Chapter 1 (LECTURE) Flashcards
Circulations must be much larger in order to
be affected by rotation of the Earth. One manifestation of this is that land/sea breezes penetrate further inland in Tropics than in midlatitudes.
where U is the
characteristic wind speed
L is the
characteristic horizontal length scale.
Poleward of 30° the Rossby number is
small enough that the geostrophic wind and actual wind are fairly close
Equatorward of 30° the Rossby number is
no longer small, and the geostrophic and actual wind can differ greatly, especially as the Equator is approached.
On the planetary scale, where L ~
107 m, the Rossby number does remain small through most of the Tropics.
• Therefore, quasi-geostrophic theory may be carefully applied to planetary- scale circulations such as the monsoon, the Walker circulation, etc.
Pressure gradients are also quite weak in the Tropics, except in
tropical cyclones.
Though the actual gradient level varies with
time and location,
Inflow and Outflow - Pure inflow and outflow doesn’t usually appear on the synoptic scale. Usually it is accompanied by
rotation, and so appears in conjunction with cyclones and anticyclones
Cyclones and anticyclones - represent closed circulations, which would have closed isobars on a pressure map. They are usually accompanied by either inflow or outflow, and so
purely circular or closed streamlines are not usually analyzed.
Areas of inflow and outflow with little associated rotation appear on streamline charts in
deep Tropics
Strong anticyclones are not common in deep Tropics, because
they would have negative absolute vorticity.
Due to the superposition of the 24 and 8-hr period waves with the 12-hr wave,
the morning pressure maximum is slightly larger than nighttime maximum, while the afternoon minimum is slightly lower than the early morning minimum.
the daily range of the pressure variation can vary with
cloudiness, water vapor content, and surface moisture.
The asymmetry of the maximums and minimums is also more pronounced
over
land
