Types of wind

Global pressure movement

When the pressure gradient force would be the only force that influences wind the global pressure movement would be quite simple.
Wind streams would be like the image below. This is of course not true, you will learn all about this in the following sections.
However, this basic model shows how the earths wind streams develop. The global winds are displayed on the right.

Equator
The equator is the warmest area on earth. Air rises and cools down slowly. It travels 3000km (1900miles), and then it comes down.
These circles, in which wind moves are called Hadley cells, after George Hadley (1686-1768) who described them first in 1753.
35º
This causes a low pressure system at 3000km from the equator, 35 degrees North and South. The cooled air at the high pressure system wants to go to a warm area to replace rising air, the equator.
60º
However, not all of the cool air goes right to the equator, one half is on the way to another warm area. Warm gulfstreams at sea travel to the North and South, around 60 degrees.
This circulations in air between 30 and 60 degrees are called Ferrelcells, after William Ferrel. He discovered them in 1856. This warm air at 60 degrees North and South rises, half goes to the 35 degrees section, the other half goes to a high pressure system at the poles.
Poles
The poles are cold, so air stays at the ground, thus forming a high pressure system. The cold air moves to the low pressure system at 60º.

A force created by difference in pressure. This triggers the initial movement of air.
See also: Pressure gradient