Weather front

Weather front- is a boundary between two air masses with differing characteristics. When a weather front passes over an area, it is marked by changes in temperature, wind speed and direction, atmospheric pressure, and many times a change in the precipitation pattern. Weather fronts generally travel from west to east, guided by the jet stream. This movement is due to the spin of the Earth on its axis. Weather fronts can also be affected by geographic features like mountains and large bodies of water, especially at the lower levels of the atmosphere. There are four main types of weather fronts.

Cold front- cold fronts occur when a colder air mass approaches a warmer air mass. The colder air, being more dense, cuts a wedge under the less dense warmer air, lifting it and finally overtaking it. Cold fronts move rapidly. Strong cold fronts can set off atmospheric disturbances such as thunderstorms, tornadoes, high winds and short duration snowstorms ahead of the moving cold front and cooler, dryer weather as the front passes. Depending on the time of year, cold fronts can come in succession every 5 to 7 days. On weather maps[?], cold fronts are marked with the symbol of a blue line of triangles pointing in the direction of travel.

Warm front- warm fronts occur when a warmer air mass approaches a colder air mass . The warmer air lifts up and over the colder air. Warm fronts tend to be gentler than cold fronts. Because of this, warm fronts move slowly, gently settling over the cold front and moving it out of the way. Warm fronts bring more steady, lighter rain or snow in front of them, which can last from a few hours to several days, and warmer, dryer air as the warm front passes. On weather maps[?], warm fronts are marked with the symbol of a red line of half circles pointing in the direction of travel.

Stationary front- is a boundary between two different air masses, neither of which is strong enough to replace the other. A wide variety of weather can be found along a stationary front, but usually clouds and precipitation are found there. Stationary fronts will either dissipate after several days, or change into a cold or warm front. Stationary fronts are more numerous in the summer months. Stationary fronts are marked on weather maps[?] with an alternating red/blue line of half circles and triangles, symbolizing the dual nature of the front.

Occluded Fronts- are formed where a slower moving warm front is followed by a more rapidly moving cold front. The wedged shaped cold front eventually overtakes the warm front and pushes it aloft. The two fronts continue to move in tandem, with the line between them being the occluded front. As with stationary fronts, a wide variety of weather can be found along an occluded front, but usually they are associated with stratus clouds and light precipitation. Occluded fronts are marked on weather maps[?] with a black dotted line between closely placed cold and warm front markings.

Weather fronts are also closely associated with atmospheric pressure systems.