Earth's atmosphere drives global wind patterns through convection and the Coriolis effect. Warm air rises at the equator and sinks at the poles, creating convection cells that drive the trade winds and prevailing westerlies. The rotation of the Earth causes these winds to curve right in the northern hemisphere and left in the southern hemisphere. Local winds such as sea breezes and land breezes are also driven by differences in how land and water heat and cool.

1. Earth's Movement of Air Heat & Wind

2. Transfer of Heat Energy

3. Conduction Heat moving through molecules Molecules bumping into each other transfers heat gases are poor conductors metals are good conductors Animation

4. Convection Heat moves with the molecules as they flow - Warmer molecules move faster and push each other apart - Less dense particle masses rise up, leaving space - As molecules lose heat, they sink back down, creating a circular flow Gas and liquids only Animation

5. Radiation Does not involve matter (atoms) Can travel through space (vacuum) Electromagnetic waves carry heat Different wavelengths visible light infrared light ultraviolet light Sun, flame, light bulb or other heat source

8. Solar Radiation - Earth's Heat Source

9. Seasons Aphelion - Earth is farthest from the sun Perihelion - Earth is closest to the sun Solstices Summer solstice: longest Northern Hemisphere day Winter solstice: shortest Northern Hemisphere day Equinox Vernal & Autumnal Northern & Southern Hemisphere days are both 12 hours long

10. Atmospheric Convection Concentrated solar radiation at equator = hotter air (re-radiation) Rising heated air masses leave behind low pressure areas (L) Cold air from poles sinks down Denser (colder) air molecules results in high pressure areas (H) H L

11. Convection Cells Sinking polar air reaches warmer 60 o latitudes and rises Rising equatorial air reaches cooler 30 o latitudes and sinks In between (temperate latitudes)

13. Coriolis Effect The perceived curving of global winds due to Earth's rotation Marble Demo Video Illustration

14. Coriolis Effect Each cell curves (seemingly) Northern hemisphere curves right (clockwise) S. hemisphere curves left (counter-clockwise)

15. Speed of Rotation Polar matter rotates slower than equatorial matter Object lesson (student demo)

16. Global Winds Trade Winds North & South of the Equator Blow from East to West Prevailing Westerlies Latitudes 30 to 60 Named for the direction from which they blow Polar Easterlies North & South Poles Weak & irregular

18. Local Winds Smaller-scale convection Interact with global winds Influence by geography large bodies of water altitude (mountains, etc.)

20. Sea and Land Breezes Daytime : Land heats up faster than water Hot air over land rises (L) Cool air over water pushes onto land (H) Nighttime : Land cools faster than water Warm air over water rises (leaving a low pressure area) Cool air over land pushes into low pressure area over water Sea Breeze Land Breeze

21. Jet Streams High up in atmosphere Upper Troposphere Lower Stratosphere Form between cold & warm air masses bigger temperature difference = faster jet stream winds Flow west to east around the globe

23. Earth's Atmosphere Winds occur where? Troposphere & very lowest level Stratosphere What types of winds are there? Global Winds Trade Winds Prevailing Westerlies Polar Easterlies Local Winds Sea & Land Breezes Mountain & Valley Breezes Jet Streams Thermosphere Mesosphere Exosphere Troposphere Stratosphere