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Text Book : Pages 450 - 459

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A violent disturbance in the atmosphere.

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Involves sudden changes in air pressure Cause rapid air movement Conditions that bring one kind of storm in one area often cause other kinds of storms in the same area

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Thunderstorms Tornadoes Snowstorms Hurricanes

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Torrential Downpours Strong winds at greater than 58 mph Hail inch diameter (or larger) Frequent lightning

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Issued by National Weather Service This means that conditions are favorable for a thunderstorm Length is multiple hours.

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Issued By Local Weather Service Means a severe storm has been spotted by doppler radar Usually only an hour

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A sudden spark or energy discharge, caused when electric discharges jump between parts of a cloud, nearby clouds, or between a cloud and the ground.

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Temperatures of over 30,000 C (much hotter than Suns surface) Heated air expands suddenly and explosively making a sound of thunder.

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Because light travels much faster than sound.

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Stay indoors, away from doors and windows. Avoid objects that conducts electricity, such as metal objects and bodies of water. Do not seek shelter under the trees. Do not use phones with cords. Remember: Cars are pretty safe

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Tornado Alley

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A tornado is a rapidly whirling, funnel shaped cloud that reaches down from a cloud to touch Earths surface.

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Same system that produces thunderstorms can produce tornadoes. Late in the day, when earths surface is very warm, convection (the flow of heat through a material, causing hot parts to rise and cooler parts to sink) can get very strong. This can lead to a tornado.

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Conditions are favorable for a tornado to form A tornado has formed.

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Tornado Happenings 1. When the updraft in a convection cell is really strong, the air rushes in from all sides at high speeds.

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2. Air curves into a spin. This lowers the pressure even more. Air rushes in even faster, and the pressure gets even lower, and so on. LLike a skater who pulls her arms in close to her sides. The tornado spins faster and faster.

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3. As the tornado gets stronger, a funnel forms that can destroy anything in its path. The center of the tornado can reach speeds of 500 kilometers per hour (about 300 miles per hour) or more.

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Where Do Tornadoes Happen? Tornadoes happen where dry, cold air masses mix with warm, moist air masses. More tornadoes occur in the United States than in any other country, especially in the area known as TORNADO ALLEY.

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A Famous Tornado Grand Island, Nebraska June 3, 1980

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On June 3, 1980, a series of tornadoes devastated the city of Grand Island, Nebraska. Seven tornadoes hit within a three hour period. The storm did massive damage and closed the city down for three days.

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About 800 tornadoes every year in the United States. The safest place to take a shelter in a storm shelter or the basement of a well- built building.

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All year round, most precipitation begins in clouds as snow. If the air is colder than 0 degrees all the way to the ground, the precipitation falls as snow.

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Try to find a shelter from the wind. Cover exposed parts of your body and try to stay dry.

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A tropical storm that has winds of about 119 kilometers per hour or higher (200 miles per hour). Storm usually doesnt last for more than 7-10 days. As it moves inland it continues to move across the land but it begins to weaken

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Map Symbols

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Intertropical Convergence Zone The ITCZ is an area of low pressure located roughly 5 degrees North and South of the Equator. It is a place where air converges, rises, and condenses (forming clouds). It is the rainiest place on Earth!

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So What Does a Hurricane Need in Order to Develop? So a hurricane needs warm water, time to grow, and favorable upper level winds in the troposphere. If the winds are too strong, they will blow the hurricane apart we call that wind shear!

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A list of names from A-W (excluding Q) Alternate from male to female 6 lists, repeated in cycle Big name storms replaced

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A hurricane poses a possible threat within the next 36 hours Hurricane conditions expected within 24 hours

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The Saffir-Simpson Scale http://www.nhc.noaa.gov/aboutsshws.phphttp://www.nhc.noaa.gov/aboutsshws.php Saffir-Simpson Wind Scale and Animations http://www.nhc.noaa.gov/surge/ http://www.nhc.noaa.gov/surge/ Storm Surge Overview and Animations

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Best plan is to evacuate Towns have voluntary evacuation during a watch, and some switch to mandatory during a warning. Plan early in advance

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Board all windows Prepare Flashlights, avoid candles Stay tuned to radio Stay indoors

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