Thermal CirculationThermal Circulation
ByBy
Dr. Robert M MacKayDr. Robert M MacKay
Clark College Physics & Clark College Physics & MeteorologyMeteorology
A tale of two identical A tale of two identical citiescities
The air above City 1 cools and that The air above City 1 cools and that above City 2 warmsabove City 2 warms
Air pressure aloft is High above City Air pressure aloft is High above City 22
Winds aloft blow from city 2 to city Winds aloft blow from city 2 to city 1.1.
Examples of Thermal Examples of Thermal CirculationsCirculations
Sea Breeze during the day
Land Breeze at night
South East Asian MonsoonVery dry
South East Asian Monsoon
Very wet
Mountain or Valley breeze??
Upward motion of Valley breeze made visible by clouds
Sea breeze convergence zone in Florida giving rise to very frequent thunderstorms. Florida has more thunderstorms each year than anywhere else in the US.
Stepped Art
Fig. 9-25, p. 241
Local WindsLocal Winds
• Santa Anna WindsSanta Anna Winds– Warm dry that blows from east or Warm dry that blows from east or
northeast don canyons into S. Californianortheast don canyons into S. California– Very fast, desiccates vegetation, Very fast, desiccates vegetation,
providing fuel for firesproviding fuel for fires
• Desert windsDesert winds– Dust storms, sand storms, dust devil, Dust storms, sand storms, dust devil,
haboobhaboob
