Ocean Physics. Ocean Physics. Buoyancy Temperature Light Density Pressure Depth Salinity Sound Dissolved Gasses. Buoyancy. Archimedes Principle of Buoyancy A floating object displaces a volume of fluid equal in mass to the floating object. empty. loaded with fish. Displaced water.
A floating object displaces a volume of fluid equal in mass to the floating object
loaded with fish
Lines of equal temperature
Feb 4, 2014
Only green and blue wavelengths pass through water a great distance.
~65% of visible light is absorbed in the 1st m
Refraction- as light enters the water, it bends; this is due to light traveling through different densities
Light entering the ocean is weakened by scattering and absorption.
Air is compressible
Water is incompressible
Water doesn’t change density under pressure
Low High Low High Low High
Thermocline + Halocline = Pycnocline
Speed of sound- faster in ocean (higher density)
1500 m/sec, which is 4x faster than in air
Difficult to determine direction of sound
Can hear many things such as ships miles away, shrimp eating, helicopters overhead, and whales communicating.
source of noise
Solubility of Gases in Seawater as a Function of Temperature (salinity @ 33o/oo)
(ml/l at atmospheric pressure)
Temperature N2 O2 CO2
0 14.47 8.14 8,700
10 11.59 6.42 8,030
20 9.65 5.26 7,350
30 8.26 4.41 6,660
Air weighs 14 lbs/in2 (psi)
Absolute pressure is the combined pressure of water and air
1 atm 14.7 psi
2 atm 29.4 psi
3 atm 44.1 psi
4 atm 58.8 psi
For any gas at a constant temperature, the volume will vary inversely with absolute pressure while the density will vary with absolute pressure.
I.e., volume with pressure
The total pressure of a gas exerted by a mixture of gas is the sum of the gases exerted independently.
Air % partial pressure (mm Hg)
N2 78.6 597
O2 21.0 159
CO2 0.04 0.3
H2O 0.46 3.7
Total 100 760
Partial pressure is directly related to its % in the total gas mixture. E.g., at 1 atm PO2 = 159 mm Hg
When a mixture of gas is in contact w/a liquid, each gas will dissolve in the liquid in proportion to its partial pressure.
Gasses can go in and out of solution
e.g., open soda, get CO2 bubbles (CO2 is under pressure)
Increase pressure, increase concentration
N2 48% 78%
O2 36% 21%
CO2 15% 0.04%
Honaunau Tide Pool
Gasses dissolve most readily in cold water