The General Circulation

Anthes 5: 97-106

Global Pressure and Precipitation Zones

Jet Streams

Regional and Local Circulations

Anthes, Chapter 5, pp. 105-07 and 132-35

World’s Deserts and Dust Trajectories

Indian Summer Monsoon (wet)

Thermal low over Nepal.

Winds from sea.

Land slopes up.

Very wet.

425 in. of rain.

Latent heat release intensifies the circulation.

Indian Winter Monsoon (dry)

Cold, shallow High over Nepal.

Winds from land.

Air subsides from the highlands.

Climate fair and dry.

Pacific High (cold) vs. Bermuda High (warm)

Florida sea breeze convergence

Hawaii sea breezes from space

Lake Effect

Rain, Freezing Rain, Sleet, Snow

Air Masses and Fronts

Anthes, Chapter 5, pp. 107-113.

Air Masses

HOT COLD

WET mT mP

DRY cT cP

Air Mass Source Regions

Classic Norwegian Cyclone Model

Life Cycle of a Cyclone

Cold Fronts and Warm FrontsA Front is a transition zone between two air masses.

Stationary front -- no movement

Cold front

1. Sharp temperature change over short distance

2. Marked changes in the moisture (dew point)

3. Wind shift

4. Pressure change

5. Showery (convective) precipitation, then clearing

Warm front

1. Slower and more gradual transition than cold front

2. Lowering clouds (stratus) and steady precipitation

Cold Front (top), Warm Front (bottom)

Occluded Front

Upper Air Support: The Big Picture