Secondary Features of the Atmospheric Circulation

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Secondary Features of the Atmospheric Circulation

• Tropical Wave Cyclones
• Hurricane Description
• Hurricane Formation
• Hurricane Paths
• The Role of Hurricanes
• Chapters 8.3

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Tropical Wave Cyclones
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• These systems are known by many different names
• Hurricanes in the Caribbean and Gulf of Mexico
• Tropical cyclones in Australia
• Typhoons in the western Pacific and north Pacific
• Cyclones in the Bay of Bengal

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Hurricane Description
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• Hurricanes low pressure systems with winds over
  75 mph spiraling around a low pressure center (no
  fronts)
• The center is small, calm, and cloudless (the
  eye)
• Surrounding this eye is a series of cumulonimbus
  clouds through which air ascends in a spiral
  motion

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Hurricane Description
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Relates to Figure 8.20
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Hurricanes Description
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Hurricanes Description
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• Hurricanes are the most powerful and destructive
  of cyclonic storms

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Hurricane Description
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Not in Book
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Hurricane Description
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Hurricanes Formation
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• Late summer and early autumn
• Warmest temperatures
• Sea surface temperatures (SST) are at there
  highest
• SSTs greater than 27º C are needed
• Originate at latitudes between 7-15º
• Coriolis effect is too weak equator-ward of 7º
  SSTs too cool north of 15º

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Hurricane Paths
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• Hurricanes move in a westward or northwestward
  direction in the Northern Hemisphere when
  initially formed
• Once they move poleward of the subtropical highs,
  hurricanes start to move in a more eastward
  direction

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Hurricane Paths
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Relates to Figure 8.21
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Hurricane Paths
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Relates to Figure 8.21
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The Role of Hurricanes
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• They are extremely efficient in moving energy
  away from the tropical regions towards the poles
• As such, they play a profound role in maintaining
  the present climate system

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