The air in out atmosphere has weight, can you believe it!. The air that extends to the top of the atmosphere will always be pushing on you, that is air pressure. Air pressure changes at different places on earth's surface. When the air is heated it expands and becomes less dense then it rises, that is a low-pressure areas. In low pressure areas there is unstable weather. In high pressure areas the weather is stable, clear, and dry weather usually. There are four air pressure zones, equilateral lows, subtropical highs, sub-polar lows, polar highs. Wind and pressure work hand in hand with each other. Air pressure Affects the global wind patterns all over the world. Wind flows from high to low pressure areas. Prevailing winds are areas of the world that have winds that blow from the same direction most of the time. But the zone along the equator is calm and is called the Doldrums. The middle-latitude winds are called the Westerlies. When two air masses of midley different temperatures that is a front. Last but not least is the jet stream which is in the high upper atmosphere.