WeatherSTEM Activity

Weather Fronts

A front is a transition zone between two air masses of different densities. Fronts bring changes in temperature, dew point, winds and pressure. They can also bring precipitation. Select each type of front below, then click-and-drag to see how it brings different weather conditions. To learn more about the type of front, click on the name.

Cold Front

Marked by lines of blue teeth on weather maps, cold fronts happen when cold air, denser and heavier than warm air, pushes against the warm air and slides underneath like a wedge. The warm air is forced upward and as it rises it cools, expands, and loses its ability to hold moisture, creating clouds and eventually precipitation and usually more intense thunderstorms.

Drag the cold air on the left towards the warm air to see how they interact.

Warm Front

A warm front, represented by red half circles on weather maps, happen when warm air moves in on cold air. Being less dense than cold air it rises above, like in a cold front. But in this case, it pushes the cold air downward against the earth and away. In the process it cools, expands, and loses its ability to hold moisture creating clouds and rain in the form of mild and spread out rainfall, as opposed to condensed thunderstorms.

Drag the warm air from the left to the right to see how the air masses interact.

Occluded Front

An occluded front, represented on weather maps by alternating purple half circles and triangles, happens when a cold front overtakes a warm front. One body of cold air approaches another, and the warm air is trapped in the middle. It is sandwiched by the two colder air masses and forced upwards, expanding and losing its moisture to create clouds and precipitation.

Drag the cold air in from the left to see how the air masses interact.

Stationary Front

A stationary front, represented on weather maps by an alternating cold and warm front line, happens when two air masses with equal force meet and sit stationary in place. Stationary fronts can stay in deadlock for an extended period, the warm air condensing into clouds and precipitation.