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Energy in the Atmosphere & Winds “The wind will blow, from high to low”
Three ways to transfer energy: • Radiation - electromagnetic energy (light). • Can travel in a vacuum. • Conduction - heat is transferred directly from molecule to molecule. • Ex. Pot handle gets too hot to handle. • Convection - energy is transferred through the movement of gases or liquids. • Usually due to uneven heating.
Winds • Basically, large scale convection currents with in the atmosphere.
Pressure and Heat • Why does warmer air generally mean lower pressure? Is the air rising or falling? • Why does colder air generally mean higher pressure? Is the air rising or falling?
Once again! “The wind will blow, From high to low”
If the Earth did not rotate: • Air rises at warmer equatorial areas. • Pressure is lower. • Air sinks at colder polar areas. • Pressure is higher. • Winds blow from polar highs to equatorial lows.
But, the Earth does rotate! • Thus, we must account for the Coriolis Force! • This turning of the winds divides them into wind belts. • Essentially a series of convection cells.
Global Wind Belts 1 • Trade Winds: located between 0° & 30°. • Air Rises at equator and sinks at 30° N & S. • Northeast and Southeast Trade winds. • At equator, a zone called the doldrums. • At 30° N and S called the “Horse Latitudes”
Global Wind Belts 2 • Westerlies: located between 30° & 60°. • Northern hemisphere - SW winds. • Southern hemisphere - NW winds. • Polar Easterlies: between 60° and the poles. • Air rises at 60° N & S and falls at poles.
Jet Streams • Bands of high-speed winds in both N and S hemispheres. • Found at 10 - 15 km, 100 km wide, 2-3 km thick. • Formed where polar and mid-latitude air come together. Great pressure differences create strong winds.
Aloha! The Ocean Breeze. . . • What causes ocean breezes during the day and land breezes during the night?
Home Work Read Chapter 24.1