Geoscience Reference
In-Depth Information
13120
Storm
iGj
precip.
60 in
9840
{
Elevation
(feet)
precip.
31 in
6560
y
\`W]G
\`W]G
h
precip. 8 in
\Y[`G
\Y[`G
precip.
35 in
[\XXG
[\XXG
3280
z
Great
Basin
Sierra Nevada
Central
Valley
precip.
16 in
XY[^G
XY[^G
0
0 25 50 75 100 125
Miles from Coast
W E
f igu r e 4 . Schematic west-to-east cross-section from the California coast to the Nevada
border, showing the elevation of the Sierra Nevada and corresponding annual average levels
of precipitation across the range. (Sketch by B. Lynn Ingram.)
the windward slopes, leaving the leeward slopes and places to the east
relatively dry (see i gure 4). h is explains the relatively lush western slopes
of the mountains in the West compared to the drier and sparsely vegetated
eastern slopes and valleys beyond (see i gure 5). In this way, the landscapes
of the American West both have an inl uence on the region's weather and
are formed by it.
California spans nearly ten degrees of latitude, which results in a wide
spectrum of natural plant communities, determined largely by the rain-
fall regime. Storm systems entering California i rst encounter the Coast
Ranges and then pass through the Central Valley, move up the high
mountain ranges of the Sierra Nevada, and continue into the deserts of
the Great Basin. Northern California is the southern extension of the
lush temperate rainforests of the Pacii c Northwest, whereas Southern
California is part of the deserts of the semiarid to arid Southwest.
Nevertheless, California's moisture regime follows strict—if somewhat
unusual—patterns. h e Department of Geography at the University of
California, Berkeley, has a long history of researchers interested in cli-
mate, including Jim Parsons, who, in a personal communication with this
topic's authors, noted that the state's climate is unique because of its arbi-
trarily conceived boundaries, which outline the only area of winter rain
and summer drought in North America. h is so-called Mediterranean
climate—warm, dry summers and mild, wet winters—is a common occur-
