n easterly direction, and
in consequence the climate of the western coast of North America
is not marked by such extremes in winter and summer as are the
interior and the eastern sections. It is also surprising to find
how nearly alike the average winter and summer temperature is at San
Francisco. It is also surprising to note that the average temperature
of Seattle differs so little from that of San Diego, although these
two places are separated by sixteen degrees of latitude.

In some places the climatic conditions which we should naturally
expect seem to be reversed. Oranges are grown in the Great Valley
of California as far north as Red Bluff, and actually ripen a month
sooner than they do near Los Angeles, five hundred miles farther
south. The early ripening of fruits in the Great Valley may be
explained by the presence of the inclosing mountain ranges: the
Sierra Nevada mountains upon the northeast shut off the cold winds
of winter, while the Coast ranges upon the west break the cool
summer winds which come from off the Pacific.

Another interesting fact connected with the climate of the West is
the influence exerted by the direction of the mountain ranges. As
these ranges usually lie across the path of the prevailing winds,
their tempering influence is lost much more quickly than it otherwise
would be. West of the Coast ranges the summers are cool and the
winters are warm. Upon the eastern side of these mountains the
winters are somewhat cooler and the summers very much warmer. In
the dry, clear air of the desert valleys, far from the ocean, the
daily range in temperature is sometimes as great as fifty degrees,
while the winters are cool and the summers unbearably hot.

We all know how much cooler a hill-top is than a valley upon a
summer day. Where the mountains rise abruptly to a great height, as,
for example, does the San Bernardino Range of southern California,
one can stand among stunted plants of an arctic climate and look
down upon orange orchards where frost rarely forms. Mount Tamalpais,
a peak of the Coast Range north of San Francisco, has an elevation
of nearly three thousand feet. The summer temperature upon this
mountain forms an exception to the general rule, for while the
lowlands are buried in chilling fog, the air upon the summit is
warm and pleasant.

[Illustration: FIG. 111.--ORANGE ORCHARDS CLOSE UNDER SNOW-CAPPED
PEAKS

Highlands, California]

The north and south mountain ranges not