Force of air on a given surface divided by the area of that surface. Plays a vital role in weather systems. High-pressure areas have higher pressure than surroundings, low-pressure areas have lower pressure. Most storms occur in low-pressure areas.
Boundary between two air masses of different densities, moisture, or temperature. Can be classified as cold, warm, occluded, or stationary. Storms, precipitation, and cloudiness sometimes occur at frontal boundaries.
Boundary along a warm air mass pushing out a cold air mass. Brings high cirrus clouds, followed by stratus and nimbus clouds, and steady rain. Temperature rises as warm air replaces cold air.
Boundary along a cold air mass pushing out a warm air mass. Lifts warm air, causing water vapor to condense and form cumulonimbus clouds that can bring thunderstorms, rain showers, or tornadoes. Sky becomes clear as cold front passes.
Formed when two cold air masses move toward each other with warm air between them. Colder air pushes warm air upward, closing it off from the surface. Brings steady rain.