march eastward and reach Newfoundland in about one hundred and twenty hours. For example, a storm passed from Sitka to St. Johns between January 12 and 17. This storm did not originate in the Northwest Territory, but clearly came in from the Pacific. Where it did originate we do not know, but it is an error to locate its origin in any of the Northwest territories. And this is probably true of most storms which are said to originate over Athabasca or Saskatchewan. The truth is that storms first come into notice in these localities, but originate elsewhere. The storms of the Pacific coast present a characteristic that is worthy of special study, viz, an apparent oscillation from the ocean to the land, and vice versa; that is to say, the low approaches the coast and partially disappears, reappearing within a period of twelve to thirty-six hours, and continuing this action until the storm finally disappears. During the past two years I have been engaged, during my leisure time, in preparing weather charts of the Pacific Ocean. Some remarkable information has been obtained from these charts. The storms that approach the Pacific coast from the ocean frequently recurve several times after touching the coast, the number of oscillations being greater the farther south the storm approaches the coast. The fact that a storm moves southward, ricochetting along the Pacific coast, and probably dying away as it progresses, harmonizes with the general theory of the movement of vortices. If the general distribution of pressure at sea level, and especially at 16,000 feet, is such as to give the storm center a general movement southward or southeastward along the Pacific coast, then the influences of the high mountain land in the interior of California and the plateau lands of Idaho, Nevada, Oregon, Utah, and Arizona are like those of a barrier against which a small atmospheric vortex may strike, only to be reflected several times in succession. A further special influence of these high lands is to furnish descending dry air whose mixture with the moist air of the whirlwind rapidly diminishes the quantity of condensation and the sustaining power of the whole mechanism. The inverse conditions prevail on the east slope of the Rocky Mountains, where, therefore, a whirl once started is apt to increase in all characteristic phenomena. Possibly this process is illustrated by the low area of October 29, 1896, in regard to which Professor McAdie writes: "On Monday, October 26, 1896, a. m., a low, 29.70, with southeast winds, appeared on the Oregon coast. Taking a most unusual course, this storm passed southward and on the morning of the 27th was over central California (San Francisco, 29.56, southeast wind, 1.10 inches rainfall). By 10 o'clock of the same day the storm was moving down the San Joaquin Valley, and heavy rain was falling over southern California. On the morning of the 28th the pressure was 29.78 at El Paso, with rain, and the storm was out of our limits of observation, but just coming into prominence elsewhere." PREVAILING AIR DRIFT AND OCEAN EFFECT. The prevailing easterly drift of the atmosphere in temperate latitudes, causing the wellknown winds from the west, is one of the prime factors in modifying the climate of the coast of California, This coast line, stretching for 10 degrees of latitude, is subjected to a steady indraft of air from the west. In this movement, together with the fact that to the west is the great Pacific Ocean, lies the secret of the difference in temperatures between the Atlantic and the Pacific coasts at places of like latitude. For some years there has been an impression that the milder climate of the Pacific coast was due to a warming influence of the Kuro Siwo, or Japan current. No reliable data exist to support such a belief, and it is quite unlikely that the Japan current plays any important part in modifying the climate of the Pacific coast. The active factors are, as said above, the prevailing easterly drift of the atmosphere and the proximity of the mass of water, a great natural conservator of heat. Further on, the equability of the mean annual temperatures along the coast of California, a distance of nearly 1,000 miles, is discussed, and the area might be extended to include practically the whole of the Pacific coast. One of the most noticeable differences between the climate of the Atlantic and Pacific seaboards is found in the trend of the isotherms, those of the Atlantic coast corresponding more or less with the parallels of latitude, while on the Pacific coast the isotherms run more nearly like meridians. Too much emphasis can not be laid upon the effect of these two factors, the easterly drift of the air and the proximity of the ocean in modifying climate. It is probable that if one of these conditions could be reversed and the general movement of the air in these latitudes be from east to west, marked differences in climatic conditions would result, and the Pacific coast might then have a rigorous climate. TOPOGRAPHY. The State of California extends from latitude 32° 40′ north to 42° north with a mean length of something less than 800 miles. The average width of the State is about 200 miles, and it has an area of 155,980 square miles, or 99,827,200 acres. The coast line of the State corresponds in position to that portion of the Atlantic coast extending from Boston to Savannah. Very few rivers, however, empty into the ocean, and in both topography and hydrography there is but little resemblance between the Atlantic and Pacific seaboards. The mountain ranges and other marked physical features play an important rôle in determining local climates, a discussion of which in detail will be given further on. It will not be out of place at this point, though, to call attention to the fact that the highest and lowest lands in the United States, excluding Alaska, are in California. Mount Whitney has an elevation of 4,427 meters (14,522 feet "); Mount Shasta, 4,383 meters (14,380 feet); and by referring to the table of elevations it will be seen that we know of at least 43 well-defined mountain peaks with elevations exceeding 3,048 meters (10,000 feet). On the other hand, at Salton and Volcano the depression is 80 meters (263 feet) below sea level. Death Valley, the bed of an old lake about 75 miles long and 6 miles wide, lies in southeastern California, just north of the great Mohave Desert. A few illustrations showing the diversity of climatic conditions may be of interest. In the Colorado Desert, in the southern portion of the State, shade temperatures as high as 54° C. (130° F.) have been recorded. Mean monthly temperatures not much below 38° C. (100° F.) frequently occur at Volcano, Salton, Indio, Mammoth Tank, and other places in the great arid regions of southern California, and particularly in the Valley of the Colorado. In the Sierra, just north of Lake Tahoe, temperatures as low as -34° C. (-30° F.) have occurred. During the winter of 1898 a minimum thermometer exposed on one of the high Sierra peaks, Mount Lyell, recorded -27° C. (-17° F.). During the same period the temperature at Bodie reached a minimum of -34° C. (-30° F.). The mean annual rainfalls, as might be expected, vary from 1 inch to 75 inches. At Mammoth Tank for twenty-three years the mean annual rainfall amounts to 1.81 inches, but here and at other stations there have been years when the rainfall did not exceed a trace. At Upper Mattole the average annual rainfall is 81 inches, and in indvidual years rainfalls approximating 100 inches have occurred. The following are some single year rainfalls: Laporte 120 inches, 1896; 101 inches, 1898. Bowman's Dam 119 inches, 1884; 110 inches, 1896. Delta 111 inches, 1889; 100 inches, 1896. Upper Mattole 102 inches, 1896; 101 inches, 1889. Edmonton 102 inches, 1896. Snowfall is confined in general to the central and northern portions of the State and to the mountains of the south. At Summit an annual snowfall of 697 inches has been reported. The coast line of nearly 1,000 miles shows a difference of but 10 F. in the mean annual temperatures of its northern and southern limits. At Eureka the temperature is 11° C. (51° F.): at San Francisco, 13° C. (56° F.), and at San Diego 16 C. (61° F.). That the coast climates are very equable is shown by the following mean monthly departures. At Eureka the mean January temperature is 46°, or a departure of 5° from the annual mean; at San Francisco the mean January temperature is 50°, or a departure of 6° from the annual mean, and at San Diego the mean January temperature is 54°, or a departure of 7 from the annual mean. Similarly for the month of July the temperature at Eureka is 56°, or 5° above the annual; at San Francisco, 59, or 3 above the annual, and at San Diego 68°, or 7° above the annual. The highest mean annual temperature found in the Colorado Desert is about 78°, and the lowest mean annual temperature for stations in the Sierra (Summit, for example) is 42°, or a total annual range of 36°. The absolute range as stated above is from 130° F. (54° C.) to -30° F. (-35° C.); 160° F. (89 C.) a Authority, Langley. Authority, U. S. Geological Survey. Authority, The Sierra Club, of San Francisco. The various elements of sunshine, humidity, wind velocity, and direction vary in different parts of the State to almost as great a degree as rainfall and temperature. Unfortunately continuous and systematic records of these elements are not available for most portions of the State. The general movement of the air over the State is from the west and north, with strong southeasterly indrafts during the months of November, December, January, and February whenever marked cyclonic disturbances approach the State from the northwest. The general movement of the air in California is decidedly modified and certainly in the lowermost strata almost entirely controlled by the topography. Particularly interesting are the accentuated movéments in the great valleys, as shown in the well-known "northers" of May and June. The prevailing westerly winds, wherever allowed access to the interior through gaps in the Coast Range, are greatly intensified and exhibit in both frequency and duration a well-marked relation to the temperatures prevailing in the interior. One of the most trying climatic conditions prevailing in California is the so-called "norther” or hot north wind which, blowing in the great valleys, is both injurious to ripening crops and irritating to man and beast. May, June, and July are the months of greatest frequency. The condition is as a rule associated with the presence of an area of high pressure over the North Pacific Ocean and a deepening of the usual summer "low" over southeastern California and the Valley of the Colorado. Temperatures of 43° C. (110° F.) or more occur under these conditions. As these brisk northerly winds are very dry and dust laden, ripe fruit and wheat are seriously injured, while human beings and stock suffer greatly because of the irritating effects of the "norther." In southern California a somewhat similar condition is known as the "Santa Ana." In all of these cases the air has been dynamically heated and dried, either by descensional movement, as when flowing down the mountains or by horizontal movement over superheated plains and deserts. In the tabulated data which appears further on it will be noticed that the general conditions of temperature and rainfall are greatly modified by the local topography. In California, perhaps more so than in any other part of the habitable earth, a great diversity of climate exists. Within comparatively short distances one may pass from a climate requiring the lightest of summer garments to one requiring overcoats and heavy wraps. A short study of a relief map of California will throw much light on the cause of the great diversity of climate. The subject is discussed in detail in the chapter upon the "Climate of San Francisco," where a marked modification of the normal conditions is undoubtedly affected by the peculiar topography of the locality. TABLE OF ELEVATIONS EXCEEDING 1,000 METERS (3,281 FEET) IN CALIFORNIA. Many of the elevations have been supplied by Profs. George Davidson and J. N. Le Conte. For peaks in the High Sierra not included here see supplementary tables. a This table was compiled for the Sierra Club by Mark B. Kerr, C. E. and R. H. Chapman, of the U. S. Geological Survey. |