Severe Weather

The Water Cycle is the driving force behind all severe weather Thunderstorms Large storms with strong winds, thunder and lightning. These are produced by cumulonimbus clouds. Lightning Areas of positive and negative electrical charges build up in a cloud A sudden energy discharge between two areas Can happen from cloud to ground, cloud to cloud or ground to cloud

Thunder This happens when lightning occurs Lightning heats the air to 35,000 degrees Fahrenheit This causes the air to expand rapidly, causing a “sonic boom”

Tornadoes These are produced by cumulonimbus clouds Usually occur when a warm, humid air mass collides with a cool, dry air mass (cold front) Hypothesis - Horizontal spinning turns vertical.

http://www.msnbc.msn.com/id/9007188/ns/w eather-weather_news/t/birth-tornado/

Hurricanes Hurricanes begin as a tropical depression Low pressure area (over warm tropical waters) As it grows in size it becomes a tropical storm If it increases in size and strength it becomes a hurricane Once the winds reach 75 mph it becomes a hurricane Hurricanes get their energy from the warm, humid air at the water’s surface rising and condensing

What causes hurricanes to move westerly toward the US East Coast? TRADE WINDS What direction do hurricanes rotate? COUN TERCLOCKWISE What are natural ways hurricanes are altered (buffered)? BARRIER ISLANDS AND WETLANDS