Predicting Weather

Large-Scale Weather Systems Front narrow region separating two air masses of different densities. Density differences are caused by differences in temperature, pressure, and humidity. Types of Fronts 1. Cold 2. Warm 3. Stationary 4. Occluded Stable Air Resistant to rising, fair weather

Two Types of Fronts 1. Warm Front

As the warm front moves in rain or snow begin they produce precipitation over large areas for an extended time

Warm Front Forms when warm air move into an area formerly covered by cooler air. On a map a warm front is shown with a red line with semicircles pointing toward the cooler air. extensive cloudiness and precipitation 1st sign of a warm front is cirrus clouds, followed by stratus and nimbus

2. cold front

COLD FRONT Forms when cold, dense air moves into a region occupied by warmer air On a map a cold front is shown with a blue line edged with blue triangles that point toward the warm air mass Towering clouds are a sign of a cold front produce showers, and thunderstorms

Associated with more violent weather Due to rate of movement and steepness of slope Forceful uplifting leads to heavy rain, down pours, and gusty winds

3. Stationary Front The front becomes parallel to the jet stream. moves very slow Show with blue triangles on one side and red semicircles on the other side Clouds and steady rain or snow for several days

4. Occluded Front When two cold fronts force out a warm front Weather is very complex and unpredictable Precipitation is common on both sides of an occluded front

Cyclones AntiCyclones Centers of low pressure that travel west to east Travel in a counterclockwise direction AntiCyclones Centers of high pressure Travel in a clockwise direction