Air-Sea Interactions Convection currents, coriolis , and wind patterns

1. Air-Sea InteractionsConvection currents, coriolis, and wind patterns Fig. 6.11

2. Overview • Atmosphere and ocean one interdependent system • Solar energy creates winds • Winds drive surface ocean currents and waves • Examples of interactions: • El Niño • Currents

3. Seasons • Earth’s axis of rotation tilted with respect to ecliptic • Tilt responsible for seasons- will discuss later • Vernal (spring) equinox • Summer solstice • Autumnal equinox • Winter solstice • Seasonal changes and day/night cause unequal solar heating of Earth’s surface

4. Seasons Fig. 6-1

5. Movements in atmosphere • Air (wind) always moves from regions of high pressure to low • Cool dense air, higher surface pressure • Warm less dense air, lower surface pressure Fig. 6.6

6. Movements in air Non-rotating Earth • Air (wind) always moves from regions of high pressure to low • Convection or circulation cell Fig. 6.7

7. Physical properties of atmosphere • Warm air, less dense (rises) • Cool air, more dense (sinks) • Moist air, less dense (rises) • Dry air, more dense (sinks) Fig. 6.5

8. Low & High Pressure Systems • Winds: H L Air movement

9. Low & High Pressure Systems Winds: Air movement H L

10. Low & High Pressure Systems Winds: Air movement H L

11. Low & High Pressure Systems Winds: Air movement H L

12. Low & High Pressure Systems Low and high pressure areas “chase” each other around H L Air movement

13. Air movement Air Movement • What happens to warm air as it rises? • Temperature: • Precipitation: • Density: • Movement:

14. Air movement Air Movement • Warm air rises • Heat makes molecules move more • Further-apart molecules = lower density • Less dense air rises above more dense air • Cold air sinks • Colder molecules move less • Become packed more closely together • Denser cool air sinks below less dense air

15. If this is true, how come the earths wind patterns don’t look like this?

16. Movements in air on a rotating Earth • Coriolis effect causes deflection in moving body • Due to Earth’s rotation to east • Most pronounced on objects that move long distances across latitudes • Deflection to right in Northern Hemisphere • Deflection to left in Southern Hemisphere • Maximum Coriolis effect at poles • No Coriolis effect at equator

17. Coriolis Effect

18. Coriolis Effect The Coriolis Effect • In the Northern Hemisphere: • Objects are deflected to the right • Faster-moving objects are deflected more • Deflection is stronger closer to the poles • In the Southern Hemisphere: • Objects are deflected to the left • Faster-moving objects are deflected more • Deflection is stronger closer to the poles

19. N W E S Coriolis Effect Northern Hemisphere Deflection Equator

20. N W E S Coriolis Effect Northern Hemisphere Deflection Equator

21. N W E S Coriolis Effect Northern Hemisphere Deflection Equator

22. N W E S Coriolis Effect Northern Hemisphere Deflection Equator

23. N W E S Coriolis Effect Northern Hemisphere Deflection Equator

24. N W E S Coriolis Effect Northern Hemisphere Deflection Equator

25. N W E S Coriolis Effect Northern Hemisphere Deflection Equator

26. N W E S Coriolis Effect Southern Hemisphere Deflection Equator

27. N W E S Coriolis Effect Southern Hemisphere Deflection Equator

28. Coriolis Effect Examples: • A plane leaves Myrtle Beach for Montreal, but does not correct for the Coriolis Effect. Where does it wind up in relation to its intended destination? • A plane leaves Myrtle Beach for San Diego, but does not correct for the Coriolis Effect. Where does it wind up in relation to its intended destination?

29. Coriolis Effect Montreal San Diego Aerial Image: NASA

30. Coriolis Effect Montreal San Diego Coriolis Effect Not To Scale Aerial Image: NASA

31. Coriolis Effect Montreal San Diego Coriolis Effect Not To Scale Aerial Image: NASA

32. Due to coriolis , unequal solar heating, and convection, air patterns actually look like this Fig. 6.10

33. Global Wind Patterns

35. Global atmospheric circulation • Circulation cells circulate as air changes density due to: • Changes in air temperature • Changes in water vapor content • Circulation cells • Hadley cells (0o to 30o N and S) • Ferrel cells (30o to 60o N and S) • Polar cells (60o to 90o N and S)

36. Global atmospheric circulation • High pressure zones • Subtropical highs • Polar highs • Clear skies • Low pressure zones • Equatorial low • Subpolar lows • Overcast skies with lots of precipitation

41. Fig. 6.10

42. Global wind belts • Trade winds • Northeast trades in Northern Hemisphere • Southeast trades in Southern Hemisphere • Prevailing westerlies • Polar easterlies • Boundaries between wind belts • Doldrums or Intertropical Convergence Zone (ITCZ) • Horse latitudes • Polar fronts

43. Atmospheric Summary • Pressures • -- lows • -- highs • Circulationcells: • -- Hadley (equatorial) • -- Ferrel (mid-latitude) • -- Polar • Winds: • -- NE trade winds • -- SE trade winds • -- Prevailing westerlies • -- Polar easterlies • Boundaries: • -- Doldrums (ITCZ) • -- Horse latitudes • -- Polar front Atmospheric Circulation

44. Coastal winds • Solar heating • Different heat capacities of land and water • Sea breeze • From ocean to land • Land breeze • From land to ocean Fig. 6.13