WEATHER PATTERNS Chapter 15.2 Pages

Air Masses A large body of air with similar properties such as temperature and humidity. They are similar to the surface over which they develop. Warm temperature (tropical areas) Cold temperature (polar areas) High humidity (maritime) Low humidity (continental)

Pressure Systems High pressure are areas where air is moving towards the earth. Low pressure are areas where air is moving away from the earth. High pressure usually means good weather. Low pressure usually means cloudy weather.

Weather Fronts The boundaries between two different air masses Storms and precipitation occur at fronts Four different types of fronts

Warm Front Warm air slides over cold air. Precipitation occurs over a wide area.

Cold Front Cold air pushes under warm air Narrow band of violent storms

Occluded Front 2 cold air masses merge and force the warm air between them to rise. Strong winds and heavy precipitation may occur.

Stationary Front Air pressure causes either a warm or cold front to stop moving. Light winds and precipitation across the entire frontal region are common.