Objectives

1. List the scales of atmospheric motion categorized according to size and lifespan, and give examples of each.
2. Describe how sea and land breezes are produced.
3. Describe how mountain and valley breezes are produced.
4. Give examples of other local wind systems.
5. Describe the idealized pattern of global circulation as proposed by George Hadley.
6. Describe the idealized three-cell model of global circulation.
7. Describe a jet stream and discuss how the U.S. weather is influenced by the position of the jet stream.
8. Describe the relationship between the Southern Oscillation and a major El Nino event. Discuss how recent El Nino events have adversely affected U.S. weather.

Scales of Atmospheric Motion

• categorized according to average size and lifespan
• macroscale (planetary scale) - longwaves in the westerlies
• synoptic scale (weather map scale) - cyclones, anticyclones
• mesoscale - thunderstorms, tornadoes, land and sea breeze
• microscale - turbulence, wind gust

Local Wind Systems

• katabatic winds
• chinook winds
• Santa Ana winds
• dust devils
• Texas norther
• nor'easter

Sea Breeze

Land Breeze

Valley Breeze

Mountain Breeze

Global Circulation

• knowledge from observed pressure, wind and theory of fluid motion
• Hadley one cell model
• three cell model

Three Cell Model (a)

Three Cell Model (b)

Westerlies

• Global circulation in the middle latitudes
• Westerlies produce a general west to east movement of weather systems in the middle latitudes

Jet Stream

• narrow ribbons of high speed winds
• middle latitudes, 25,000 - 40,000 ft., 60 - 300 mi. wide, 120 - 240 mph

El Nino and the Southern Oscillation