1 / 25

Class 15 -- The Oceans

Class 15 -- The Oceans. PROPERTIES OF SEA WATER Salinity Effect of salinity on physical properties ENERGY TRANSMISSION/ABSORPTION IN WATER AND SEA WATER Heat Light. SEA WATER (= Ocean water):. Salinity - - amt. of dissolved salts; symbol = S Average S = 35 g/kg (p.p.t., ‰)

zea
Download Presentation

Class 15 -- The Oceans

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Class 15 -- The Oceans PROPERTIES OF SEA WATER Salinity Effect of salinity on physical properties ENERGY TRANSMISSION/ABSORPTION IN WATER AND SEA WATER Heat Light

  2. SEA WATER (= Ocean water): • Salinity - - amt. of dissolved salts; symbol = S • Average S = 35 g/kg (p.p.t., ‰) • Range (most sea water): 30 -37 ‰ • How does sea water differ from fresh water? • Greater S --> greater density • Dissolved salts change water properties… • Boiling point higher = 103˚C • Freezing point lowered...

  3. Freezing of sea water: 1- salt exclusion • -- Begins to freeze at -2˚C • -- Salt is excluded from the ice that is formed. • -- Remaining water saltier, so... • -- This water freezes at lower temp. • -- As seawater cools below 4˚C, density increases • Very important: This means that the coldest sea water sinks to the bottom. • Oceans not stratified like lakes in winter

  4. Density of sea water just above • the freezing point • -- As seawater cools below 4˚C, density increases • Unlike fresh water lakes • Very important: This means that the coldest sea water sinks to the bottom. • This creates deep currents (more later)

  5. Density of seawater- • ... Higher S water is denser • ... Colder water is denser • Very important! Remember convection: • Dense water at ocean surface SINKS in places where water is • coldest and/or • salinity is highest, caused by • freezing • evaporation • “Deep water” currents come from these areas

  6. Why is the ocean blue? How deep does sunlight penetrate into the oceans? How does solar energy get absorbed by the ocean?

  7. Sunlight energy transmission and absorption by water • Radiant energy = Radiation -- direct transmission, through space, air, water, etc. • Different wavelength (l) waves are different colors of light, different types of radiant energy • Solar energy- many l’scombined

  8. Fig. 13.3

  9. Absorption of solar radiation by the oceans • Sun’s rays reaching the sea surface: • visible • infrared = heat • ultraviolet • Absorption by ocean water is strong, but depends on wavelength...

  10. How much energy or light is absorbed at various depths? What kind of energy or light is absorbed at various depths?

  11. Consequences: • Photosynthesis <150 meters • Heating from sun only affects top several meters • Blue color of sea water: only shorter wavelengths at depth

  12. Photosynthesis limited to top <150 m

  13. Water vapor = “latent” heat

  14. Heat Within The Oceans

  15. Conduction -- heat energy transfer between touching substances: warm to cool • Surface of the ocean <--> atmosphere • conduction important • BUT only affects the top few meters • Conduction between surface of ocean and deep water – not much • Water is a poor heat conductor over long distances • Example: Water at 1000m depth near Bahamas is barely above freezing!

  16. Warm Climate Zones: Warm surface layer+ cold water belowStratification

  17. Cooling Heating Convection Heat or “coldness” moves with density-driven currents Convection very important in the atmosphere and the oceans Atmosphere- Heated at bottom, cooled at top

  18. North Atlantic Equator Cooling Heating • Convection in the Oceans- • Cooling of surface water in far north, far south • Warming of surface water at low latitude

More Related