When a former passes end an area, it means a adjust in the weather. Countless fronts reason weather occasions such together rain, thunderstorms, gusty winds, and also tornadoes. In ~ a cold front, there might be dramatic thunderstorms. At a warm front, there may be low stratus clouds. Usually, the skies clear once the front has actually passed.

You are watching: A line of thunderstorms that forms ahead of an advancing cold front is called a ____.

What is a Weather Front?

A weather prior is a change zone in between two different air masses at the Earth"s surface. Every air fixed has distinctive temperature and also humidity characteristics. Often there is turbulence at a front, which is the borderline whereby two different air masses come together. The turbulence can cause clouds and storms.

Instead of causing clouds and also storms, some fronts just reason a change in temperature. However, some storm fronts begin Earth"s biggest storms. Tropic waves space fronts that construct in the tropical Atlantic ocean off the coast of Africa. These fronts can develop into dry storms or hurricanes if problems allow.

Fronts move across the Earth"s surface over many days. The direction of activity is frequently guided through high winds, such together Jet Streams. Landforms like mountains have the right to also readjust the course of a front.

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

Cold Front


A side watch of a cold prior (A, top) and how that is represented on a weather map (B, bottom).

Credit:Lisa Gardiner

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

As the cold former passes, winds come to be gusty. Over there is a suddenly drop in temperature, and additionally heavy rain, sometimes with hail, thunder, and also lightning. Atmospheric pressure changes from fallout’s to increasing at the front. ~ a cold prior moves v your area, girlfriend may notice that the temperature is cooler, the rain has actually stopped, and the cumulus clouds are changed by stratus and stratocumulus clouds or clean skies.

On weather maps, a cold former is stood for by a heavy blue line with filled-in triangles along it, choose in the map top top the left. The triangles are favor arrowheads pointing in the direction the the former is moving. Notification on the map that temperatures at the floor level change from warmth to cold together you cross the front line.

Warm Front


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

Credit: Lisa Gardiner

A warm front develops when a heat air mass pushes into a cooler waiting mass, presented in the photo to the ideal (A). Warm fronts often bring stormy weather together the warmth air mass at the surface ar rises over the cool air mass, making clouds and also storms. Warmth fronts move an ext slowly than cold fronts since it is more daunting for the warm air to press the cold, dense air throughout the Earth"s surface. Heat fronts often kind on the eastern side of low-pressure systems where warmer air from the southern is propelled north.

You will often see high clouds choose cirrus, cirrostratus, and also middle clouds prefer altostratus ahead of a warm front. These clouds form in the warm air that is high above the cool air. As the prior passes over an area, the clouds come to be lower, and also rain is likely. There deserve to be thunderstorms about the warmth front if the waiting is unstable.

On weather maps, the surface ar of a warm front is stood for by a solid red line through red, filled-in semicircles along it, like in the map top top the appropriate (B). The semicircles indicate the direction the the front is moving. They are on the side of the line where the prior is moving. Notice on the map the temperatures in ~ ground level are cooler in front of the front than behind it.

Stationary Front


A stationary prior is stood for on a map by triangle pointing in one direction and semicircles pointed in the other direction.

Credit:Lisa Gardiner

A stationary front forms when a cold front or warm front stop moving. This happens when two masses the air space pushing against each other, however neither is powerful enough to relocate the other. Winds punch parallel come the front rather of perpendicular can aid it stay in place.

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

Because a stationary former marks the boundary in between two wait masses, there room often differences in waiting temperature and wind ~ above opposite sides of it. The weather is often cloudy along a stationary front, and rain or snow regularly falls, specifically if the prior is in one area of low atmospheric pressure.

On a weather map, a stationary prior is shown as alternate red semicircles and also blue triangles like in the image at the left. An alert how the blue triangles allude in one direction, and the red semicircles point in the opposite direction.

Occluded Front


An occluded former is stood for on a weather map by a violet line with alternative triangles and semicircles.

Credit:Lisa Gardiner

Sometimes a cold front adheres to right behind a warm front. A heat air mass pushes into a chillier air fixed (the warm front), and also then another cold wait mass pushes into the warmth air mass (the cold front). Since cold fronts move faster, the cold prior is likely to overtake the warmth front. This is recognized as an occluded front.

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

There is regularly precipitation follow me an occluded front indigenous cumulonimbus or nimbostratus clouds. Wind transforms direction together the prior passes and the temperature one of two people warms or cools. After the former passes, the skies is commonly clearer, and the wait is drier.

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