Download Local Winds-fact file

wind
Wind is simply air in motion, moving
from high pressure to low pressure.
Winds are described by the direction
they blow from - an easterly wind lows
from the east, a westerly from the
west. Prevailing winds (winds which
occur frequently in a particular
direction) are arranged in a series of
belts around the globe. This pattern is
the result of differences in the speed the Earth rotates
and the different amounts of solar heating it gets,
depending on where a place is between the poles and
the equator.
There are many smaller scale winds and wind
patterns produced by a number of processes.
Mountains often produce their own local winds, and
wind currents can be shaped as they are forced to rise
or funnelled through valleys, greatly increasing their
strength. As an air mass descends a mountain slope it
is compressed and becomes a warm dry wind. The
effect is most noticeable in spring when these winds
can melt snow very quickly. They are called föhn
winds in the Alps and chinook ("snow-eaters") in
western North America and they can sometimes
cause avalanches.
local winds have names
Other winds are truly local and are caused by a daily
pattern of air-flow up and down valleys.
Katabatic winds occur at night when cool air sinks
down mountain slopes and valleys. Anabatic winds
occur when sun-warmed air rises and gently flows up
mountain slopes and valleys.