What makes fronts move

The weather at a cold front varies with the season. Along a warm front , a warm air mass slides over a cold air mass. When warm, less dense air moves over the colder, denser air, the atmosphere is relatively stable. Imagine that you are on the ground in the wintertime under a cold winter air mass with a warm front approaching.

The transition from cold air to warm air takes place over a long distance so the first signs of changing weather appear long before the front is actually over you. Initially, the air is cold: the cold air mass is above you and the warm air mass is above it. High cirrus clouds mark the transition from one air mass to the other. Over time, cirrus clouds become thicker and cirrostratus clouds form. As the front approaches, altocumulus and altostratus clouds appear and the sky turns gray.

Since it is winter, snowflakes fall. The clouds thicken and nimbostratus clouds form. Snowfall increases. Winds grow stronger as the low pressure approaches. As the front gets closer, the cold air mass is just above you but the warm air mass is not too far above that. The weather worsens. As the warm air mass approaches, temperatures rise and snow turns to sleet and freezing rain. Warm and cold air mix at the front, leading to the formation of stratus clouds and fog.

An occluded front usually forms around a low pressure system. The occlusion starts when a cold front catches up to a warm front. The air masses, in order from front to back, are cold, warm, and then cold again. Coriolis Effect curves the boundary where the two fronts meet towards the pole. If the air mass that arrives third is colder than either of the first two air masses, that air mass slip beneath them both.

If the wedge is moving into an area of warmer air, the front is called a cold front. If the wedge is retreating and warmer air is moving into an area previously occupied by cool air, the front is termed a warm front.

Figure 1 - Types of Fronts Definition Fronts are boundaries between air masses of different temperatures. Fronts are actually zones of transition, but sometimes the transition zone, called a frontal zone, can be quite sharp. There are four types of fronts that will be described below: cold front, warm front, stationary front, and occluded front.

Not all of these patterns may be obvious or even occur, but these are some signs. This results from the fact that low-level southerly winds in the "warm sector" of the cyclone rise up and over the cooler, more dense air at the surface located north of the warm front. The lifting leads to saturation, cloud formation, and, ultimately, to some form of precipitation.

Stationary Fronts Stationary front- a front that does not move or barely moves. Figure 4 - Development of an Occluded Front Occluded Fronts Because cold fronts move faster than warm fronts, they can catch up to and overtake their related warm front. When they do, an occluded front is formed. The weather ahead of the cold occlusion is similar to that of a warm front while that along and behind the cold occlusion is similar to that of a cold front. Fronts are zones of transition between two different air masses.

Figure 1 - Types of Fronts. Fronts are boundaries between air masses of different temperatures. The type of front depends on both the direction in which the air mass is moving and the characteristics of the air mass. To locate a front on a surface map, look for the following: sharp temperature changes over relatively short distances, changes in the moisture content of the air dew point , shifts in wind direction, low pressure troughs and pressure changes, and clouds and precipitation patterns.

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. 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.

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