Physical Geography 101
Global Wind Patterns

Atmospheric Circulation

Scales of Motion: size and duration

Macroscale Winds:
Planetary-scale Winds:
Synoptic-scale Winds:

Mesoscale Winds:

Microscale Winds:

Ideal Global Wind Patterns

Start with an ideal globe model - no surface features, no seasons

Major Global Wind Belts

Intertropical Convergence Zone (ITC)

Trade Winds

Subtropical High Pressure Belt

Prevailing Westerlies

Polar Front

Polar Easterlies

Hadley Cell Circulation

Ferrel Cell Circulation

Polar Cell Circulation

Hadley-Ferrel-Polar Cell Circulation

Class Discussion of Actual Global Wind Patterns

January Global and Polar Wind Map

July Global and Polar Wind Map


Monsoons in Southern and Southeastern Asia: 3 factors.
1) Location and size of the Himalaya Mountains
2) Location of the Indian Ocean
3) extreme movement of the ITC in Asia - no similar shifts occur elsewhere in the world
- results in a reversal of wind direction between summer and winter.

In January, the wind direction is from the northeast, out of the Siberian High pressure center
- this is cold, very dry air.
This cold, dry air runs into the Himalayas.
What happens to it? Think in terms of orographic precipitation.

In July, the air mass is coming from the Indian Ocean, a southwest wind - this is very warm, very moist air.
This warm, moist air runs into the Himalayas. What happens to it?

Local Winds

1) Sea-Land breezes
2) Mountain winds - mountain barriers cause variable wind directions, updrafts and downdrafts are common
3) Drainage winds - cold air flows downward often following valleys
4) Chinook winds - warm, dry, leeward winds associated with the orographic precipitation process.