Image from the Biodiversity Heritage Library.
Contributed by Museum of Vertebrate Zoology, University of California, Berkeley.
| www.biodiversitylibrary.org
Transcription
10.
Rotation of the earth produces east winds in the lower
Troposphere. Poleward moving air has an increased angular
velocity. There is a reverse effect equatorward at the surface
of the earth. Air moves poleward aloft. Air is deflected to
the right in the northern hemisphere, left in the southern
hemisphere at the surface in mid-latitudes (zone of
westerly winds in northern hemisphere).
N.P.
S.P.
(Surface)
N.P.
S.P.
(aloft)
cold easterlys
N.P. (high)
prevailing westerlys ->
equatorial low ->
subtropical high ->
zone of contact (low)
S.P.
(high)
(side view)
High pressure areas are maintained dynamically by the
earth's rotation. The low pressure areas are maintained both
dynamically and thermally. In winter the equatorial low
will be slightly south of the equator, and the zone of
contact shifts equatorward. (This causes rain to fall in
southern Calif. in winter, due to this area being at the edge
of the zone of contact when it is farthest south.)
Surface features break up the zonal configuration of
pressure belts -- they become divided into pressure
centers or pressure cells. Winds blow clockwise around