Dynamics of The Earth's Atmosphere
What causes the air to move?The heat of the sun on the Earth's surface warms the nearby air. This warm air becomes buoyant and rises because it is less dense than higher cooler air. This sets up cells of up and down convecting (rotating) air.
Earth's Rotation
Although it doesn't feel like it, the earth is spinning. The
equator travels at 1100 mi/hr, while the poles barely move.
The Coriolis drift is best shown by trying to draw a
straight line on a globe downward from the north pole while the globe is rotating.
The line curves depending on which way the Earth rotates, the
speed it rotates, and whether the wind is traveling Toward or Away
from the Equator.
Mixing Cells on a rotating Earth
Now things get complicated. You have cells of moving air moving
OVER a rotating object, the Earth! Winds trying to move towards the Equator
are 'left behind', while winds moving AWAY from the equator are going too fast
towards the east. The mixing cells end up moving diagonal. Rising air is
usually damp, while cool, falling air is usually very dry. Note the effect
on vegetation in Africa
