TORNADOES Basic Description An extremely severe thunderstorm Size

TORNADOES

Basic Description � An extremely severe thunderstorm � Size: � Small funnel cloud � Several feet to a mile wide

Where/When they occur � Where: � Tornado Alley In the Great Plains of the US � When: � Spring and Early Summer � Late afternoon when the ground is warm � # per year: 800 in the US

How they are formed � Formation � Develop in cumulonimbus clouds (Thunderstorm clouds) � Warm humid air mass meets a cold dry air mass causing Thunderstorms � Only strong Thunderstorms cause tornadoes � Life Span � About 10 minutes

Speed � Travels at a speed of: 40 mph � Wind speed: up to 300 mph

Damage � � � � Strong winds Flying debris Rain, Hail Fujita Scale – categorized by damage, mph is only estimates based on damage � � � F 0 - < 73 mph; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged. F 1 - 73 -112 mph; mobile homes pushed off foundations or overturned; moving autos blown off roads. F 2 -113 -157 mph; Roofs torn off frame houses; mobile homes demolished; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground. F 3 -158 -206 mph ; Roofs torn off well-constructed houses; trains overturned; most trees in forest uprooted F 4 - 207 -260 mph ; Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown F 5 - 260 -318 mph; Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100

Predicting � Warnings/Watch � Watch: Tornadoes are possible � Warning: A tornado has been spotted � Predicted by: � Radar detects rotation of clouds � Tornadoes develop quickly, so very hard to predict � Symbol on a map