Balance is Key

• Smooth, stable and stagnant air is a relatively rare phenomenon in the Earth's atmosphere. Some areas of air, which may be as large as several hundred miles or as small as a single county, are under greater pressure than the air in surrounding areas; this arrangement of air under great pressure is known as a high-pressure area, and the surrounding areas of relatively lower pressure are known as low-pressure areas. In an attempt to maintain balance, air naturally flows out of high-pressure areas and into low-pressure areas, creating a flow of air generally recognized as wind.
  
  

Pressure Changes

• As air flows from a high-pressure area to one of lower atmospheric pressure, other changes are also occurring. Large metropolitan areas, for example, create a tremendous amount of heat as the sun shines on glass, steel and asphalt surfaces. This heated air rises quickly, creating a surface-level area of low pressure. In seaside communities, the absorption of heat by the land occurs at a quicker pace than absorption by the water, creating a natural area of low pressure. As the sun sets, the land releases its stored heat much more quickly than the nearby water, creating an area of heavier air over the land and lighter, upward-flowing air over the water.
  
  

Air Still Tries to Maintain Balance

• As the numerous changes in air pressure change throughout the day, air flows back and forth between the areas of high and low pressure. Since the movement of air is never able to establish a complete equality in the atmosphere--due to the myriad factors in play--the air continually flows back and forth from one area of pressure to another. As the areas of pressure change, the wind changes direction as air rushes to the new area of low pressure. In addition, areas of significantly lower pressure allow air to rush in more quickly, creating a variance not only in wind direction, but in the speed at which it moves.