Storms

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Storms
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Storms

• A storm is a violent disturbance in the
  atmosphere
• 4 major types of storms
• Thunderstorms
• Tornadoes
• Hurricanes
• Winter Storms
• A meteorologist is a scientist who studies
  weather and tries to predict it

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Thunderstorms

• A thunderstorm is a small storm often accompanied
  by heavy precipitation and frequent thunder and
  lightning.
• Form in large cumulonimbus clouds (also called
  thunderheads) on hot, humid afternoons

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Thunderstorms

• Warm, humid air rises rapidly and the air cools,
  forming dense thunderhead clouds
• Heavy rain falls, sometimes along with hail
• Within the thunderhead cloud there are strong
  updrafts and downdrafts

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Lightning

• Lightning is a sudden spark, or electrical
  discharge
• Positive and negative charges jump between parts
  of a cloud, or between nearby clouds, or between
  a cloud and the ground

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Thunderstorms

• Lightning heats the air to 30,000oC
• Thunder is the sound of the rapidly heated air
  expanding suddenly and explosively
• Light travels faster than sound so you see
  lightning before you hear thunder

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Calculating Lightning Distances

• Watch the sky for a flash of lightning.
• Count the number of seconds until you hear
  thunder.
• Divide the number of seconds by 5 to calculate
  the distance the storm is away from your location
  in miles (or divide by 3 for kilometers).
• Ex If you counted 18 seconds from when you saw
  the lightning, the strike was 3.6 miles (6
  kilometers) from your location.

Divide Number of Seconds by 3 for Distance in
Kmor 5 for Distance in Miles.
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Examples of types of Lightning

• Spider-Flashes of spider lightning crawl across
  the sky for up to 90 miles.
• Sheet lightning - Normal lightning that is
  reflected in the clouds
• Heat lightning - Normal lightning near the
  horizon that is reflected by high clouds
• Ball lightning - A phenomenon where lightning
  forms a slow, moving ball that can burn objects
  in its path before exploding or burning out
• Red sprite - A red burst reported to occur above
  storm clouds and reaching a few miles in length
  (toward the stratosphere)
• Blue jet - A blue, cone-shaped burst that occurs
  above the center of a storm cloud and moves
  upward (toward the stratosphere) at a high rate
  of speed
• Ribbon lightning-Ribbon lightning occurs in
  thunderstorms with high cross winds and multiple
  return strokes. The wind will blow each
  successive return stroke slightly to one side of
  the previous return stroke, causing a ribbon
  effect.
• Bead lightning- Bead lightning is a type of
  cloud-to-ground lightning which appears to break
  up into a string of short, bright sections, which
  last longer than the usual discharge channel. It
  is fairly rare.
• Forked lightning-Forked lightning occurs when a
  second lightning stroke doesn't follow the same
  path as the first lightning stroke. Thus, it
  appears forked.

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Lightning Strikes in the U.S.

• This map shows how often lightning strikes
  different parts of the lower 48 states. Central
  Florida has the most intense concentration of
  cloud-to-ground lightning because it has a lot of
  warm, humid air. The Pacific Northwest has almost
  no lightning.

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Thunderstorm Safety

• Go INSIDE!
• Do NOT touch anything that can conduct
  electricity-especially metal objects and bodies
  of water
• Crouch down in a low area-avoid trees

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Tornadoes

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

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Tornado Formation

• Warm, moist air flows in at the bottom of a
  cumulonimbus cloud and moves upward
• A low pressure area forms inside the cloud
• Warm air rotates as it meets winds blowing in
  different directions at different altitudes

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• Tornado Alley is an area of the United States
  that has a high frequency of tornadoes because
  cold, dry air moves south from Canada to meet
  warm, humid air from the Gulf of Mexico
• 5 states that cross Tornado Alley are
• Texas
• Oklahoma
• Kansas
• Nebraska
• Iowa

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The Fujita Tornado Damage Scale

• Tornadoes are ranked on the Fujita scale by the
  amount of damage they cause

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Tornado Safety

• A tornado watch is an announcement that tornadoes
  are possible in your area. Stay tuned to the
  radio or television news.
• A tornado warning is an announcement that a
  tornado has been sighted. Take shelter
  immediately!
• The safest place to be during a tornado is in a
  storm shelter or the basement of a well-built
  building

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Hurricanes

• A hurricane is a tropical cyclone that has winds
  of 119 km/h or higher
• Hurricanes form in the Atlantic, Pacific, and
  Indian Oceans
• In the western Pacific Ocean, hurricanes are
  called typhoons
• A hurricane begins over warm ocean water as a
  low-pressure area, or tropical disturbance.
• A hurricane draws its energy from the warm, humid
  air at the oceans surface
• As the air rises and forms clouds, more air is
  drawn into the system
• Inside the storm are bands of very high winds and
  heavy rains
• Winds spiral inward toward the area of lowest
  pressure at the center

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Hurricane Names

• Hurricanes are given names to help us identify
  them and track them as they move across the ocean
• Men and women's names are used
• One name for each letter of the alphabet except
  Q, U, and Z
• World Meteorological Organization uses six lists
  in rotation
• The only time a new name is added is if a
  hurricane is very deadly or costly
• If that happens then the name is retired and a
  new name is chosen.

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2008 2009 2010 2011 2012 2013
ArthurBerthaCristobalDollyEdouardFayGustavHannaIkeJosephineKyleLauraMarcoNanaOmarPalomaReneSallyTeddyVickyWilfred AnaBillClaudetteDannyErikaFredGraceHenriIdaJoaquinKateLarryMindyNicholasOdettePeterRoseSamTeresaVictorWanda AlexBonnieColinDanielleEarlFionaGastonHermineIgorJuliaKarlLisaMatthewNicoleOttoPaulaRichardSharyTomasVirginieWalter ArleneBretCindyDonEmilyFranklinGertHarveyIreneJoseKatiaLeeMariaNateOpheliaPhilippeRinaSeanTammyVinceWhitney AlbertoBerylChrisDebbyErnestoFlorenceGordonHeleneIsaacJoyceKirkLeslieMichaelNadineOscarPattyRafaelSandyTonyValerieWilliam AndreaBarryChantalDorianErinFernandGabrielleHumbertoIngridJerryKarenLorenzoMelissaNestorOlgaPabloRebekahSebastienTanyaVanWendy
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Hurricane Formation
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Hurricanes

• Hurricanes last longer than other storms, usually
  a week or more
• After a hurricane passes over land, it no longer
  has warm, moist air to draw energy from so it
  loses strength
• A storm surge is a dome of water that sweeps
  across the coast where a hurricane lands
• For safety during a hurricane, people are told to
  evacuate
• Evacuate means to leave the area immediately

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Winter Storms

• All year round, most precipitation begins in
  clouds as snow
• A large amount of humid air that cools below 0oC
  can produce a winter storm
• Lake Effect Snow-areas east of the Great Lakes
  get a LOT of snow WHY?

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Lake-Effect Snow

• The land cools much more rapidly than the water
  in the Great Lakes (or any lake)
• When a cold, dry air mass from central Canada
  moves southeast across one of the Great Lakes, it
  picks up water vapor and heat from the lake
• As soon as the air mass reaches the other side of
  the lake, the air rises and cools again
• The water vapor condenses and falls as snow
• Cities such as Buffalo and Rochester, New York
  are two of the snowiest cities in the U.S.
  because they are located east of the Great Lakes

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Lake Effect Snow
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