Weather Patterns and Severe Storms Chapter 20 Air Mass - large body of air with a consistent temperature and moisture. - as it moves, it changes the weather and may change itself.

* U.S. affected most by cP and mT* Air Mass Types 1) Continental Tropical (cT) - warm, dry air from the land 2) Continental Polar (cP) - cold, dry air from the land 3) Maritime Tropical (mT) - warm, moist air from the ocean 4) Maritime Polar (mP) - cold, moist air from the ocean * U.S. affected most by cP and mT*

Air Masses Are Classified by Region

Fronts - boundary separating 2 air masses Types 1) Warm Front - warm air moves into area with cold air in place.

2) Cold Front - cold air moves into area with warm air in place.

3) Stationary Front - warm & cold air move side by side (not against each other)

4) Occluded Front - cold front that takes over a warm front

Severe Weather Thunderstorms 1) Formation - warm, moist air rises into unstable air - develops in low, cumulus clouds 2) Characteristics - lightning, thunder, heavy rain, wind, hail

Tornados 1) Formation a) air rotates(rolls) horizontally within a thunderstorm b) rolling air (vortex) rises up vertically c) once vertical, tornado is formed 2) Characteristics - extremely low pressure inside - air is sucked in, towards a tornado - winds between 60-250 mph.

Formation of a Tornado

Hurricanes 1) Formation a) thunderstorms gather over warm ocean water b) strong, low pressure system builds c) If ocean water is warm enough: - low pressure becomes a hurricane 2) Characteristics - very low pressure inside - winds 74 mph or greater

Hurricanes consist of: 1) Eye - calm center of storm 2) Eye Wall - strongest storms around eye 3) Rain Bands - rain clouds drawn into center 4) Storm Surge - ocean water pushed ahead by the storm

Cross Section of a Hurricane

Satellite View of Hurricane Floyd