When a former passes over an area, it means a adjust in the weather. Countless fronts cause weather events such as rain, thunderstorms, gusty winds, and also tornadoes. At a cold front, there might be dramatic thunderstorms. In ~ a warm front, there might be low stratus clouds. Usually, the skies clear as soon as the front has passed.

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What is a Weather Front?

A weather prior is a transition zone in between two different air masses at the Earth"s surface. Each air fixed has unique temperature and humidity characteristics. Regularly there is disturbance at a front, i m sorry is the borderline whereby two different air masses come together. The turbulence can reason clouds and storms.

Instead of bring about clouds and storms, some fronts just reason a readjust in temperature. However, some storm fronts begin Earth"s largest storms. Tropic waves room fronts that construct in the tropical Atlantic ocean off the coastline of Africa. This fronts can build into tropic storms or hurricanes if problems allow.

Fronts move throughout the Earth"s surface ar over lot of days. The direction of activity is frequently guided by high winds, such together Jet Streams. Landforms choose mountains have the right to also adjust the path of a front.

There are four different types of weather fronts: cold fronts, warm fronts, stationary fronts, and occluded fronts.

Cold Front


A side see of a cold former (A, top) and how that is stood for on a weather map (B, bottom).

Credit:Lisa Gardiner

A cold front forms when a cold air mass pushes into a warmer wait mass. Cold fronts can develop dramatic transforms in the weather. They move fast, up to twice as quick as a warmth front. As a cold prior moves right into an area, the heavier (more dense) cool air pushes under the lighter (less dense) warmth air, causing it to increase up right into the troposphere. Lifted heat air front of the former produces cumulus or cumulonimbus clouds and thunderstorms, like in the image on the left (A).

As the cold front passes, winds become gusty. Over there is a sudden drop in temperature, and additionally heavy rain, periodically with hail, thunder, and also lightning. Atmospheric pressure changes from falling to increasing at the front. ~ a cold prior moves v your area, friend may notification that the temperature is cooler, the rain has stopped, and the cumulus clouds are replaced by stratus and also stratocumulus clouds or clear skies.

On weather maps, a cold prior is represented by a hard blue line with filled-in triangles along it, favor in the map ~ above the left. The triangles are prefer arrowheads pointing in the direction the the former is moving. Notice on the map the temperatures in ~ the soil level change from warm to cold as you overcome the front line.

Warm Front


A side view of a warm front (A, top) and how it is stood for on a weather map (B, bottom).

Credit: Lisa Gardiner

A warm front creates when a heat air mass pushes right into a cooler wait mass, shown in the photo to the appropriate (A). Warmth fronts often lug stormy weather as the heat air mass in ~ the surface ar rises over the cool air mass, making clouds and storms. Heat fronts move much more slowly than cold fronts because it is more difficult for the warmth air to push the cold, thick air throughout the Earth"s surface. Warmth fronts often form on the east side of low-pressure systems where warmer air from the south is pushed north.

You will often see high clouds choose cirrus, cirrostratus, and also middle clouds choose altostratus ahead of a warm front. This clouds form in the warm air that is high over the cool air. As the former passes end an area, the clouds become lower, and also rain is likely. There can be thunderstorms roughly the warm front if the air is unstable.

On weather maps, the surface location of a heat front is represented by a solid red line with red, filled-in semicircles follow me it, favor in the map ~ above the ideal (B). The semicircles show the direction the the prior is moving. They space on the side of the line where the front is moving. Notice on the map that temperatures in ~ ground level are cooler in prior of the front than behind it.

Stationary Front


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

Credit:Lisa Gardiner

A stationary front forms when a cold prior or warm front stop moving. This happens as soon as two masses the air room pushing against each other, but neither is powerful enough to move the other. Winds punch parallel come the front instead of perpendicular can assist it stay in place.

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

Because a stationary prior marks the boundary in between two wait masses, there room often distinctions in wait temperature and also wind on opposite sides of it. The weather is often cloudy follow me a stationary front, and rain or snow frequently falls, especially if the former is in one area of low atmospheric pressure.

On a weather map, a stationary former is displayed as alternating red semicircles and blue triangles favor in the photo at the left. Notice how the blue triangles allude in one direction, and also the red semicircles suggest in the contrary direction.

Occluded Front


An occluded front is stood for on a weather map by a violet line with alternating triangles and also semicircles.

Credit:Lisa Gardiner

Sometimes a cold front adheres to right behind a warm front. A warm air massive pushes right into a chillier air fixed (the warm front), and also then an additional cold air mass pushes into the warmth air massive (the cold front). Due to the fact that cold fronts relocate faster, the cold prior is most likely to overtake the warmth front. This is recognized as an occluded front.

At an occluded front, the cold waiting mass indigenous the cold front meets the cool air the was ahead of the warm front. The warmth air rises together these waiting masses come together. Occluded fronts usually kind around locations of low atmospheric pressure.

There is often precipitation along an occluded front indigenous cumulonimbus or nimbostratus clouds. Wind transforms direction together the front passes and also the temperature either warms or cools. ~ the former passes, the sky is usually clearer, and also the air is drier.

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On a weather map, shown to the left, one occluded prior looks favor a violet line with alternate triangles and semicircles pointing in the direction the the prior is moving. It end at a low push area presented with a large ‘L’ ~ above the map, begins at the other end when cold and also warm fronts connect.