Unit 5.4

Thunderstorms

small, intense weather systems producing strong winds, heavy rain, lightning, and thunder; 2 conditions necessary for development: warm, moist air new Earth's surface and unstable atmosphere; all surrounding air is colder than the rising air mass; the air

Cumulus

strong updrafts build the storm

Mature

heavy precipitation, cool downdrafts

Dissipating

warm updrafts disppear, light precipitation

Thunderstorm Formation

forms when rising warm air reaches its dew point, condensing and forming cumulus clouds; if the atmosphere is very unstable, the warm air will continue to rise; grow into a dark, cumulonimbuc cloud with a potential height of over 15 km.; in order for a th

Lightning

an electric discharge occurring between a positively charged area and a negatively charged area; when lightning strikes, energy is released and transferred to the air causing the air to expand and send out sound waves; can happen in 3 ways: cloud to cloud

Thunder

the sound resulting from teh rapid expansion of air along the lightning strike

Tornadoes

a destructive, rotating column of air having high wind speeds, low central pressure, and making contact with the ground; only happen in 1% of all thunderstorms; starts out as a funnel cloud poking through the bottom of a cumulonimbus cloud; the funnel clo

Tornado formation

wind moving in two directions causes a layer of air in the middle to begin to spin; the spinning column of air is turned to a vertical position by strong updrafts of air in the cumulonimbus cloud; the updrafts begin to spin as well; the spinning column of

Hurricanes

a large rotating tropical weather system having wind speed of at least 120 km/hr (75mph); they are the most powerful storms on Earth; can have different names: typhoons-- western Pacific ocean, and cyclones-- over Indian ocean; most form between 5 and 20

Thunderstorm safety

stay away from trees (possibility of lightning strikes); stay away from bodies of water

Tornado safety

find shelter in a basement or shelter; go to a windowless room in the center of a building

Hurricane safety

stay updated through your TV or radio station; evacuate if near shore and have disaster supply kit ready