Chapter 20.3 HURRICANES

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Chapter 20.3 HURRICANES!
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Hurricanes

• Whirling tropical cyclones that produce winds of
  at least 119 km/hr.

• Occurrence of Hurricanes
• Most form between 5 and 20 degrees N and S
  latitude.
• The North Pacific has the greatest number of
  storms (avg 20/yr)

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Hurricane Katrina
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Development of Hurricanes

• They develop most often in the late summer when
  water temperatures are warm enough to provide the
  necessary heat and moisture to the air.

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Hurricane Anatomy

• Eye
• zone of scattered clouds
• Calm
• averaging about 20 kilometers in diameter at the
  center of a hurricane.
• Eye Wall
• doughnut-shaped area of intense cumulonimbus
  development
• very strong winds (surrounds the eye of a
  hurricane)

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Anatomy of a Hurricane
Satellite view from above.
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The Formation of a Hurricane

• Basic Stages
• Tropical Depression
• Winds near the center are constantly between 23
  - 39 mph
• Tropical Storm
• Winds between 39-73 mph
• Hurricane
• Winds at 74 mph

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The Steps in Hurricane Formation

• Warm air above the water rises and cools to form
  clouds.
• 2. More warm air comes in from all sides to
  replace the air that was rising. (This inward
  wind rotates because of the Coriolis Effect this
  is why hurricanes look like pin-wheels)

3. Hurricanes use energy from the warm ocean
water to grow stronger. As long as it has warm
water a hurricane will continue to grow.
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Hurricane Intensity

• The intensity of a hurricane is described using
  the Saffir-Simpson Scale.
• Storm surge - abnormal rise of the sea along a
  shore as a result of strong winds

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Different Terms for a Hurricane

• Hurricanes are called by different names in the
  different regions of the world
• In the Atlantic or Eastern Pacific Ocean
• They are called..."hurricanes"
• Western North Pacific and Philippines
• called "typhoons
• Indian and South Pacific Ocean
• They are called "cyclones"

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How Hurricanes are Named

• Hurricane History
• Short distinctive names are quicker and less
  subject to error than using latitude-longitude
• These advantages are especially important in
  exchanging detailed storm information between
  hundreds of widely scattered stations, coastal
  bases, and ships at sea.
• Since 1953, storms in the Atlantic have been
  named from lists originated by the National
  Hurricane Center. They are now maintained and
  updated by an international committee of the
  World Meteorological Organization.

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How Hurricanes are Named

• The original name lists featured only women's
  names.
• In 1979, men's names were introduced and they
  alternate with the women's names.
• The WMO uses six lists in rotation and the same
  lists are reused every six years. The only time a
  new name is added is if a hurricane is very
  deadly or costly. Then the name is retired and a
  new name is chosen. The 2005 list will be used
  again in 2011.

Retired Names
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Storm Names for 1994-1999
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Atlantic Names
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Hurricane Katrina

• It was the first Category 5 hurricane of the 2005
  Atlantic Hurricane Season
• It was the sixth-strongest Atlantic Hurricane
  ever recorded.
• The storm weakened to a Category 3 when it made
  landfall along the Central Gulf Coast on August
  29, 2005
• The storm surge from Katrina caused catastrophic
  damage along the coastlines
• Leeves in New Orleans were breached by the surge,
  ultimately flooding about 80 of the city.
• Wind damage was reported well inland, impeding
  relief efforts.
• Katrina is estimated to be responsible for 75
  billion in damages, making it the costliest
  hurricane in United States history
• The storm has killed 1,417 people, becoming the
  deadliest U.S. hurricane since the 1928
  Okeechobee Hurricane.

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The Path of Hurricane Katrina
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Hurricane Katrina
New Orleans
2005
ETUDE