USA > California > History of California, Volume V > Part 6
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A little careful work with a fine pointed instrument in the now cheesey matrix, a bath in gasolene, drying in sawdust, and a final polishing with soft cloth turns these specimens into dark stained, lustrous bronze, bearing even the most delicate imprint of their former clothing of muscle and ligament. The studious eye of science, reading these traces, clothes the whole in living semblance and the animals of Rancho La Brea are called to resurrection.
In this horizon, again, the relationships of the birds point to a withdrawal of their immediate descendants toward the southward. The eagles, the storks, the vultures, the caracara, the peacock have left their nearest living relatives in Mexico, Central America, and South America.
According to the evidences of paleontology the ground sloths without question, had their origin in South America and wandered thence northward into the United States; the bison and elephants came south- ward from Alaska where some land connection had let down the bars between this and the Eurasian continent;
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HISTORY OF CALIFORNIA
Horses, camels, and saber tooths probably grew up with the country; lions and bears came with the ele- phants from the north, while the peccaries developed with us, then went south to Mexico and later diffused back into the Sonoran of Texas. These records of ancient animal migrations, coupled with the present phenomena of horizontal and vertical distribution show an effect as of successive wave upon wave of biological impetus moving now north, now south, swirling and eddying across the changing face of the country, strand- ing some species, washing away others, scouring a pathway for still others, till our flash light of this great sea of forces, the instantaneous view we call the present, reveals the fauna of California, clothing her in a rich and varied robe of many colors.
PARTIAL LIST OF AUTHORS CONSULTED
Grinnell, J. Various papers in the University of California Publications, Department Zoology and in Condor magazine. Merriam, C. H. The Geographic Distribution of Life in North America, Smithsonian Report, 1891.
Merriam, J. C. Various papers in the University of California Publications and in Science.
Miller, L. H. Various papers in the University of California Publications and in Condor magazine.
Swarth, H. S. Various papers in the University of California Publications and in Condor magazine.
Willett, G. Birds of the Pacific Coast of Southern California, Cooper Ornithological Club, Pacific Coast Avifauna No. 7.
Loys Miller
THE CLIMATE OF CALIFORNIA
T HE climate of a country is determined primarily by geographical latitude, by prox- imity to large water areas, by the topography, by prevailing drift of the lower or surface air and by storm frequency. In California there are five well marked factors operating to control climatic conditions. Of these perhaps the most important is the prevailing drift of the surface air from west to east, common to temperate latitudes, but marked in this section of the American continent. In this great aerial stream are the lesser currents induced by the eddies and counter-eddies familiarly known as "lows" and "highs." It has been found that these disturbances for the most part drift east along a line north of Cali- fornia and this is the chief reason why the weather in general is less changeable than in regions nearer the storm tracks or paths of greatest storm frequency. Again, the proximity of the Pacific Ocean, a great natural conservator of heat, serves to prevent marked temperature changes. Ocean currents also exert a certain influence, their effect in the main being to cool the surface air and facilitate cloudy condensation, thus promoting the formation of fog. Finally the diversified topography of the State determines what may be called local climates. The prevailing flow of air is from the west to the east, that is from the sea to the land. During the day hours as a rule this flow is increased; but during the night hours, the wind veloci- ties are diminished. In the general drift we find the cause of the strong westerly winds so characteristic of the California coast. Charts of wind direction formerly issued by the Weather Bureau but now by
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HISTORY OF CALIFORNIA
the Hydrographic Office show with much detail the fre- quency and intensity of the wind for all parts of the coast. From the 55th parallel to the 30th the winds are chiefly northwest. In summer between latitudes 35°N and 40°N winds are distributed as follows: west to northwest, 75 per cent; north to northeast, 4 per cent; east to southeast, 3 per cent; south to southwest, 3 per cent; and calms, 15 per cent. In winter the winds are southeasterly, and southerly gales are frequent. Nevertheless, northwest winds are not infrequent as is shown by the following: west to northwest, 30 per cent; north to northeast, 18 per cent; east to southeast, 17 per cent; south to southwest, 22 per cent; and calms, 13 per cent.
It is because of this general motion of the air from west to east that the climate of west coasts is less severe than the climate of east coasts. If the circulation of the surface air were reversed, the Atlantic coast and the middle portion of the country would have less varia- tion of temperature and the climate would be in many respects milder than that which now exists. On the other hand, the climate of the Pacific coast, and espe- cially of California west of the Sierra Nevada, would lose much of its present equability. The winters would be rigorous and the summers very warm.
The mean annual temperature of the Pacific near the California coast is 13ºC, 55°F. The prevailing winds therefore blow over a surface that is warmer in winter and cooler in summer than a land surface would be. The temperature amplitude of all the coast stations is consequently small compared with that of the interior. During the summer months the mean
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THE CLIMATE OF CALIFORNIA
temperature of the water is about 15℃, 60ºF. The diurnal change in the temperature of the water is small. During the winter the mean temperature of the water is about 10℃, or 50°F. Interesting comparisons of water-surface temperatures, air temperatures and cur- rents may be found in the Ocean Charts referred to above. One point however should be noted in con- nection with air temperature at sea, and that is that observations are made close to the water surface and do not represent the air conditions at a height of several hundred feet.
In the diversified topography of the state, we have another important factor in determining local climates. The state has a mean length of nearly eight hundred miles and an average width of two hundred miles. Its area is 155,980 square miles, or a little less than a hundred million acres. The coast line corresponds in position with that portion of the Atlantic coast extend- ing from Boston to Savannah. There are very few rivers, and in both orography and hydrography there is little resemblance to the Atlantic seaboard. The coast line has a mean annual temperature ranging from 10℃, 50°F to 15℃, 60ºF, while on the Atlantic coast the temperature ranges from 8℃, 47ºF to 20℃, 68ºF. In July the isotherms run almost north and south on the Pacific coast, while on the Atlantic coast they conform to the parallels of latitude. In the winter the difference between the mean temperature of the interior of California and the coast amounts only to about 3℃, 5°F, but in the summer the difference is marked, amounting in general to 11ºC, 20°F.
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HISTORY OF CALIFORNIA
Orography plays an important part in controlling the movement of the surface air. The prevailing westerly winds, wherever allowed access to the interior through gaps in the Coast Range, modify and practi- cally control the temperature. On the other hand, when the movement of the surface air is from the north or northeast, there are marked föhn effects due to the passage of the air over the mountains and thence down into the valleys. One of the most trying climatic features of California is the so-called "norther" or hot wind, caused by dynamic compression of rapidly moving air. Northers occur in the great valley chiefly during May, June and July. Their occurrence is associated with the presence of high pressure over Oregon and Idaho and a deepening of the usual summer low over the valley of the Colorado. Under such conditions, afternoon temperatures rise to 43℃, IIOºF, or even higher.
In the southern portion of the state there are winds of similar formation known locally as Santa Anas.
In all these cases the air has been dynamically heated and dried in its passage from the Great Basin southwest or south over the Sierra Nevada and thence down the western or southern slopes. The velocity of the wind sometimes exceeds ten meters per second (twenty miles an hour), and as much dust is carried, the conditions created are generally disagreeable.
During December and January under certain pressure distributions there are well-marked föhn effects in the counties south of the Tehachapi. Afternoon tempera- tures will exceed 80°. Morning temperatures, however, are low, owing to intense radiation.
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THE CLIMATE OF CALIFORNIA
We thus have the same pressure distribution resulting in cool nights and warm afternoons.
STATE DIVISIONS
For convenience in discussing the data, the state has been divided into five sections, bearing some relation to the principal watersheds. These divisions are:
Northwestern California
Northeastern California
Central California
California south of the Tehachapi
California east of the Sierra Nevada
NORTHWESTERN CALIFORNIA
This includes the coast counties north of the bay of San Francisco, also the Coast Range counties west of the Sacramento watershed. Beginning with Del Norte and the western half of Siskiyou counties, the district extends south including Humboldt, Trinity, Men- docino, Lake, Sonoma, Napa, and Marin counties. The four last named constitute a subdivision, known locally as the Bay counties. There are four small valleys in this subdivision, known as the Russian River, Sonoma, Napa, and Vaca Valleys.
The Coast Range runs north and south through the entire district and climatic conditions vary greatly within short distances, owing to the diversified topography.
The coast line is bold and rugged. There are many projecting headlands, the best known of which is Cape Mendocino, latitude 40°30'N. The well-known Point Reyes, latitude 38°II'N, longitude 122°51'W, is formed
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HISTORY OF CALIFORNIA
by a westward projection with a hook to the south, thus making an open roadstead, known as Drake's Bay. Francis Drake anchored here in June, 1579.
There are few harbors in the 290 nautical miles .* The following table gives the distance in nautical miles of the chief headlands:
San Francisco to Point Reyes 33 miles
Point Reyes to Point Arena 67 miles
Point Arena to Cape Mendocino 98 miles
Cape Mendocino to Eureka 23 miles
Cape Mendocino to Point St. George 78 miles
The Coast Range extends in a nearly north and south line the entire length of the district. The St. Helena Range is the best known of the several minor ranges. Mount St. Helena, elevation 4,600 feet, is situated at the intersection of Napa, Lake, and Sonoma counties. In the northern portion of the district there are many peaks exceeding six thousand feet. The range is there locally known as the Trinity mountains. Farther west are the smaller ranges known as the Scott mountains, Salmon Alps; and to the southwest the South Fork mountains and Elk Ridge. The Siskiyou mountains of Oregon extend southward into California.
The various ranges mentioned form watersheds for numerous small rivers. The streams of the eastern slope of the Coast Range drain into the Sacramento. In the north the Klamath river, and its tributary, the Trinity, drain the four northwestern counties, emptying into the Pacific ocean. The Eel River drains the Mendocino and Lake sections, flowing northwestward.
*A nautical mile is a minute of an average great circle. It is 800 feet (244 meters) more than a statute mile.
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THE CLIMATE OF CALIFORNIA
There are comparatively few lakes in this Section, the only one of any size being Clear Lake, in the center of Lake county.
The most noticeable climatic features of the coast district are the moderate temperatures, the frequent fogs and the high winds. The climate of the interior, i. e., of the valleys back from the coast, is entirely different, as will be shown later. Few extreme tem- peratures are recorded, the highest temperature at Eureka being 29.6℃, 85.2ºF on June 6, 1903, and the lowest, 6.7℃, 20ºF, January 14, 1888. A good idea of the small temperature range is obtained from the statement that the mean of the maximum temperatures for a period of ten years at Eureka was 14℃, 57ºF and the mean of the minimum temperatures, 9℃, 47ºF. The evenness of temperature is due to two factors, viz : the proximity of the ocean, and the prevailing movement of the air in these latitudes from the ocean to the land.
The winds are, as stated above, generally west, but during the winter months, owing to the approach of barometric depressions from the north, high southeast winds occur. These winter storms, known locally as "southeasters," are the most important climatic features of this section. Heavy rains accompany these storms. During the summer months there are but few disturbances. The west winds, however, in the summer months blow steadily during the afternoon hours. Occasionally during the months of April, May and June these west or northwest winds reach high velocities. In a paper entitled "Some High Wind Records on the Pacific Coast," in the Monthly Weather Review, February, 1908, McAdie and Thomas give
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HISTORY OF CALIFORNIA
records covering high velocities obtained with northwest and southeast winds. On February 25, 1902, at Point Reyes, for two hours the velocity varied from 40 to 45 meters a second, 90 to 100 miles an hour, with an extreme velocity of 46 meters a second, 103 miles an hour, or a mile in thirty-five seconds. Again, on March I, during a severe southeast gale there is a record of one mile in a little less than thirty seconds; and for five minutes, including the time of the extreme velocity, the miles averaged less than thirty-four seconds, or at the rate of 48 meters a second, 107 miles an hour. From May 15th to 20th, 1902, high northwest winds prevailed along the entire coast. At Point Reyes light, for the forty-eight hours ending midnight, May 18th the average velocity of the wind was 32 meters a second, 72 miles an hour. For the last twenty-four hours of this period the average velocity was 35 meters a second, 78 miles an hour, for the last twelve hours, 84 miles, and for the last six hours, 88 miles. The greatest wind movement recorded in any one hour was 164 kilometers, 102 miles. The maximum velocity for the storm was 49 meters a second, 110 miles an hour, at 8:50 p. m., May 18, and the extreme velocity 120 miles, at 8:38 p. m. The record of the whole period is complete and legible and of the 7,565 kilometers 4,701 miles shown, only 27 kilometers, 17 miles are interpolated, owing to the fact that the anemometer cups were carried away and this interval elapsed before a new set of cups could be put in place. The feat was performed by W. W. Thomas, at a time when the wind was blowing at the rate of 41 meters a second, 91 miles per hour.
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THE CLIMATE OF CALIFORNIA
The writer has found a reference on the old forecast charts at San Francisco to a record of 48 meters a second, 108 miles an hour from the southeast at Cape Mendocino, on January 22, 1886, at 7 A. M. There was also a note that a maximum velocity of 64 meters a second, 144 miles an hour from the southeast occurred at Cape Mendocino, on January 20, 1886.
In the paper referred to above can be found wind records for San Francisco, Point Lobos, Mount Tamal- pais, Point Reyes, and a number of interesting accounts of the velocities experienced at sea by masters of various steamships and sailing vessels.
The month of May is as a rule the month of maximum air movement. A good illustration of the duration and strength of this northwest wind is afforded by the following table, showing velocities during May, 1903:
WIND MOVEMENT FOR MONTH
Stations in California
Total for month
Average daily
Greatest in 24 hours
Greatest hourly movement
Point Reyes Light
24,072
776
1,673
88
Mount Tamalpais
16,871
544
1,189
78
San Francisco
10,040
324
517
34
Point Lobos
15,43I
498
929
60
Southeast Farallon
17,33I
559
1,185
58
A distinctive feature of the coast climate is the sea fog. The fog belt extends along the entire coast. During summer afternoons the depth of the fog stratum varies from 30 to 518 meters, 100 to 1,700 feet. Fre- quently the lower level of the fog stratum is 30 meters, 100 feet, or less above the sea or ground surface. Experiments in the vicinity of Mount Tamalpais
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HISTORY OF CALIFORNIA
indicate an average summer afternoon temperature of 27°C, 81ºF, for the levels 2,300 feet, 700 meters, and above. At saturation this would mean over 11,000 grains weight of moisture per thousand cubic feet of space. The temperature at sea level is about 13°℃, 55°F. At saturation this would mean nearly 4,900 grains of moisture per thousand cubic feet of space. The condition is therefore entirely different from some of the well-known fog formations on the Atlantic coast, where warm water supplies the necessary vapor, and fogs form when the north or northwest winds of lower temperature than the water favor condensation .* Kite experiments indicate that at the 1,000-meter, 3,280-foot level on summer afternoons there is a moderately strong flow of air from east to west. It would seem as if the heated air of the great valley, or some portion of it, moved seaward above the level of the incoming or east flow of the surface draught.
The climate of the counties back from the coast is, as previously stated, entirely different from the coast climate. These inland valleys are sheltered from the ocean winds and show a marked difference in tempera- ture amplitude, and in humidity. While on summer afternoons the coast sections are cool and foggy, the interior sections are warm, dry, and with little wind stirring unless the wind is from the north, in which case it may be strong. A fair idea of the climate of the interior may be obtained from the records of the station at Upper Lake, kept by Charles Mifflin Ham- mond, cooperative observer, for a period of more than
*There are, of course, other fog formations where warm south winds blow over cool water surfaces.
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THE CLIMATE OF CALIFORNIA
twenty-five years. A temperature of 43℃, 109ºF has been recorded once, July 31, 1909, and temperatures of 41ºC, 105ºF several times during midsummer months. The lowest temperature ever recorded was 9℃, 16ºF, on December 18, 1908.
NORTHEASTERN CALIFORNIA
This section includes the northeastern counties, lying east of an imaginary line through the foothill section of the Coast Range and south to a line drawn from the northern side of San Francisco bay to Lake Tahoe. The counties in the district are Solano, Yolo, Sacramento, Placer, Nevada, Sutter, Colusa, Butte, Sierra, Plumas, Lassen, Shasta, Modoc, and the eastern portion of Siskiyou, Tehama, and Glenn. Practically it is the watershed of the Sacramento river and its tributaries. This is the principal river of California. The following note relating to the hydrog- raphy of the section is taken from a publication of the Weather Bureau, "Climatological Data of the United States by Sections" (Bulletin W) Data, Section 15:
"The portion of the drainage basin above Red Bluff, California, extends from the Trinity Mountains on the west to the Warner Mountains, near the California-Nevada state line, on the east. The watershed on the west from the Trinity Mountains is com- paratively narrow, being only from ten to thirty-five miles in width, and furnishes a very small portion of the discharge of this river; but from the east, Pit River, which is the most important tributary, drains a large area extending about 120 miles east from Sacramento River between Mount Shasta on the north and Lassen Peak on the south. The greater portion of this basin is composed of lava and shows other evidence of volcanic activity, such as volcanic cones and craters. Nearly all the streams tributary to
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HISTORY OF CALIFORNIA
Pit River have their origin in large springs, many of which dis- charge several hundred second-feet. The most important tribu- tary of the Pit is McCloud River, draining the southeastern slope of Mount Shasta. It derives its waters principally from the melting of the snow on the high elevations of this mountain. The western portion of the watershed extending along the Trinity Range is well timbered, as is also that portion of the drainage area in the Sierra Nevada lying between Mount Shasta and Lassen Peak. Farther east, however, there is little or no forest covering, and the country is used extensively for pasturage."
The most prominent feature of the section is Mount Shasta, elevation formerly given as 14,380 feet, recently (1914) changed by the U. S. Geological Survey to 14,168 feet. The height generally given in atlases, school geographies, railway folders, etc., namely 14,444 feet is not correct. Shasta is one of the three great peaks on the Pacific coast south of Alaska, namely Mount Whitney, (14,502), Mount Ranier (14,408), and Mount Shasta.
South of Shasta lies Lassen Peak, elevation 3,184 meters, 10,437 feet. To the east and north is a large area extending to the Warner mountains with an average elevation of from four to five thousand feet. The most prominent peaks in this range are, Bidwell, 2,606 meters, 8,551 feet; Fandango, 2,392 meters, 7,848 feet; Cedar, 2,532 meters, 8,308 feet; Warren, 2,846 meters, 9,668 feet; and Eagle, 3,025 meters, 9,934 feet.
In the area between the Cascade Range and Warner Range are numerous lakes, of which the best known are Lower Klamath, Tule, Clear, and Goose lakes.
It is of some importance to understand clearly the orography of the district in order to obtain a better
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THE CLIMATE OF CALIFORNIA
comprehension of certain well-marked climatic features. It is essentially a district of local climates, one in which marked differences are found in short distances and where the general air drainage system is modified by surface conditions. The terms northern and southern do not apply in describing the climate of this section, because the isotherms run north and south. Thermal conditions depend largely upon elevation and the sheltering influence of the mountains. A more appro- priate classification of climate is that generally adopted by horticulturists, in which there are three general divisions, viz: valley, foothill and mountain. Pro- fessor E. J. Wickson, in the opening chapter of his book "California Fruits," aptly says:
"In climatic conditions affecting horticulture we have in California almost an epitome of the whole United States, with added climatic characters peculiarly our own."
In the summer months the general movement of the air is from the south. This is due to the prevailing westerly winds of these latitudes, so noticeable along the coast. The Coast Range acts as a barrier to the eastward flow of the air, and from observations made with kites and the study of the motion of the lower clouds it would appear that the surface current from the west during summer months is comparatively shallow and indeed is hardly noticeable above the 1,000 meter, 3,280 feet level. Some of this surface wind passes freely through the gap in the mountains, i. e., through the Golden Gate, and is deflected north in the Sacramento valley. This constitutes the well- known south wind felt nearly every summer night and which materially moderates the heat of the valley.
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HISTORY OF CALIFORNIA
During the long summer, mid-day, and afternoon temperatures are high. There is, for example, during the month of July, a difference of 8℃, 15ºF, or more in the mean temperature of Sacramento and San Francisco; and a difference of 13ºC, 25°F, between the mean temperature of San Francisco and Red Bluff. The temperatures are: San Francisco, 14.6℃, 57.3ºF; Sacramento, 22.5℃, 72.5°F; Red Bluff, 27.8℃, 82.1ºF. There are probably few localities in the world where there exists so marked a gradient in surface temperature. During the winter months the differ- ences are less marked and there is practically the same temperature at the northern and the southern end of the valley. The following figures give the mean temperature for January: San Francisco, 9.7℃, 49.5°F; Sacramento, 7.6℃, 45.6ºF; Red Bluff, 7.4℃, 45.4ºF. The higher temperature at San Francisco is to be explained as due chiefly to its proximity to the ocean, the same cause operating also to give the lower temperature in midsummer.
The rainfall is rather evenly distributed, and on the same level the distribution both as to intensity and frequency is comparatively uniform. There is however a marked difference in the amount of rainfall at stations close together but differing in elevation. The amount of rain increases as one goes from the floor of the valley through the foothill section and up the mountain side, reaching a maximum at a height of about 2,000 meters, 6,560 feet. The records of the stations along the line of the railroad from Sacramento to Summit, covering a period of thirty-six years, show a steady increase in the quantity of rain caught by the gages of about
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