Weather Hazards

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Weather Hazards

• Tornadoes
• Hurricanes
• Droughts
• Floods

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A Tornado
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Deadliest Tornado

• The Tri-State Tornado is the most violent
  tornado on record
• On March 18, 1925, the tornado formed in Missouri
  and traveled 219 miles across Illinois into
  Indiana
• The funnel was up to 0.75 miles across and
  traveled as fast as 73 mph
• It killed approximately 635 people

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What is a tornado?

• A violently rotating column of air (vortex)
  that touches the ground

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Tornado Oddities

• Tornados are reported to routinely carry objects
  many miles and have
• sucked the frogs out of a pond and dropped them
  on a town
• carried a necktie rack with 10 ties attached 40
  miles
• carried a flour sack 110 miles from a mill
• Tornados also drive objects into other objects
  and have
• driven splinters into an iron fire hydrant
• driven straw and grass into telephone poles

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Songer http//www.pitt.edu/super1/lecture/lec0761
/005.htm
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Where do tornados occur?

• Tornado Alley covers the Great Plains states

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Tornado Path

• View from the air of a tornado path in central
  Oklahoma

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Waterspouts

• A waterspout is a tornado that forms over a
  body of water, or a tornado that moves from land
  onto water

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Dust Devils

• A dust devil is also a vertical swirling column
  of air
• They rarely are as strong as even the weakest
  tornadoes

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Tornado Wind Speed

• In 1971, Dr. Fujita developed a way of
  measuring the winds of a tornado. He reasoned
  that there was a link between wind speed and the
  damage caused by a tornado. There are 6
  categories of tornados (F0 F5).

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F0 Category

• (Weak) winds 40-72 mph, little damage
• Damage tree branches snapped, chimneys toppled,
  signs torn down

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F3 Category

• (Strong) winds 158-206 mph, severe damage
• Damage most trees uprooted, trains overturned,
  roofs torn off, walls demolished

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F5 Category

• (Violent) winds 261- 319 mph, incredible damage,
  rare
• Damage bark peeled off trees, houses lifted off
  foundations, vehicles travel greater than 100
  yards through the air

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Tornado Occurrence by Category
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Tornado Deaths by Category
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Hurricanes
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Hurricane Katrina
An interdisciplinary, critical inquiry
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• Hurricane Katrina was the costliest and one of
  the deadliest hurricanes in the history of the
  United States
• It was the sixth strongest Atlantic hurricane
  ever recorded and the third strongest landfalling
  USA hurricane ever recorded

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Landfall

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What is a hurricane?

• A hurricane is an intense, rotating oceanic
  weather system that possesses maximum sustained
  winds exceeding 74 mph

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In other parts of the world, a hurricane is known
by other names

• typhoon
• - in the northeastern Pacific
• tropical cyclone
• - in the Indian Ocean and the eastern South
  Pacific

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How do they form?

• Hurricanes form and intensify over the ocean
• They require
• sea-surface temperatures of at least 80F
• the influence of the earths rotation to initiate
  a spinning circulation (Coriolis Effect)

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Most of these systems form between 10 and 30
degrees of the equator and 87 form within 20
degrees of it
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Storm Surge

• Definition a rise in sea level along a coastline
  caused by the combination of a hurricane's
  surface winds and the physical geography of a
  coastline

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Droughts

• Definition an extended period of below-normal
  
• rainfall
• Although what is considered "normal" varies from
  one region to another, drought is a recurring
  feature of nearly all the world's climatic
  regions

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Consequences from Drought Conditions

• Wildfires
• Desertification
• Loss of agricultural production
• Disease
• Thirst
• Famine due to lack of water for irrigation
• Social unrest
• Migration or relocation of those impacted
• War for water and foods

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The Dust Bowl

• The Dust Bowl was a series of dust storms in
  the central United States and Canada in the mid
  to late 1930s

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Causes of the Dust Bowl

• Massive drought
• Decades of inappropriate farming techniques

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Results of the Dust Bowl

• 15 of Oklahomas population migrated
• USA Government formed the Soil Conservation
  Service

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Floods

• A flood is an overflow of water duh?

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Causes of Flooding

• The main cause of floods is the location of human
  populations near water
• The worst floods usually occur when a river
  overflows its banks

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Preventing Flooding

• Rivers prone to flooding are often carefully
  managed
• Defenses such as levees, reservoirs, and weirs
  are used to prevent rivers from bursting their
  banks
• Coastal flooding has been addressed with sea
  walls and vegetation

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Levees
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Reservoirs
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Weirs
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Assignment
Create A Pamphlet
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Weather Hazards of the Earth

• Cover - must have title and must have some type
  of illustration
• 1st Section Hurricanes
• 2nd Section Tornadoes
• 3rd Section Floods and Drought
• These areas are to be addressed
• What is it?
• What are the effects?
• What can we do to prepare for it?
• There must be illustrations
• Back Cover - your name and the class period