Tuesday, Feb. 19, 2013 ***MAKE SURE YOU ARE IN DRESS CODE*** Be in your seat when the bell rings! Complete Bell Ringer (below) Explain which air masses influence weather patterns in N. America. What do you think will happen when two air masses meet? Be prepared to start notes

Bell Ringer Explain which air masses influence weather patterns in N. America. ( mT and cP) What do you think will happen when two air masses meet? (fronts will form)

Fronts When two air masses meet boundary separating the two air masses.

Warm Front A warm front – warm air moves into an area formerly covered by cooler air Warm air glides up over a cold, dense air mass Weather Conditions: Light to moderate rain Video

Warm Front

Cold Front Animation Cold air mass moves into an area occupied by warmer air. Weather Conditions: Thunderstorms Video

Cold Front

Stationary front Created when cold and warm masses meet but neither one has enough force to move the other out of the way. The water vapor in the warm air condenses into rain, fog, snow, clouds. Can bring many days of precipitation

Occluded front Is created when a warm air mass is caught between two cooler air masses. The two denser cooler air masses cut off the warm air mass from the ground. As the warm air mass cools, it may turn cloudy, rainy or snowy.

Occluded Front