Air pressure is the pressure exerted by the weight of air on the earth's surface. As we go up the layers of the atmosphere, the pressure falls rapidly. The air pressure is highest at the sea level and decreases with height. Horizontally the distribution of air pressure is influenced by the temperature of the air at a given place. In areas where the temperature is high the air gets heated and rises. This creates a low-pressure area. In areas having lower temperature, the air is cold, hence, it is heavy. Heavy air sinks and creates a high-pressure area.