Monsoons

1
Monsoons

• Definition
• Location of Monsoon Climates
• Focus on the Indian Monsoon
• Chapter 8.2

2
Monsoons
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• Definition
• A seasonal reversal of wind, which in the summer
  season blows onshore, bringing with it heavy
  rains, and in the winter season blows offshore
• At least a 120º change in wind direction
• Derived from the Arabic word mausin, meaning a
  season

3
Monsoons
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• A distinct rainy season (summer) and a distinct
  dry season (winter)
• Wet monsoon (high sun)
• Dry monsoon (low sun)

4
Location of Monsoon Climates
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Not in Book
5
MonsoonsWinter shift in the ITCZ
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Not in Book
6
MonsoonsSummer shift in the ITCZ
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Not in Book
7
The West African Monsoon
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Not in Book
8
The Australian Monsoon
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Not in Book
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The East Asian Monsoon
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Not in Book
10
The Indian Monsoon
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Not in Book
11
Focus on the Indian Monsoon
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• Complex process involving a number of factors
• Seasonal shift of the ITCZ
• Seasonal surface pressure changes
• Jet streams aloft

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Indian Winter MonsoonStructure of the
Atmospheric Circulation
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Not in Book
13
Indian Winter MonsoonSurface Pressure
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Not in Book
14
Indian Winter MonsoonJet Streams Aloft
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Convergence Aloft
Figure 8.15
15
Indian Winter Monsoon
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• ITCZ in Southern Hemisphere
• High pressure over Asia
• Westerly Subtropical Jet
• Winds blow offshore
• Dry monsoon

16
Indian Summer MonsoonStructure of the
Atmospheric Circulation
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Not in Book
17
Indian Summer MonsoonSurface Pressure
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Not in Book
18
Indian Summer MonsoonJet Streams Aloft
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Divergence Aloft
Figure 8.15
19
Indian Summer Monsoon
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• ITCZ over Asia
• Low pressure over Asia
• Easterly Tropical Jet
• Winds blow onshore
• Wet monsoon
• Precipitation amount is enhanced by orographic
  uplift

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Indian Summer Monsoon
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Figure 8.17
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