13 14 15 16 17 18 19 20 16501700175018001850190019502000 july temperature ( c) figure 7.1 13 14 15...
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Figure 7.1
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Ecological Climatology © 2008 G. Bonan
strong Pacific jet stream wellsouth of normal directs majorstorms and moisture into theSouthwest
normal Pacific jet stream
Polar jet stream north of normal blocks cold air
high pressure;temperatures above normal
persistent lowpressure; recordrains and floods
above normal temperatures in tropical Pacific
normal Polarjet stream
Low pressure
below normal temperatures in tropical Pacific
variable Pacific jet stream strengthensmarkedly toward the Pacific Northwestat times, directing major storms intothe region
low pressure area;heavy rains and floods
persistent high pressure area;very dry and warm
High pressure
variable Polar jet stream strengthensand shifts south of normal at times,producing frequent cold and storms
Figure 7.12Ecological Climatology © 2008 G. Bonan
Figure 7.14
(mm day-1)Evaporation - Precipitation
90W 60W 30W 0 30E 60E
20N
40N
60N
80N
Ecological Climatology © 2008 G. Bonan