How Does Air Pressure Affect The Weather?

Since air at a higher temperature is less dense than the cooler air over another area, it rises. This movement, in turn, generates differences in pressure between different areas.

A barometer, which measures the weight of atmosphere above it, will show a lower pressure under a rising column of warm air, which displaces the cooler, relatively more dense air above it. On the other hand, a descending column of cool air will cause higher pressure below it. The pressure difference at the surface causes a wind to blow from the region of higher pressure toward that of lower pressure. It is similar to what happens when an inflated balloon is opened at one end. The high-pressure air inside rushes out into the surrounding area of lower pressure. The greater the pressure difference, the stronger the wind. This principle operates on a global scale.

Warm air near the equator rises and moves toward the poles. In turn, the cooler polar air is drawn beneath, toward the equator. The earth's rotation diverts these currents into prevailing easterly and westerly winds at different latitudes and altitudes.

These global movements of air masses in different directions generate turbulent motions where the main streams brush against each other. There are additional effects from topography—the irregular outlines of continents and the complex patterns of mountains and plains, deserts and forests.