Air masses are always in motion, bringing with them, different types of weather conditions. The transition between two different types of air masses is called a front. There are four basic types of fronts, and the weather associated with them varies.
1. Cold Front
A cold front is the leading edge of a colder air mass. Temperatures will usually change rapidly over a short distance. Also, there is a sharp change in moisture content; higher moisture content ahead of the front and lower moisture content behind it. Shifts in wind direction are significant in identifying a cold front. Ahead of a cold front, winds will be southerly before turning toward the west as the front approaches. After the cold front arrives, winds will become northerly. Thunderstorms sometimes develop ahead of these fronts as the warm air ahead of the front rises over the colder air.
2. Warm Front
Warm fronts tend to move slower than cold fronts and are the leading edge of warm air moving northward. Before the front passes, winds are easterly. Cloud cover may be heavy ahead of the front with rainfall chances increasing as it approaches. Afterwards, winds will usually remain southerly or become southwesterly, and temperatures will warm rapidly with clouds clearing. With the warm air comes higher humidity too.
3. Stationary Front
Another type of front that can be found on a weather map is stationary in nature. In a front of this kind, neither the cold air mass nor the warm air mass is moving. Winds tend to blow along it in opposing directions on each side. Conditions along the front are clear and dry, however, if moisture is available near the front, clouds and light precipitation may develop.
4. Occluded Front
An occluded front occurs when a cold front overtakes a warm front. There are both cold and warm occlusions. In a cold occlusion, the colder air is found behind the front. Conversely, a warm occlusion is characterized by warmer air located behind the front. Winds are either from the east or south before the front passes. After the front, winds shift from the west or northwest.
Understanding the various types of fronts can help you know what kind of weather to expect when looking at a weather map. This knowledge can help predict where they may go and how areas near the front will be impacted regarding temperatures, winds, and precipitation.