California (source: Encyclopedia Britannica 1911 Edition)
This condition of things is not so marked as one goes inward from the coast; yet everywhere save in the high mountains the winters are comparatively mild. In the third place, the division of the year into two seasons—a wet one and a dry (and extremely dusty) one--marks this portion of the Pacific Coast in the most decided manner, and this natural climatic area coincides almost exactly in its extension with that of California; being truly characteristic neither of Lower California nor of the greater part of Oregon, though more so of Nevada and Arizona. And finally, in the fourth-place, except on the coast the disagreeableness of the heat of summer is greatly lessened by the dryness of the air and the consequent rapidity of evaporation. Among the peculiarities of Californian climate it is not one of the least striking that as one leaves the Sacramento or San Joaquin plains and travels into the mountains it becomes warmer, at least for the first 2000 or 3000 ft. of ascent. Along both the Coast Range and the Sierra considerable rainfall is certain, although, owing to the slight snow accumulations of the former, its streams are decidedly variable. A heavy rain-belt, with a normal fall of more than 40 in., covers all the northern half of the Sierra and the north-west counties; shading off from this is the region of to-2o in. fall, which covers all the rest of the state save Inyo, Kern and San Bernardino counties, Imperial county and the eastern portion of Riverside county; the precipitation of this belt is from o to to in. In excessively dry years the limits of this last division may include all of the state below Fresno and the entire Central Valley as well. In the mountains the precipitation increases with the altitude; above 6000 or 7000 ft. it is almost wholly in the form of snow; and this snow, melting in summer, is of immense importance to the state, supplying water once for placer mining and now for irrigation. The north-west counties are extremely wet; many localities here have normal rainfalls of 6o-7o in. and even higher annually, while in extreme seasons as much as r25 in. falls. Along the entire Pacific Coast, but particularly N. of San Francisco, there is a night fog from May to September. It extends but a few miles inland, but within this belt is virtually a prolongation of the rainy season and has a marked effect on vegetation. Below San Francisco the precipitation decreases along the coast, until at San Diego it is only about io in. The south-east counties are the driest portions of the United States. At Ogilby; Volcano, Indio and other stations on the Southern Pacific line the normal annual precipitation is from 1.5 to 2.5 in.; and there are localities near Owen's lake, even on its very edge, that are almost dry. For days in succession when it storms along the Southern -California coasts and dense rain clouds blow landwards to the mountains, leaving snow or rain on their summits, it has been observed that within a few miles beyond the ridge the contact of the desert air dissipates the remaining moisture of the clouds. into light misty masses, like a steam escape in cold air. The extreme heat of the south-east is tempered by the extremely low humidity characteristic of the Great Basin, which in the interior of the two southernmost counties is very low. The humidity of places such as Fresno, Sacramento and Red Bluff in the valley varies from 48 to 58. Many places in northern, southern, central, mountain and southern coastal California normally have more than 200 perfectly clear days in a year; and many in the mountains and in the south, even on the coast, have more than 250. The extreme variability in the amount of rainfall is remarkable.' The effects of a season of drought on the dry portions of the state need not be adverted to;, and as there is no rain or snow of any consequence on the mountains during summer, a succession of dry seasons may almost bare the ranges of the accumulated stock ' During the interval from 185o to 1872 the yearly rainfall at San Ftancisco ranged from 11.37 to 49.27 in.; from 1850 to 1904 the average was 22.74, and the probable annual variation 4 in.of previous winter snows, thus making .worse what. is already bad. The Colorado desert (together with the lower Gila - Valley of Arizona) is the hottest part of the United States.