Because the lifting is very gradual and steady, generally wide spread and light intensity precipitation develops ahead of a warm front. A Closer Examination of the Animation: Initially, a warm air mass in yellow nudges against a colder air mass in blue ahead of it, separated from each other by the warm front. The lighter warm moist air behind the front is lifted upward and "overrides" the colder air. A front may become stationary if an air mass is stopped by a barrier, such as a mountain range.
A stationary front may bring days of rain, drizzle, and fog. Winds usually blow parallel to the front, but in opposite directions. After several days, the front will likely break apart. When a cold air mass takes the place of a warm air mass, there is a cold front. Imagine that you are standing in one spot as a cold front approaches.
Along the cold front, the denser, cold air pushes up the warm air, causing the air pressure to decrease. If the humidity is high enough, some types of cumulus clouds will grow. High in the atmosphere, winds blow ice crystals from the tops of these clouds to create cirrostratus and cirrus clouds. At the front, there will be a line of rain showers, snow showers, or thunderstorms with blustery winds. A squall line is a line of severe thunderstorms that forms along a cold front. Behind the front is the cold air mass.
This mass is drier so precipitation stops. The weather may be cold and clear or only partly cloudy. Winds may continue to blow into the low pressure zone at the front.
The weather at a cold front varies with the season. Along a warm front , a warm air mass slides over a cold air mass. Rain and even thunderstorms can form as the moisture in the warm air mass rises, cools, and condenses. With a cold frontal passage, the winds will typically shift from the south to the west or north. As the front moves through, cool, fair weather is likely to follow. The temperatures behind a cold front vary depending on the type of air mass moving in. A polar air mass will bring in cold air in the winter and cool air at other times.
An Arctic air mass will be associated with bitterly cold temperatures in the winter. An air mass coming off high latitude ocean areas will be unusually cold in summer but more moderate in winter.
If the cold front is highly unstable, cumulonimbus clouds producing thunderstorms commonly form along or ahead of the front. Anvil cirrus clouds may spread a considerable distance downwind from the thunderstorms. The other cloud types associated with a cold front depend on atmospheric conditions such as air mass stability and wind shear. 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.
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