Heat

1
Heat Deep Ocean Currents
2
Heat VariationsLatitude

• Depends on angle sunlight hits surface

• Sunlight at polar latitudes covers wider area
  therefore, less heat

• At equator, sunlight covers less area more heat

• Mid latitude heating affected by seasons

3
Heat VariationsSeasons

• Earths axis tilted 23.5 - orbital inclination

• Northern hemisphere maximum solar energy in
  summer

• Southern hemisphere max. solar energy in our
  winter

4
Heat Budget

• Heat input Heat output

• 100 units 30 units 70 units

(heat Earth)
(Reflected)
(from sun)

• 70 units 47 units 23 units

(by atmosphere)
(absorbed by surface)
5
Annual Incoming Solar Radiation
Why dont oceans evaporate at equator and freeze
at poles?

• Surplus heat between 30 NS latitude

• Heat deficit between 30-90 NS latitude

6
Heat Transfer

• Heat is transferred from equator to poles

• Atmosphere

• Ocean currents

7
SalinityEvaporation and Precipitation

• Evaporation and precipitation control S

• Evaporation gt Precipitation ? S

• 0 (equator) and 40-60

• Precipitation gt Evaporation

• Lower S

• 10-40

• Evaporation gt Precipitation

• High S

• 60-90 (Polar Region)

• Freezing ? S

8
Ocean Salinities

• S variations lead to density stratification

• ? S ?density

• Denser H2O sinks

• Example of stratification (layering) is Atlantic
  Ocean

9
Atlantic Water MassesDensity Driven Currents

• Atlantic consists of intermediate, deep, and
  bottom waters

• Thickness and extent depends on

• Rate of formation

• Size of region where formed

10
Pacific Ocean

• Pacific Ocean not well defined

• Small region where water forms

• Limited H2O supply from north

11
Atlantic Water Flow

• Current driven by density contrast

• Dense, cold Polar H2O sinks

• Identify water masses by T-S curve and biology

12
AtlanticDeep Water Circulation

• Currents extensive and interconnected

13
Upwelling and Downwelling

• Wind blows H2O horizontally

• Deeper H2O rises to replace surface H2O

• Upwelling process of H2O rising

• Winds moving toward shore cause H2O to move
  downward

• Downwelling process of H2O sinking

14
Equatorial Upwelling

• Deep, nutrient-rich H2O is brought to the surface