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Oceanography Exam 2
Water & Seawater, Air Sea Interaction, Ocean Circulation
26
Other
Undergraduate 1
03/08/2010

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Term
Describe the dipolar structure of the water molecule and how this aids in dissolving substances.
Definition
Water molecules are made up of 2 Hydrogen atoms and 1 Oxygen atom. They are clustered together in the shape of "Mickey Mouse" ears. The hydrogen atoms give off a positive charge, and the oxygen atoms give off a negative charge. When combined with other substances, the atoms break up and reattach to the molecules of whatever is being dissolved.
Term
Why is ice less dense than water?
Definition
Because the molecules form hexagonic structures when they freeze, leaving space between the atoms, making it less dense.
Term
At what temperature is water most dense?
Definition
Just before freezing - 4degrees.
Term
What controls surface water temperature throughout the world's oceans?
Definition
Solar energy.
Term
What is salinity and what is the average salinity of seawater?
Definition
Salinity is the total amount of solid material dissolved in water. The average salinity of seawater is 3.5%.
Term
What are the two must abundant elements dissolved in seawater?
Definition
Sodium & Chloride (Salt)
Term
Describe how four major processes affect ocean salinity.
Definition
Evaporation and Forming Glaciers add salinity; Precipitation and melting glaciers reduce salinity.
Term
How do changes in temperature and salinity affect the density of seawater?
Definition
Temperature drives processes that change salinity. The cooler the temperature, the greater the density. The more salinity, the greater the density.
Term
What is a thermocline and how does it develop differently in different climates?
Definition
A thermocline is the range of depth in the ocean below which there is a rapid change in temperature. In polar waters, there is no thermocline. In tropical waters, there is. The thermocline acts like a barrier, preventing surface water and deep water from mixing. (It is created by the sun's rays not reaching below a certain point.)
Term
What causes uneven solar heating on the Earth?
Definition
The angle of the sun's direct rays on the planet.
Term
How does air density vary with air temperature?
Definition
The warmer the air, the lower the density. The colder the air, the higher the density.
Term
What causes air masses to move horizontally? (What causes winds?)
Definition
Variations in air pressure. Areas of high air pressure always seek to move to areas of low air pressure to even out.
Term
How is a pressure gradient created?
Definition
Winds are the result of pressure gradients. There are areas of High pressure and areas of Low pressure. The air pulls downward and out in areas of high pressure. The air pulls up and out in areas of low pressure, causing a constant cycle.
Term
Explain how air masses would move on a non-rotating Earth.
Definition
The cold air would sink and the warm air would rise. The air from the poles would move toward the equator, and the air from the equator would move toward the poles, creating a cycle.
Term
How does air generally move at the equator? Why?
Definition
There is no wind. The air is rising, because warm air rises since it's less dense.
Term
What is the Coriolis effect?
Definition
Anything that moves and has mass bears to its right.
Term
Why is there generally very little wind at the equator?
Definition
Because it's not between pressure systems.
Term
How do local wind patterns, such as sea breezes and land breezes form?
Definition
Influenced by variations in topography, land use, and water bodies. Sea breeze = land heats up faster than the ocean. Land breeze = land cools down faster than the ocean.
Term
How do gyres form?
Definition
Fictional drag between wind and ocean - plus distribution of continents, gravity, and coriolis effect.
(Gyre = large circular loops of moving water.)
Term
What is the Ekman spiral and Ekman transport?
Definition
The Ekman spiral = each successive layer of water moves more to its right, forming a spiral.
The Ekman transport = movement of ocean surface water due to wind (90 degrees to the Right).
Term
What forms the "mound" of water within the gyre and why is it not located in the middle of the gyre?
Definition
The Ekman transport and the Earth's rotation form the mound. It is not located in the center due to the Coriolis effect.
Term
How and why are western boundary currents different from eastern boundary currents?
Definition
Western boundary currents are faster and deeper than eastern boundary currents because of western intensification.
Term
What is western intensification and what causes it?
Definition
Because the earth rotates faster than the water moves, so water pushes up against the continents, causing a narrower path - forcing the water to move faster and deeper.
Term
How do surface currents influence the weather in San Francisco and Washington D.C.?
Definition
They transport heat energy. The cold ocean currents carry cold air, which makes the climate colder.
Term
How do changes in temperature and salinity drive deep-ocean circulation?
Definition
All deep-ocean currents start at the surface, then gravity pulls them down once they become dense enough. Temperature and salinity drive surface water density.
Term
How can a change in the thermohaline circulation affect Earth's climate?
Definition
Cold surface water sinks near polar regions and moves toward equator.
Upwelling and downwelling could cause glaciers to form or melt, causing and Ice Age or global warming.
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