When a front passes over a room, it means a change in the weather. Many type of fronts cause weather events such as rain, thunderstorms, gusty winds, and tornadoes. At a cold front, tbelow might be dramatic thunderstorms. At a warm front, tright here might be low stratus clouds. Normally, the skies clear once the front has passed.

You are watching: On a weather map, ________ are shown by a line with triangular points on one side.

What is a Weather Front?

A weather front is a shift zone between two different air masses at the Earth"s surface. Each air mass has distinctive temperature and also humidity attributes. Often there is disturbance at a front, which is the borderline where 2 different air masses come together. The disturbance deserve to cause clouds and storms.

Instead of bring about clouds and also storms, some fronts simply cause a adjust in temperature. However before, some storm fronts start Earth"s biggest storms. Tropical waves are fronts that build in the tropical Atlantic Ocean off the coastline of Africa. These fronts can build right into tropical storms or hurricanes if problems enable.

Fronts relocate throughout the Earth"s surconfront over multiple days. The direction of movement is regularly guided by high winds, such as Jet Streams. Landdevelops like hills deserve to likewise change the route of a front.

Tright here are four various kinds of weather fronts: cold fronts, warm fronts, stationary fronts, and also occluded fronts.

Cold Front


A side watch of a cold front (A, top) and also exactly how it is represented on a weather map (B, bottom).

Credit:Lisa Gardiner

A cold front creates once a cold air mass pushes right into a warmer air mass. Cold fronts can create dramatic changes in the weather. They move rapid, up to twice as quick as a warmth front. As a cold front moves into a space, the heavier (more dense) cool air pushes under the lighter (much less dense) warm air, bring about it to increase up right into the tropospbelow. Lifted warm air ahead of the front produces cumulus or cumulonimbus clouds and thunderstorms, prefer in the picture on the left (A).

As the cold front passes, winds end up being gusty. Tbelow is a sudden drop in temperature, and also additionally hefty rain, periodically through hail, thunder, and lightning. Atmospheric pressure alters from falling to increasing at the front. After a cold front moves through your location, you might notification that the temperature is cooler, the rain has actually stopped, and the cumulus clouds are reinserted by stratus and stratocumulus clouds or clear skies.

On weather maps, a cold front is represented by a solid blue line via filled-in triangles alengthy it, choose in the map on the left. The triangles are like arrowheads pointing in the direction that the front is moving. Notice on the map that temperatures at the ground level change from warm to cold as you cross the front line.

Warm Front


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

Credit: Lisa Gardiner

A warm front creates when a warm air mass pushes into a cooler air mass, shown in the photo to the appropriate (A). Warm fronts often bring stormy weather as the warmth air mass at the surface rises above the cool air mass, making clouds and also storms. Warm fronts move more slowly than cold fronts because it is even more tough for the heat air to push the cold, thick air throughout the Earth"s surchallenge. Warm fronts frequently form on the eastern side of low-pressure devices where warmer air from the southern is puburned north.

You will regularly see high clouds like cirrus, cirrostratus, and also middle clouds favor altostratus ahead of a heat front. These clouds develop in the warm air that is high over the cool air. As the front passes over a space, the clouds become lower, and rain is most likely. Tright here can be thunderstorms approximately the heat front if the air is unsecure.

On weather maps, the surchallenge area of a heat front is represented by a solid red line with red, filled-in semicircles alengthy it, choose in the map on the best (B). The semicircles show the direction that the front is moving. They are on the side of the line wbelow the front is moving. Notice on the map that temperatures at ground level are cooler in front of the front than behind it.

Stationary Front


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

Credit:Lisa Gardiner

A stationary front creates as soon as a cold front or warm front stops relocating. This happens as soon as 2 masses of air are pushing versus each other, yet neither is powerful sufficient to relocate the other. Winds blowing parallel to the front rather of perpendicular have the right to assist it stay in area.

A stationary front may continue to be put for days. If the wind direction changes, the front will certainly start relocating again, coming to be either a cold or warmth front. Or the front may break apart.

Because a stationary front marks the boundary between 2 air masses, tbelow are frequently distinctions in air temperature and also wind on oppowebsite sides of it. The weather is regularly cloudy along a stationary front, and rain or scurrently often falls, especially if the front is in a room of low atmospheric pressure.

On a weather map, a stationary front is displayed as alternating red semicircles and also blue triangles like in the picture at the left. Notice how the blue triangles allude in one direction, and the red semicircles allude in the opposite direction.

Occluded Front


An occluded front is represented on a weather map by a purple line via alternating triangles and also semicircles.

Credit:Lisa Gardiner

Sometimes a cold front adheres to appropriate behind a warmth front. A warmth air mass pushes right into a colder air mass (the heat front), and then an additional cold air mass pushes into the heat air mass (the cold front). Due to the fact that cold fronts relocate much faster, the cold front is likely to overtake the warm front. This is recognized as an occluded front.

At an occluded front, the cold air mass from the cold front meets the cool air that was ahead of the heat front. The warmth air rises as these air masses come together. Occluded fronts normally form about locations of low atmospheric pressure.

There is regularly precipitation alengthy an occluded front from cumulonimbus or nimbostratus clouds. Wind alters direction as the front passes and also the temperature either warms or cools. After the front passes, the skies is normally clearer, and the air is drier.

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On a weather map, shown to the left, an occluded front looks favor a purple line via alternating triangles and semicircles pointing in the direction that the front is relocating. It ends at a low press location presented through a huge ‘L’ on the map, begins at the various other end when cold and also warmth fronts connect.