In the Northern Hemisphere, a low pressure area always creates a wind that blows counterclockwise around the low. The high pressure area creates a wind that blows clockwise around the high. This wind around highs and lows plays a major role in transporting warm air masses from the souh and cold air masses from the north. The transportation of air masses creates what are called fronts. Students will learn about two types of fronts on the weather map.
Fronts are lines marking the leading edge of a change in air mass or temperature.
A leading edge of an air mass moves forward along a weather front. When we see an approaching front, we know that the air and temperatures behind the front can be much different form the present air mass. Fronts are usually connected to a rotation low pressure system that is producing rain or snaow. Fronts also help to lift and cool the air, creating clouds and precipitation. Air rotating counterclockwise around the low brings warm air from the south ahead of the low and cooler air from the north behind the center of the low.