6.1-6.3

6.1 Pressure

  • hydrostatic pressure is the pressure in the ocean, weight of the water above an object pressing down due to gravity

  • pressure increases linearly with depth, increase of 1 atm per 10 meters increase in depth

  • at 1000 m, the pressure would be 101 (1 from the pressure at the surface)

  • Boyle’s law explains that 1) high pressure acts to compress air spaces such as lungs, so divers must have strong lungs and submarines must have strong hulls 2) at higher pressures, fluids have for dissolved gas, higher pressure water has more dissolved gases than surface water— the bends are when divers go down in depth too fast after breathing compressed air, the gases come out of solution and form bubbles in the blood that move towards joints

6.2 Temperature

  • the warmest waters are in the lower latitudes near the equator, and generally, the eastern side of oceans are colder than western side (because of surface currents)

  • warmer water remains at the top, getting rewarmed by the sun and refueling its energy

  • mixed layer: top 100-200 m deep water that stays the same relative temperature because surface winds, waves, and currents mix them together, beneath these layers, there is a greater decline in temperature (thermocline)

  • the bottom of the ocean has a very constant temp because there are little heat sources— its one of the most thermally stable regions of earth

  • tropical and polar regions have a lower thermocline while moderate latitudes have a higher thermocline because of the temp different from seasons

6.3 Density

  • mass/V

  • usual water density is 1g/cm³, but salts and ions add to 1.02-1.03

  • density is disproportional to temp, and proportional to salinity and P

  • thermocline circulation, movement of dense water down and less dense going to the surface

  • stratification prevents nutrient rich dense water from reaching the surface and keeping nutrients in lower depths, since tropical regions have warmer water and low density, they have lower productivity, polar regions are mainly cold at all depths, so nutrient water is allowed to mix around with the surface water giving it higher primary production