Wind - Keynote pdf
Currents - Keynote pdf
Seawater Chemistry - Keynote pdf
Tides - Keynote pdf
Wind results from the unequal distribution of solar radiation.
Solar radiation is distributed unequally because Earth is curved.
Solar radiation strikes Earth perpendicularly near the equator and comes in parallel near the poles.
Warm equatorial air expands, becomes less dense, and rises.
Rising air froms a low pressure system.
Cold polar air cools, becomes more dense, and sinks.
Sinking air forms a high pressure system.
The atmosphere rises at the equator and sinks at the poles.
The equatorial region is a low pressure system.
The polar regions are high pressure systems.
Earth's rotation causes three circulation cells to form in the Northern Hemisphere and three to form in the Southern Hemisphere.
The atomsphere
Wind belts originate at 30o and 90o, where the atmosphere descends.
Three wind belts form in each hemisphere:
Regions of weak winds form at the equator and 30o.
The region of weak winds at the equator is called The Doldrums.
The region of weak winds at 30o is called The Horse Latitudes.
The Trades and the Westerlies are the primary wind belts that generate surface currents.
The Trades from between 0o and 30o.
The Westerlies form between 30o and 60o.
The primary surface circulation pattern is gyre circulation.
Gyres spin right in the Northern Hemisphere and left in the Southern Hemisphere.
There are five ocean gyres:
Currents that flow along the equator and from the equator to higher latitudes are warm.
Currents that flow under the westerlies and from higher latitudes to the equator are cold.
The names, flow direction, and temperature of North Pacific Gyre currents:
The names, flow direction, and temperature of South Pacific Gyre currents:
Seawater is 95% H20 and 3.5% dissolved constituents (sea salts).
The salinity of seawater is relatively uniform, so small changes are important.
Give the salinity at parts per thousand, ppt.
Average salinity of seawater is 35 ppt (34.7 ppt).
Most seawater constituents are ions.
The major constituents constitute >99% of salinity, therefore the concentrations of the major constituents determine the salinity of seawater.
Six
major constituents:
Chloride and sodium have the highest concentrations, approximately 86% of salinity.
Chloride has the highest concentration approximatley 55%.
Sodium has the second highest concentration, approximately 31%.
Although salinity is relatively uniform, approximately 35 ppt, salinity does vary over a small range.
In the open ocean, salinity generally varies from 33 ppt to 37 ppt.
Despite the small variations in seawater salinity, the relative proportions
of the major constituents are constant.
For example, the Na/Ca, K/Mg, or Cl/SO4 are constant for the most
part in the open ocean.
This concept is termed Marcet's principle (the principle of constant proportions).
Because the principle of constant proportions holds for the major constituents,
and the major constituents essentially determine salinity, only one major constituent
needs to be measured to determine salinity.
Generally, chloride (Cl-) is measured, as it has the highest concentration.
The concentration of the other major constituents are calculated.
The concentrations of the major constituents are conservative.
Conservative properties are
Salinity is altered primarily at the ocean surface by
The salinity of seawater is relatively uniform because the ocean is well mixed.
The mixing time is approximately 1000 yr.
The ocean is well mixed, as the residence times of the major constituents
are much longer than the mixing time of the ocean.
Major constituents have very long residence times, all >1,000,000 yr.
In 1,000,000 years, the ocean mixes itself 1000 times.
The ocean is well mixed, therefore salinity is relatively uniform.
The primary biolimiting nutrients are in trace concentrations: N, P, Si, Fe.
Open ocean water is clear, because the nutrient concentration is relatively low.
The atmosphere is 78% N2 and 21% O2.
The three primary gases dissolved in seawater are N2, O2,
and CO2.
N2 is conservative, whereas O2 and CO2 are
nonconservative.
The concentrations of oxygen and carbon dioxide are both affected significantly
by biological activity and can be altered below the surface.
Hawaiian experiences diurnal tides: two unequal high tides and two unequal
low tides.
The primary tidal variations are that the same point in the tides comes 50 minutes
later each day.
And that the tidal range varies on a monthly cycle.
The Moon Tide
The gravitational attraction of the moon dominates the tides.
If the moon was stationary directly above the equator, two bulges would be generated:
Bulges on opposite sides of the earth are of approximately equal.
The gravity bulge is towards the moon, and the inertia bulge on the opposite
side of Earth.
Daily Variability of the Tides
Two bulges and two areas of low-water level between bulges correspond with
the two daily high and two daily low tides.
High tide is the wave crest and low tide is the wave trough.
As the earth rotates under the bulges, Hawaii experiences two high and low tides
each 24 hr.
But the moon also revolves around the center of the earth-moon system each
24 hr in the same direction that the earth rotates.
An additional 50 min is required for the same location on the earth’s
surface to pass under the moon again.
Tidal day is 24 hr 50 min.
Interference with the two tide wave generated by the Earth-sun system cause
large monthly variations in the tides.
46% of the tide-generating force of the moon.
Monthly Variability of the Tides
Moon orbits around the center of the earth-moon system every 29.5 days.
New and full positions produce constructive interference (spring tide).
1st and 3rd quarter phases produce destructive interference (neap tide).
Maximum tidal range during spring tide.
Minimum tidal range during neap tide.
The notes for the first exam are complete