5 Weather Systems and Fronts Free Online FlashCards

What is an air mass?

A large body of air with relatively uniform temperature and moisture.

How do an air mass’s source region and surface shape its properties?

Air over land tends to be dry and air over water moist; air from high latitudes is generally cold, while tropical air is generally warm.

What does the air-mass code cP mean?

Continental polar: generally cold and dry.

How does a cold front typically lift air, and what weather may follow?

Advancing cold air pushes beneath warm air and lifts it steeply. A narrow band of showers or thunderstorms may form, often followed by cooler air.

What weather may develop ahead of a warm front?

Advancing warm air rises gradually over retreating cool air. Layered clouds and widespread, often steady precipitation may develop ahead of the surface boundary.

What characterizes a stationary front?

Neither air mass advances decisively, so clouds and precipitation can persist near the boundary, especially if it remains in place.

How does an occluded front form?

A faster-moving cold front catches up to a warm front, lifting the warm air away from the surface. Clouds and precipitation may occur around the boundary.

What do the standard weather-map symbols for fronts show?

Cold fronts use blue lines with triangles; warm fronts use red lines with semicircles; stationary fronts have alternating symbols pointing in opposite directions; occluded fronts use purple lines with alternating triangles and semicircles.

How do surface winds circulate around a low in each hemisphere?

Surface winds circulate counterclockwise around a low in the Northern Hemisphere and clockwise in the Southern Hemisphere.

Why can a surface low promote clouds and precipitation?

Air converges toward a surface low and rises. As it rises, it cools, which can promote cloud formation and precipitation.

How do extratropical and tropical cyclones differ?

An extratropical cyclone commonly develops along a boundary between contrasting air masses and is associated with warm and cold fronts. A tropical cyclone develops over warm tropical waters and is not organized around that typical front structure.

How does air move in an anticyclone, and how do its surface winds rotate?

Air generally sinks over the center and spreads outward near the surface. Surface winds circulate clockwise around a high in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.