When a prior passes end an area, it way a readjust in the weather. Numerous fronts reason weather occasions such as rain, thunderstorms, gusty winds, and tornadoes. In ~ a cold front, there may be dramatic thunderstorms. At a heat front, there might be short stratus clouds. Usually, the skies clear when the front has passed.

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What is a Weather Front?

A weather prior is a transition zone between two various air masses at the Earth"s surface. Every air massive has distinct temperature and also humidity characteristics. Frequently there is disturbance at a front, i beg your pardon is the borderline whereby two different air masses come together. The disturbance can cause clouds and storms.

Instead of causing clouds and also storms, some fronts just reason a change in temperature. However, some storm fronts start Earth"s largest storms. Tropic waves room fronts that construct in the tropical Atlantic s off the shore of Africa. This fronts can develop into tropic storms or hurricanes if problems allow.

Fronts move throughout the Earth"s surface ar over many days. The direction of motion is frequently guided by high winds, such as Jet Streams. Landforms like mountains can also readjust the route of a front.

There are 4 different varieties of weather fronts: cold fronts, heat fronts, stationary fronts, and occluded fronts.

Cold Front


A side view of a cold prior (A, top) and how the is stood for on a weather map (B, bottom).

Credit:Lisa Gardiner

A cold front creates when a cold air mass pushes into a warmer air mass. Cold fronts can produce dramatic transforms in the weather. They move fast, as much as twice as rapid as a warmth front. Together a cold former moves right into an area, the more heavier (more dense) cool air pushes under the lighter (less dense) heat air, bring about it to rise up into the troposphere. Lifted warmth air front of the prior produces cumulus or cumulonimbus clouds and also thunderstorms, like in the picture on the left (A).

As the cold front passes, winds come to be gusty. There is a suddenly drop in temperature, and likewise heavy rain, occasionally with hail, thunder, and lightning. Atmospheric pressure changes from falling to rising at the front. After a cold former moves v your area, friend may notification that the temperature is cooler, the rain has stopped, and also the cumulus clouds are changed by stratus and stratocumulus clouds or clear skies.

On weather maps, a cold former is represented by a hard blue line with filled-in triangles follow me it, like in the map on the left. The triangles are favor arrowheads pointing in the direction the the prior is moving. An alert on the map that temperatures at the soil level readjust from warmth to cold as you cross the former line.

Warm Front


A side see of a heat front (A, top) and how that is represented on a weather map (B, bottom).

Credit: Lisa Gardiner

A warmth front forms when a warmth air fixed pushes right into a cooler wait mass, displayed in the image to the right (A). Warmth fronts often carry stormy weather together the warmth air mass in ~ the surface rises over the cool waiting mass, making clouds and storms. Heat fronts move an ext slowly than cold fronts because it is more complicated for the warm air to press the cold, dense air across the Earth"s surface. Warm fronts often type on the east side that low-pressure systems where warmer wait from the south is pushed north.

You will regularly see high clouds prefer cirrus, cirrostratus, and also middle clouds choose altostratus ahead of a heat front. These clouds kind in the warm air the is high above the cool air. As the prior passes over an area, the clouds become lower, and also rain is likely. There have the right to be thunderstorms approximately the warm front if the air is unstable.

On weather maps, the surface place of a warm front is represented by a solid red line through red, filled-in semicircles follow me it, favor in the map ~ above the ideal (B). The semicircles suggest the direction the the prior is moving. They room on the side of the line whereby the prior is moving. An alert on the map that temperatures at ground level are cooler in prior of the front than behind it.

Stationary Front


A stationary front is stood for on a map by triangle pointing in one direction and also semicircles spicy in the other direction.

Credit:Lisa Gardiner

A stationary front creates when a cold front or warmth front stop moving. This happens once two masses that air space pushing versus each other, yet neither is powerful enough to relocate the other. Winds punch parallel to the front rather of perpendicular can assist it remain in place.

A stationary front might stay put for days. If the wind direction changes, the front will certainly start relocating again, ending up being either a cold or warmth front. Or the front might break apart.

Because a stationary former marks the boundary between two waiting masses, there are often differences in air temperature and also wind on opposite sides of it. The weather is frequently cloudy along a stationary front, and rain or snow regularly falls, specifically if the front is in an area of low atmospheric pressure.

On a weather map, a stationary prior is presented as alternative red semicircles and blue triangles choose in the picture at the left. Notice how the blue triangles suggest in one direction, and also the red semicircles allude in the contrary direction.

Occluded Front


An occluded prior is represented on a weather map through a purple line with alternating triangles and semicircles.

Credit:Lisa Gardiner

Sometimes a cold front complies with right behind a warmth front. A warmth air mass pushes right into a chillier air massive (the heat front), and then another cold wait mass pushes right into the warm air fixed (the cold front). Due to the fact that cold fronts move faster, the cold prior is likely to overtake the warmth front. This is known as one occluded front.

At an occluded front, the cold waiting mass indigenous the cold front meets the cool air the was front of the heat front. The heat air rises as these air masses come together. Occluded fronts usually form around locations of short atmospheric pressure.

There is often precipitation follow me an occluded front from cumulonimbus or nimbostratus clouds. Wind changes direction as the prior passes and also the temperature one of two people warms or cools. After the front passes, the sky is generally clearer, and the air is drier.

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On a weather map, shown to the left, an occluded former looks like a violet line with alternative triangles and also semicircles pointing in the direction that the front is moving. It end at a low push area displayed with a huge ‘L’ on the map, starts at the other finish when cold and also warm fronts connect.