Severe Weather

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Severe Weather
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Watch Vs. Warning

• Watch The conditions are right for severe
  weather.
• Stay tuned to reports
• Warning Severe weather has been sighted and it
  is advised to take cover.

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Thunderstorms

• Fast Facts
• Typically about 15 miles in Diameter
• Last 30 minutes
• Can occur at any moment around the world
• 16 Million Per Year
• Severe
• Hail a ¾ of inch

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How They Form

• Cumulonimbus clouds
• Caused by a cold front
• Also on hot, humid afternoons
• Three Key Ingredients
• War Humid Air (Fuel)
• Triggering mechanism
• What starts the storm
• Lifts moisture upwards so clouds can form and
  updrafts develop
• Instability
• Allows updrafts to accelerate up and down at high
  rates

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Lightening Thunder

• Areas of positive and negative electrical charges
  build up in the storm clouds
• Lighteningenergy discharge as the charges jump
  b/w parts of a cloud, nearby clouds, or clouds
  and the ground
• Can heat to as much as 30,000 degrees Celcius
• Hotter than the surface of the sun.

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Lightening Thunder Cont.

• Thunder, what causes it?
• The rapid heating of the air which expands
  suddenly and expands.
• Light Travels faster than sound.

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Tornadoes

• A rapidly, whirling, funnel-shaped cloud that
  reaches down from the storm cloud to touch the
  Earths surface
• Form along front
• Not all reach the Earth
• May touch for 15 minutes or less and be only a
  few 100 meters across
• Strength
• Wind speeds can reach 500km/hr
• Updraft in center is most powerful

• How they form
• Low, heavy cumulonimbus clouds.
• Spring and Early summer
• In the afternoon or early evening.
• Build up of heat in lower atmosphere
• Warm, Moist air mass from Gulf of Mexico
  (Maritime Tropical) meets with cold, dry mass
  from Canada (Continental Polar)

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Tornadoes Cont.

• Where are they located?
• Can occur anywhere, usually in spring and summer.
• Most in world occur in U.S.
• About 700-800 a year
• Tornado Alley
• Texas, Oklahoma, Kansas, Nebraska, Iowa
• Parts of Missouri, New Mexico, South Dakota

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