1. Last time… Key questions 1.Why does air move? 2.Are movements of winds random across Earth’s surface, or do they follow regular patterns? 3.Implications of circulatory systems for global climate? 4.Other factors governing spatial distribution & seasonal patterns of temperature & precipitation?

2. Gas Laws Same “amount” of air But volume greater Density?

3. Relationships between Pressure, Temperature, and Volume P i * V i = P f * V f Boyles Law V i / T i = V f / T f Charles Law General Gas Law (P i * V i ) / T i = (P f * V f )/ T f

4. Global Energy Redistribution

5. North-South Circulation in the Troposphere

7. Implications of circulatory systems for global climate?

8. Water Vapor Warm air can hold move water vapor What happens when you cool air? Undersaturated Supersaturated

9. Global Precipitation Distribution

11. Water Balance Water in = rain Water out = evaporation

12. Deserts of the World 30˚ N and S H pressure side of Hadley Cells

13. Hydrologic Cycle What are the major reservoirs of water on the Earth? What are the components of the hydrologic cycle? Why does precipitation occur in some areas and not in others? What controls the seasonal cycle of precipitation?

14. The hydrologic cycle describes how water moves from one reservoir to another Often this movement is accompanied by a change of phase and the addition or release of stored energy

15. Water Cycle Atm. - Ocean - Land Evap. - PPT - Runoff

16. Distribution of Water Reservoirs Oceans 97% Atmosphere 0.01% Rivers, Lakes, and Inland Seas 0.141% Soil Moisture 0.0012% Ground Water 0.4 – 1.7% Ice Caps and Glaciers 1.725%

17. Water Cycle Atm. - Ocean - Land Evap. - PPT - Runoff

18. Change of Phase Evaporation/Melting/Sublimation –Addition of energy, change of phase Condensation/Freezing/Deposition –Release of energy, change of phase

19. Water is the ONLY naturally occurring substance that exists in all 3 phases (solid, liquid, gas) at temperatures found on the Earth’s surface Water, in all its phases, is the primary mechanism by which energy and matter are circulated among the Earth system components

20. Phase Changes of Water

21. Water Forms and Energy Converting water absorbs or releases energy If this happens in different places then energy is transferred

22. Global Water Balance 100 21 79 13 87 8 Anthes, p. 47 (modified) Earth’s annual water balance, (original) units are 10 5 km 3 of water per year. Huge quantities of water are cycled through the atmosphere each year. On the continents, precipitation exceeds evaporation and the reverse is true for oceans. Runoff from the continents balances the deficit of the oceans. Land Ocean Precipitation Runoff Total Water Evaporation

23. Transportation Precipitation Runoff Infiltration / Subsurface Flow Transport in air Transport in ocean currents

24. Why does it rain or snow?

25. Precipitation is caused by the uplift of moist air Air rising along the ITCZ or weather fronts (convergence) Convection caused by intense surface heating (not always accompanied by rain) Orographic uplift (rain deposited on windward side of mountains)

26. Relative Scales of Cloud-Forming Processes

27. Orographic Uplift

28. Water Vapor Warm air can hold move water vapor What happens when you cool air? Undersaturated Supersaturated

29. Global Circulation Where will rain fall?? High Pressure or Low Pressure

30. Northern Hemisphere Summer Precipitation ITCZ Shifts north SE Asia wet 30˚ N and S - Dry

31. Northern Hemisphere Winter Precipitation ITCZ Shifts south SE Asia dry 30˚ N and S - Dry