Tropical air rising Warming air = lower density+increasing volume Rising air = lower pressure, lower temperature Condensation = warming Result: tremendous rainfall along the equator
Surface Ocean – Temp. is variable -2 to 30°C Deep ocean – Temp. is stable -1 to 4°C Average Temp. of the world ocean is 3.8°C 200 m
Sinking air Hadley Cell 0° Latitude Hot, humid 30° latitude Hot, dry (desert belt)
Surface ocean circulation Solar radiation Large heat capacity Heat variations lead to changes in pressures Air circulation (wind) –Gyres
Tropical Gyre Driven by wind –Trade winds –Westerly movement –Counter clockwise (CCW) direction (northern hemisphere)
Subtropical Gyre Very active evaporation –A product of warm/dry air moving over the oceans and land masses Results in a warm and salty Gulf Stream The gyre moves in a clockwise (CW) direction in this region.
Sub Polar Gyre Tremendous transfer of heat from the ocean to the atmosphere. –This warms the rising air that travels northeast and through northern Europe. –The Erbinger Current (Norwegian/Greenland Sea)
General surface current movements Winds mix and transport warm waters through the Earth’s oceans –Depth of 100 m –Average depth of 4000 m Warm water is circulated from the tropics towards the poles Coriolis force
Polar water/ice Ice is fresh water Circum-Antarctic Current: Flows around Antarctica –Circulates from west to east –4000 cubic meters of water –Insulates Antarctica (keeps it cold) This circulation pattern has a huge effect on global climate.
Deep Water Circulation Deep water goes from the North Atlantic to the North Pacific. Surface water flows opposite of the deep water pattern The deep cycle is about 800 to 1000 years. Surface water cycles occur on the order of decades.
Water and The Global Water Cycle Largest bulk chemical transfer on Earth Important to heat transfer from the Equator (evaporation) Patterns control regional distribution rainfall in terrestrial environments Movement of water is a function of evaporation and precipitation of two pumps. –Biologic –Physical
The Biological Pump Operates on feedback Nutrients + H20 +CO2 → organic matter + O2 Photosynthesis, CO2 Evapotranspiration O2 + H2O Nutrients, soil
Biologic Pump, negative feedback When there is ample water the inner cell is enlarged and promotes evapotranspiration When water is short the inner cell is closed allowing for the absence of evapotranspiration
Water budget Ocean (1,350,000) = 97% of the total water 425,000 385,000 40,000 Ice Ground water 8,200,000 27,500,000 Rivers, 40,000 Atmosphere = 13,000 Units - 1000 Km 3 : 1m water = metric tons, 50 * 1000 Km 3 = 10 18
Longer residence time for the land system Stock / flux – Residence time of water in the atmosphere –13,000 (atmosphere) / 425,000 (evaporation) = 0.3 years × 52 weeks Residence time in the oceans –1,350,000,000/425,000 = 3176 years
Calculate the residence time of land. Add the stocks and divide by the flux 357,040,000/425,000 = 840 years There are more stocks than listed here so the value of 840 years will be an underestimate.
Calculating the average evaporation and precipitation Ocean: –100 cm/yr, evaporation –70 cm/yr, precipitation Tropics –4mm/day (precipitation is skewed to the tropics because this zone account for 50% of the runoff on Earth Poles –X≤1mm/day, Desert belt 0% rain leads to little to no runoff.
The Jungle effect (Tropics) Trade winds The Amazon Basin Bio-enhanced cloud formation, This is a water trap set up by biologic activity Ocean Amazon River The Amazon and Oronoco flow systems are responsible for 20% of Earth’s runoff
Physical Pump Summer –Rainy season –Drives major rivers –Monsoons in India Winter –The ocean surface circulation follows wind patterns moving away from land