en todos los casos la dirección W. 1 S. W., con momentos de 180 a 200 kilometros horarios, produciendo un oleaje continuo, con una altura media de metros 1.90 dentro de la bahía y dos diez a dos cuarenta al sur, en las proximidades del templo Inglés. Los pamperos pueden ser locales y generales. Los primeros son de poca duración y se producen con cielo despejado; los segundos tienen su origen en la cordillera de los Andes y suelen duras varios días, acompañados de lluvias y gardas generales. A estos vientos los antecede, pocos momentos antes de producirse, una serie de fenómenos fáciles de apreciar, presentándose como los más importantes el descenso continuo de la columna barométrica y la acción persistente de los vientos del N. y N. W., fuertes. Cuando se verifican las rotaciones del tercer cuadrante, se producen cambios totales simultáneos en las condiciones generales reinantes. El barómetro sube rápidamente, afectando las curvas barográficas la forma de un cono invertido, y la temperatura experimenta oscilaciones de 10 y 12 grados (centígrado). Estos vientos dan lugar a crecientes acompañadas de mucho oleaje, el cual se calma durante los períodos de lluvias garúas que siempre acompañan a estos temporales. Pocos momentos antes de actuar estos vientos, se nota que las velocidades de los N. disminuyen sensiblemente, hasta que se produce un intervalo de calma, en tanto que aparecen relámpagos lineales en el horizonte del tercer cuadrante. The CHAIRMAN. The next paper on the program is on the “Economic aspects of climatology," by Edward L. Wells, of the United States Weather Bureau, Boise, Idaho. Page 18
(6) Williams, Henry E. Protection of Food Products from Injurious Temperatures. U. S. Department of Agriculture, Farmers' Bulletin No. 125. Washington, 1901. (7) Hammon, W. H. Possibilities of the Weather Service on the Pacific Coast. Proceedings of the Convention of Weather Bureau Officials, U. S. Department of Agriculture, Weather Bureau, Bulletin No. 24. Washington, 1898. (8) Dalgado, Dr. D. G. The Climate of Portugal and Notes on Its Health Resorts. The Academy of Sciences. Lisbon, 1914. The CHAIRMAN. This very interesting paper is now open for discussion. We emphasize again the economic value of meteorological work and climatological data and meteorological information. It seems that meteorological services can best be organized only under some sort of government control and appropriation. It is sometimes a little difficult to get appropriations for things that do not seem to have an immediate practical value, and, I think, emphasis may well be laid upon the economic value of meteorological work in securing legislation in support of it. Mr. J. WARREN SMITH. The author of the paper spoke about two or three things that I would like to emphasize. One is the effect of the weather upon insect pests. In Ohio I have made some study of the effect of the weather upon the Hessian fly, the chinch bug, and the grubworm, the last two of which damage corn; and while I do not now remember the particular figures, the weather has a definite influence upon the damage done by all of those insects, and it can be determined a considerable time in advance. Mr. Wells has mentioned the importance of knowing the rainfall, and the amount of water available for power plants as well as for irrigation. I have in mind one large and very expensive power plant in Ohio that is practically worthless, because it does not have water enough to run the plant more than a short time in dry weather, and it has to stand idle for a month or six weeks in the dry season. The money spent in constructing it was practically thrown away. I wonder whether we have a suggestion in the matter of air-cooled refrigerating plants in Nansen's book, Through Siberia, published just a short time ago? I remember in one place he speaks of a mountain that was tunneled through in a region where the ground is not permanently frozen, but the mountain itself is frozen 250 feet deep, from the top down. Remember it is in a region where the soil is not permanently frozen, but they found this mountain itself was frozen 250 feet in depth. He explains it by the construction of the rocks in the mountain. He says that in the wintertime the cold air settles down through the interstices, and if there is any warming, it is confined to the surface, and that is repeated the next winter, and so on until there is that permanent freezing of the mountain because of the construction of the rocks. It may be possible to build a Page 19
The CHAIRMAN. If there is no further discussion, I will call on Prof. H. C. Frankenfield, of the United States Weather Bureau, Washington, D. C., who will read his paper on “ Sleet and ice storms in the United States."
SLEET AND ICE STORMS IN THE UNITED STATES.
By H. C. FRANKENFIELD, Professor of Meteorology, United States Weather Bureau, Washington, D. C.
The term "sleet" has been variously defined, and some of the definitions are manifestly inconsistent. The definition adopted by the Weather Bureau of the United States appears to be rational and consistent, and is as follows: Sleet is precipitation that occurs in the form of frozen, or partly frozen, rain, and is formed by rain falling from a relatively warm-air stratum into and through another air stratum that is sufficiently cold to freeze some or all of the raindrops. Mixtures of snow and rain are distinctly not sleet; neither are mixtures of hail and rain, as some of the foreign definitions permit. Another modification of sleet, but not actually true sleet, is more correctly known as “glazed frost," the German "glatteis,” or smooth ice. This is rain that actually falls to the surface as rain, but freezes as soon as it touches the surface. This formation is also considered as sleet in the Weather Bureau designation. It is most manifest on telegraph and telephone wires, trees, etc., and is the form that causes the greatest damage. The true sleet, falling as mingled ice and rain, does not cling, and does not often cause much damage. Both forms, however, are preceded by the same general meteorological conditions. The etymology of the term "sleet” is uncertain and none of the earlier available equivalents conveys any impression of its actual physical composition. Some of these equivalents are the middle high German “slöze,” the German "schlosse," and the Norwegian “sletta,” the latter meaning "to slap," and having reference, probably, to the beating or driving of the sleet under the influence of strong winds. Sleet and hail are distinct, both formatively and structurally; hail being formed by a violent uprush of warm air into a much colder air mass, occurs almost uniformly during summer thunderstorms; sleet pellets are not usually symmetrical in form, while hailstones are frequently so, being composed of a central nucleus of snow surrounded by concentric spheres of water and snow in alternate layers. However, for practical purposes It is not a serious error to define winter hail as sleet. The true sleet usually consists of considerable water in addition to the ice pellets, the pellets being of irregular formation ; but at times it consists entirely of round, dry pellets, about the size of duck shot, which either remain dry and loose on the surface for a considerable time, or, if the surface is slightly warmer, unite into larger and very irregular masses of ice. This has been termed "ice rain." The dry sleet is probably due to the unusually low temperature of the lower air stratum. A sleet storm of this character occurred at Davenport, Iowa, on March 5, 1900. The ice pellets remained perfectly dry and were blown about by the strong winds to such an extent that drifts, 4 or 5 inches in depth, were noticed in places. Page 20
In connection with storms in the United States I should like to give a very brief summary of some of the storms at Blue Hill Observatory. Out of 178 storms studied at that observatory between 1888 and 1914, 48 came in January, 46 in February, 40 in March, 27 in December, 10 in November, and 7 in April. The extreme dates were November 8 to 10, 1894, and April 30, 1909. The temperature during one storm ranged as low as 13° C., below zero, or 9° F. above zero. That was the extreme limit for rain falling in any ice storm. The conditions accompanying ice storms can be classified in three ways, commonly: First, when warm air is arriving from the south, rising over cold air below, formed in an anticyclone. This condition happens when a low pressure area from the west-southwest follows rapidly an intense anticyclone. The second condition occurs when you have a northeast wind below a south wind. On one occasion at Blue Hill there was a south wind blowing for several hours, and from the north a low fog was seen to come in off Boston Bay. This fog rose in the air, and then the rain which started to fall immediately began to freeze. The temperature fell from 40 to below freezing as soon as the northeast wind with its fog overtopped the hill. The third condition is where cold air pushes in from the northwest underneath a rain cloud. This happens most frequently when an anticyclone follows immediately after a cyclone. That is, the cold air rises before it stops raining from the clouds above. In 178 storms these three types occurred, sometimes all in one storm. The occurrence of the northeast type was 116 times, of the south type 67 times, and of the northwest type 59 times. I want to mention that the weather map shows that yesterday there was a slight ice storm at New York. There was a cyclone south of the anticyclone. The northeast type occurs most frequently when there is a cyclone crowded on the north by an anticyclone. That condition was true yesterday. Mr. BLAIR. I should like to speak on the same point that was brought out by Mr. Arctowski. I have a photograph of a formation that took place on a branch in about 14 or 15 hours. During this time the photograph shows that there was a succession in the formation of ice and frost. There were times when I suppose the fog particles were large, almost like very fine rain. At any rate there was a succession of dryness and wetness in the fog, which seemed to account for the peculiar formation. Another point of which I want to speak in connection with the paper relates to its economic aspect, which has been considered. We have observed these storms at Mount Weather, especially in their effect on fruit and forest trees. The damage done the trees is of two sorts. If the wind is very high after the storm ceases, the small twigs are broken off. If there is very little wind after an ice storm and especially if there is bright sunshine, we find the large branches broken. The wind whips off the small twigs, because of the weight of the ice, but when the wind is moderate after the storm, the ice remains on the trees and the difference in the expansion of the heavy ice coating, and the expansion of the branches owing to temperature change, results in the breaking of very large branches. I have seen branches 6 or 8 inches in diameter broken off from a tree in this way. The weight of the ice was not anything like sufficient to produce this result, and I assume, therefore, that it must have been the difference in the expansion of the ice and the wood. I think the coefficient of expansion of the ice is something like 10 times that of the branch. Page 21
The third great fire, which is known as the Columbia fire, occurred on the west side of the Cascade Mountains in the neighborhood of Portland, Oreg. This fire had been burning for some time, and it was under more or less control until September 8, 1902, when the winds so increased that the fire fighters could not prevent its onward progress. There were 18 lives lost in the Columbia fire, and property amounting to $12,767,100 was destroyed. The maximum wind velocity at Portland, Oreg., 30 miles from the fire, was 24 miles from the northeast on the day the fire got beyond control. Figure 3 shows the meteorological conditions prevailing on the morning of September 8, 1902. There was no well-defined cyclone near or approaching the region where the fires prevailed, but instead that locality was under the influence of a large anticyclone which was central over the State of Washington. The principal cyclone within the field of observation on that day, but which is not shown in the figure, was trough-shaped, and it extended from the Texas Panhandle northeastward to Lake Superior, with the greatest activity in the latter region. The gradients causing the winds that affected this forest fire sloped toward the so-called permanent summer low-pressure area overlying the interior of California. In predicting winds under the conditions prevailing at that time, the forecaster would receive his first intimation of their possibility through the presence of an approaching anticyclone, rather than a cyclone, as was the case in the two preceding illustrations. Furthermore, as anticyclones are usually associated with gentle winds (5), the prediction of high winds or even a fresh breeze under these conditions presents difficulties requiring the greatest care to prevent the prediction from being a failure. Whether the winds in this particular instance were predicted is not known by the writer, but if they were it is doubtful if the forecast was of benefit to the fire fighters, as they were not much better organized at that time than in the previous cases that have been cited. The fourth and last great fire to be illustrated occurred in northern Idaho. It burned over about 2,000,000 acres of woodland and killed 85 persons. This fire first became alarming on July 9, 1910, when a hot wind from the southwest began to blow, which quickly caused the fire to spread beyond the trenches, and it continued to burn furiously until the supply of fuel gave out on the next day. Figure 4 shows the weather conditions prevailing the morning of the day when the winds began to blow. A cyclone was central over the Canadian Northwest, and the front of an anticyclone was just making its appearance along the northern California coast. A forecast could have been made from the data on this map for a moderate southwest breeze during that afternoon, but the weather map issued on the morning of the preceding day did not contain sufficient information upon which to base a prediction of anything more than light winds, while the maximum wind velocity at Spokane, only 55 miles distant, was 23 miles from the southwest on the day in question. From the foregoing illustrations it can readily be seen that the dangerous conditions in every case were due to a small increase in the velocity of the wind, which could have been predicted a day ahead for the Michigan and Hinckley fires and probably about six hours ahead for the others. The winds causing the rapid spreading of three of the fires were those associated with cyclones, while in the remaining case they were those associated with anticyclones. The latter type is of most frequent occurrence as well as the most dangerous in Oregon, Washington, and California, because the winds generated by this type are always very dry and warm. Page 22
As an illustration of what could be done along these lines, an extract from an unpublished report (6) by Forest Supervisor W. L. Merritt and Mr. W. J. Sproat from data obtained without instruments in the Deschutes forest and Deschutes division of the Paulina forests, follows:
1. The normal wind movement seems to be from an eastern direction in the morning and early forenoon, and from a western one in the afternoon. Severe winds almost invariably blow from some westerly direction, and not from the east as has sometimes been stated. General eastern winds apparently are not dangerous in this locality. 2. Generally the wind dies down at night and does not become severe until about 10 a. m. tlie next day. Every effort should be macle, therefore, to control fires before that hour of the morning. 3. It is thought the winds are not extremely dangerous until after the velocity exceeds about 15 miles an hour. When the rate is this amount or more it is extremely difficult to control fires that may be burning. 4. A study of the chart of general conditions in Oregon and a general knowledge of the topography and conditions throughout the eastern portion of the State seem to indicate that severe windy periods come after the high-lesert region has become excessively heated during the period of high temperatures, causing low-pressure areas and resulting in a strong wind movement toward the east. 5. Although no smoke records were kept last summer, it was our general observation that smoky conditions were coincident with severe windy periods, no doubt due to the fact that eastward air moi ements brought in smoke from the west slope of the Cascade divide. 6. It is probable there is some relation between lightning storms and the causes which precede severe windy periods. Since no records were kept of lightning storms last summer, however, this point can not be stated with certainty. Lightning records will be kept during the coming season. In another part of the report by Messrs. Merritt and Sproat, mention is made that, “although the wind records for that day did not show that the conditions were bad, the wind really blew very hard at the fire itself.” It is well known that forest fires cause strong convectional currents and that inflowing surface winds result therefrom of greater or less velocity (7). This interesting phenomenon should be thoroughly investigated, as next to nothing is now known regarding the area surrounding fires that is thus affected. Dry periods are not classified and published by the Weather Bureau, and, furthermore, there are at present only a few places in the forests where a record of the weather is kept; therefore, very little is known regarding actual periods of drought in the timbered regions west of the Rocky Mountains. That rainfall on the Pacific slope increases with altitude is well known, also that the forests in that section are nearly all located on the sides of mountains, consequently the rainfall in the valleys some distance away is a poor guide upon which to base an estimate of the amount that falls in the more elevated regions where the forests are situated. The establishment of weather stations on mountain slopes where there are forests is difficult of accomplishment, unless the observers are paid a salary sufficient to make the observation work their chief occupation, and to do this would so increase the cost as to make the service prohibitive. There are so few settlers in forested regions that it is seldom possible to obtain the services Page 23
(7) The Value of Weather Forecasts in the Problem of Protecting Forests from Fire. Monthly Weather Review, February, 1914. (8) The Spell of the Rockies, by Enos A. Mills (1911). (9) Forest Fires. Forest Service Bulletin 117. NOTE.—Credit is due Mr. Floyd D. Young for preparing the weather maps shown in figures 5 to 12, inclusive, most of which were drawn by him outside of office hours. For this service the writer desires to express his grateful appreciation. The CHAIRMAN. I think perhaps the members have not realized, because of the modest manner in which Mr. Beals has presented his subject, that he himself is one of the foremost workers in the application of forecasts to the prevention of forest fires. The work in a certain sense has originated in his district, at Portland, Oreg. The paper again illustrates the tremendous economic advantage of meteorological work in conservation. I hope the paper will be fully discussed. Mr. WELLS. Mr. Chairman, Mr. Beals mentioned the difficulty of getting accurate meteorological data in the forests, and referred to the fact that all the stations are in the valleys. I may mention in this connection that in northern Idaho, a part of the territory which Mr. Beals covers with these forecasts, there was established during the summer of 1915 a chain of lookout stations. These stations will be manned by representatives of the Forest Service during the summer, particularly during the period of fire hazard, and we have supplied a number of these stations with the cooperative observer's outfit-maximum and minimum thermometers, rain gauges, and other instruments of that sort. I believe that it would be best to install anemometers, and to keep a record of the velocity of the wind. That would mean that it would be necessary to send a trained meteorologist there occasionally to inspect the anemometers and see that the records were properly kept. I do not think the record would be satisfactory unless it were supervised in that way, but I feel that it would be well worth while to do just that thing. Mr. Henry. Mr. Chairman, it seems to me that Mr. Beals is attempting a very highly specialized kind of forecasting. The conditions that produce forest fires on the Pacific coast are not the conditions which are found in the East. The problem seems to be one that can best be solved by the forecaster himself. I do not believe that lookout stations will be of much assistance in the matter. It is clearly a meteorological problem, and whether or not these high winds will occur depends not so much on the local conditions as upon the conditions over a widely extended area. We must rather depend on telegraphic reports from widely separated points for the proper presentation of the pressure distribution which will cause these winds. Therefore, I think the problem can best be solved by reports upon the pressure distribution as shown by the synoptic weather chart. Page 24
Mr. Brown. Very possibly that is so. Mr. BAUER. I will send you a copy of that letter. Mr. Brown. The advantage of getting the arc as far south as possible is very great. That is why I suggested Argentina. Of course, the observations could be made at any time and the errors determined later. Mr. BAUER. Observations are being made of the northern boundary of Uruguay, and I believe you will get the accurate latitude from that. Mr. Frisby. Suppose these observations were all made with the best degree of accuracy, what relative weight would Prof. Brown give to the results of the observational and the gravitational methods? Mr. Brown. What I am doing here bears on an equation which really contains two unknowns. We assume practically that the gravitational determination is accurate to the hundredth of a second of arc. It is practically known to a hundredth of a second of arc as soon as the ellipticity is determined. So we can consider this as accurate, and if we have, say, 400 pairs of plates, we can get that, I think, within three or four hundredths of a second of arc. Mr. Frisby. Your idea is that they will practically agree. Mr. Brown. We shall have to use a value of ellipticity that will make them agree. Mr. Frisby. They will use the two methods and get a result from them ultimately. Mr. Brown. Yes. The Hayford and Bowie observations got a result of 297, and from two other methods I got 293.5, so I am wondering whether I am wrong, or whether there are different values of the ellipticity according to the different methods in use. Clark's geodetic method got 293.5. Something depends on moments of inertia and something on inequality of the surface. Mr. Bowie. From geodetic work the ellipticity is determined at 297, and from gravity alone and a comparatively few stations, but for those in the United States it is 298.3 or 298.4. Mr. Brown. That is practically Helmert's value. Mr. BOWIE. Helmert has recently got values that agree a little more closely. Mr. Brown. The moon, in two different directions, gives 293.5. I am not going to admit that the moon is altogether wrong until the question is settled where this large difference of three and onehalf units at least comes from. The CHAIRMAN. I might add that Prof. Brown has put his finger, so to speak, on the important point-namely, the determination of the station error. We must know the deflection of the plumb line accurately, which will require a primary triangulation over a considerable area, and I think we may confidently expect that our colleagues in Argentina will extend such a scheme of triangulation in the near future; but, of course, the near future for astronomers may mean 50 or 100 years. Page 25
Now that the primary triangulation has been sufficiently extended to permit the adoption of a standard or final datum (called the North American datum), nearly all of the determinations of astronomic azimuth, latitude, and longitude are made for the purpose of ascertaining the deflection of the vertical in the meridian and the prime vertical at triangulation stations. At intervals of from four to six quadrilaterals in an arc of triangulation, the astronomic azimuth and longitude are determined in order to obtain the astronomic azimuth freed from the effect of station error. This azimuth is used in adJusting the triangulation. Azimuth. The observations for azimuth are made upon polaris by the party making the observations for horizontal and vertical angles in the triangulation. The distance between azimuth stations varies from 60 to 100 kilometers, de pending upon the lengths of the lines and the weather conditions. During a long period of cloudy weather which does not retard the triangulation observations, the azimuth stations are more widely spaced in order not to delay the triangulation materially. It is more economical to establish additional azimuth stations at another time under such circumstances. For the purpose of the determination of the figure of the earth and the distribution of densities in the earth's crust it would be advantageous to have the astronomic azimuth determined at each primary triangulation station, but at present the added cost would not be justified. There are now in the United States 300 astronomic azimuth stations which can be used for determining the deflection of the vertical in the prime vertical. Cost of azimuth determination8.--The determination of an astronomic azimuth does not retard the triangulation observing party more than one day at a station, on an average, and consequently the cost of an azimuth station is about $50. This is the average cost of a working day for the party. When the azimuth is determined separately the cost of a station will be about $148, the same as for a latitude station. Latitude.-In recent years the astronomic latitudes on any one or more arcs have been determined by a party specially equipped for the purpose. The observations are made with the zenith telescope, by the Talcott method. In general, 16 pairs of stars are used, with each pair observed only once. The accuracy required is a probable error not greater than 0.10 second of arc, and all of the observations may be made on a single night. The party consists of four persons, including the observer. They live in tents and move from station to station in an automobile truck. The last 63 stations determined were in very rough country and the truck proved to be a very efficient means of transportation. The truck was driven as close to the station as practicable and then the instruments were carried to the station by pack animals or by the members of the party. Before the truck was used (for the first time in 1913) the latitude party traveled from station to station by railroad and hired teams. The astronomic latitude stations are spaced along an arc at about the same distances as are the azimuth stations; that is, from 60 to 100 kilometers. For scientific purposes these stations should be placed close together, but it is not expedient to do so now. In the United States there are 470 latitude stations, which can be used for determining the deflection of the vertical in the meridian. Cost of astronomic latitude determinations. There are no cost data available for the astronomic latitudes in the United States for those stations established previous to 1905. The following table gives the costs for the several seasons' work since that date. The means of transportation during the last two seasons was an automobile truck. It is seen that the cost for a station during those two Leasons was, on an average, less than for the previous work. Page 26
The preceding table shows that, during the past nine years, 617 stations have been selected on 7,111 kilometers of arc and that the mean cost per kilometer of progress has been $2.28. The frequency of base lines on an arc depends upon the strength of the - quadrilaterals and the average length of line. The distances apart vary from 800 to 600 kilometers. With the ease with which a base may now be measured there is a tendency to shorten the distances between bases. Preparation of stations. The preparation of the stations is made, in most cases, by a separate party, as in the selection of stations. At each station there is placed a metal disk properly inscribed. This is set into a block of concrete, a large bowlder, or the solid rock, depending upon the local conditions of the earth's surface at the station. When the ground is flat a double structure is erected at each station, on which rest the instrument, heliotrope, and lamp. These structures are built only as high as is necessary to make the stations intervisible. When the country is hilly or mountainous only low stands are erected to support the several pieces of apparatus. It is difficult to estimate the average cost of the preparation of the stations, for it varies with the heights of the signals. A very close estimate for the cost of erecting the high structures is $9 per vertical meter. This cost includes all expenses incident to the work, as well as salaries and traveling expenses. A structure 20 meters in elevation will cost about $180. The cost of preparing stations is included in the cost of the observing, which is given below.. Observation of horizontal and vertical angles.—The accuracy required in the horizontal angles of primary triangulation is that represented by an average closing error of about 1 second of arc and a maximum error for a single triangle not greater than 3 seconds. Usually this accuracy can be obtained by making 32 observations on each station with a 12-inch (30.5-centimeter) direction theodolite. Not more than 32 observations are made unless a triangle closes with an error greater than 3 seconds. It is frequently the case that all the horizontal angles are measured in a single day. An analysis of the work on the Texas-California arc was made and it was found that the accuracy of the work done at stations in a single day was equal to that at the stations where two or more days were required to complete the observations. Trigonometric leveling is carried on at the same time as the horizontal observations, the vertical angles being measured with small vertical circles, usually not more than 7 inches (17.8 centimeters) in diameter. The vertical measures are usually nude in the afternoon between the hours of 1 and 4. The observing party consists of four persons, one being the observer who is in charge of the work. They live in tents and move from place to place in wagons, drawn by horses, or in automobile trucks. The latter were used with great success during the season of 1915 on the Idaho-Oregon arc. It is probable that the truck will be used almost exclusively in future work. The observations for horizontal angles are made upon heliotropes during the late afternoon and upon signal lamps, burning acetylene gas, at night. Experiments are now being made to develop an electric lamp which will be of much greater power. Usually from six to eight men are employed throughout the season to operate the heliotropes and lamps. Their movements are directed by the observer. Each member of the party learns the alphabet of the telegraphic code and messages are flashed between the observing party and the light keepers. The latter move by hired teams and by railroads. |
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