FRONTS

What are Fronts? An interface (boundary) between 2 air masses. Where 2 different air masses meet. Conditions at the front are unstable and usually associated with precipitation

Types of Fronts: Page 13 in E.S.R.T. Icicles Half Suns

Cold Fronts: Cold air moves into an area occupied by warm air Warm air is already in place.

The colder, denser air pushes against and under the warm air The warm, less dense air rises, producing thick, tall clouds Wind speed increases, air pressure drops Precipitation occurs – moves quickly and violently

Temperatures are cooler behind a cold front, and warmer ahead of the cold front.

Cold Front Animation

Warm Fronts: Warm air mass moves into an area occupied by cool air

Warm air slides over the cold air.

The warmer, less dense air moves on top of cold air mass Warm air rises, expands, cools, and clouds form Air pressure falls, and precipitation follows Lasts for a longer period of time

Temperatures are warmer behind a warm front, and cooler ahead of the front.

Warm Front Animation

Warm Front Animation

Stationary Fronts: A cold air mass and a warm air mass collide, with no movement

Widespread rain will last for many days

Stationary Front Animation

A collision of air masses – warm and cold fronts meet

Occluded Front: Faster moving cold front overtakes a slower moving warm front

Warm front gets caught in between 2 cold fronts Widespread rain and thunderstorms Warm front gets caught in between 2 cold fronts Widespread rain and thunderstorms

Precipitation occurs right along the frontal boundary

Counter-clockwise What direction is this low pressure system rotating? On a weather map, fronts attach at a low pressure. Knowing this we can predict where each of the fronts will be next. What direction is this low pressure system rotating? Counter-clockwise

Front Questions Q: Towards what direction is the cold front moving? A: South East Q: Towards what direction is the warm front moving? A: North

Front Questions: Q: Is it colder in Los Angeles or El Paso? A: Los Angeles Q: Is it warmer in Memphis or New York? A: Memphis Q: What cities have high pressure? A: Houston, Seattle Q: What cities might be experiencing rain? A: El Paso, Memphis