Inactive cold fronts fast moving have an average speed of 25 knots. Occluded Fronts. A newly formed occlusion will initially move at the same speed as the cold front that overtakes the warm front. Eventually, the occluded front "wraps around" the baroclinic low as the low moves off of the frontal boundary back into the colder air. The low usually moves to the northwest, on the equatorward side of the occluded front. The position and counterclockwise flow of the low causes the occluded front to "wrap around" the low.
Cold fronts generally advance at average speeds of 20 to 25 mph. This also forces temperature differences across warm fronts to be broader in scale. In other words, a cold front is right at the leading edge of moving cold air and a warm front marks the leading edge of moving warm air. When two air masses meet together, the boundary between the two is called a weather front. With the slow-moving cold front, there is a general upward motion of warm air along the entire frontal surface and pronounced lifting along the lower portion of the front.
The lower half shows the typical upper airflow behind the front, and the upper half shows the accompanying surface weather. The boundary between two air masses is called a front. If a fast-moving cold air mass overtakes a slower-moving warm front and then continues advancing and catches another cold front, an occluded front forms.
An occluded front has cool weather with a lot of precipitation. Catastrophic weather events include hurricanes, tornadoes, blizzards, and droughts, among others. As these massively destructive and costly events become more frequent, scientific evidence points to climate change as a leading cause. While they can often be predicted, the loss of life and property take an emotional and economic toll on the community impacted. Explore these resources to teach your students about catastrophic weather events and how they impact every part of the world.
Most people think of a blizzard as a bad snowstorm, but a winter storm must meet certain criteria to be classified as a blizzard. According to the National Weather Service, a blizzard is a weather event that includes low temperatures, wind speeds greater than 56 kilometers 35 miles per hour, and a large amount of falling or blowing snow that lowers visibility to 0. These whiteout conditions can cause car accidents and people on foot to become lost.
Additionally, the colder temperatures that often follow a blizzard can put people at risk of frostbite or hypothermia.
Explore more about blizzards with this collection of resources. One of the first things you probably do every morning is look out the window to see what the weather is like. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. The skies over this barn are on the front line.
Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. Landforms like mountains can also change the path of a front. There are four different types of weather fronts: cold fronts, warm fronts, stationary fronts, and occluded fronts. A side view of a cold front A, top and how it is represented on a weather map B, bottom.
A cold front forms when a cold air mass pushes into a warmer air mass. Cold fronts can produce dramatic changes in the weather. They move fast, up to twice as fast as a warm front. As a cold front moves into an area, the heavier more dense cool air pushes under the lighter less dense warm air, causing it to rise up into the troposphere. Lifted warm air ahead of the front produces cumulus or cumulonimbus clouds and thunderstorms, like in the image on the left A.
As the cold front passes, winds become gusty. There is a sudden drop in temperature, and also heavy rain, sometimes with hail, thunder, and lightning. Atmospheric pressure changes from falling to rising at the front.
After a cold front moves through your area, you may notice that the temperature is cooler, the rain has stopped, and the cumulus clouds are replaced by stratus and stratocumulus clouds or clear skies. On weather maps, a cold front is represented by a solid blue line with filled-in triangles along it, like 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.
A side view of a warm front A, top and how it is represented on a weather map B, bottom. A warm front forms when a warm air mass pushes into a cooler air mass, shown in the image to the right A.
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