Chapter 17 Sections 2 & 3 Pages 567-582 Thunderstorms Chapter 17 Sections 2 & 3 Pages 567-582

Thunderstorms Heavy rain storms and sometimes hail, accompanied by thunder and lightning. Form within large cumulonimbus clouds or thunderheads.

How Thunderstorms Form Form when warm air is forced upward at a cold front. Also formed on hot humid afternoons in the spring or summer. In both cases, warm humid air rises rapidly, as it rises it cools and forms a dense cumulonimbus cloud.

Lightning Positive and negative charges build up in the storm clouds. Lightning is the sudden spark, or energy discharge. May occur: cloud to cloud cloud to ground

Thunder Lightning heats the air around it to 30,000°C. The rapidly heated air expands suddenly and explosively. Thunder is the sound of the explosion. Thunder is heard after lightning because light travels faster than sound.

Thunderstorm Safety If outside: Avoid touching metal objects because they conduct electricity. Lightning usually strikes the tallest objects. Trees, house or flag poles.

Thunderstorm Safety If outside in an open area (golf course): Find an area low away from trees, fences and poles. Crouch down with your head down and hands on your knees. If swimming or on a boat, seek shelter away from the water.

Thunderstorm Safety If inside: Avoid touching phones, electrical appliances, or plumbing. They conduct electricity. Cars are safe they carry electricity around the metal skin, but do not touch metal in the car. Storm Menu