Ocean currents

At what latitude are the ocean gyres centered?

30 degrees

Name a western boundary current, an Eastern boundary current.

A Western boundary- The Gulf stream An Eastern boundary- The California current

What are eddies and how do they form?

A circular movement of water, counter to a main current, causing a small whirlpool. Eddies form when a bend in a surface ocean current lengthens and eventually makes a loop, which separates from the main current. The Coriolis effect causes cold water eddies to rotate counterclockwise and warm water eddies to rotate clockwise in the Northern Hemisphere while in the Southern Hemisphere cold water eddies rotate clockwise and warm water eddies rotate counterclockwise. There is evidence that the topography of the ocean floor can help eddies to form too. Once an eddy forms, the swirling waters last for at least a few months.

What is a gyre?

A gyre is a large system of circulating ocean currents, caused by the coriolis effect.

What is a monsoon?

A seasonal wind. Due to difference in specific heat capacity on land and water

Why is there no permanent gyre in the North Indian Ocean?

Because of the land barrier at the equator.

What is an Ekman spiral?

Due to the Coriolis effect the current moves 45 degrees to the right in the northern hemisphere and to the left in the southern hemisphere. Frictional drag causes movement of layers below surface. Net transport (Ekman transport) of 90 degrees.

Explain the Coriolis Effect.

Due to the Earth's rotation, causes winds to turn to the right in the Northern Hemisphere and the left in the Southern Hemisphere. Extratropical cyclones rotate counterclockwise in the Northern Hemisphere because the Coriolis effect generates the large-scale air-flow pattern at the edges of the cells.

Describe thermohaline circulation

During thermohaline circulation, water sinks in the cold and highly saline North Atlantic Ocean, then returns to the surface in the Indian and Pacific Oceans via upwelling.

What is the difference between tropical and extratropical cyclones?

Extratropical cyclones and weather fronts form between two air masses. Tropical cyclones form from disturbances within one warm, humid air mass.

What are the two methods to study currents?

Float method- Follow something (a drifter) that's floating and track where it goes. Flow method- measure the current as the water passes by a stationary object.

Explain how the density of an air mass changes at different humidities?

Humid air is less dense than dry air because water molecules have less mass than oxygen molecules and nitrogen molecules.

transverse currents

Move water east to west or west to east

What are the five gyres?

North Atlantic, South Atlantic, South pacific, North pacific and Indian ocean gyre

Explain how the density of an air mass changes at different temperatures?

Warm air is less dense, cold air is more dense, because cold air particles move less. So its more densely packed resulting in it being more dense.

What are surface currents?

driven by wind patterns

Warm water is transported toward the poles on which side of the ocean basins?

western side of the ocean basins

In what direction do gyres move int he northern and southern hemispheres

Northern- Gyres clockwise Southern- Gyres counter clockwise

Frictional drag

causes movement of layers below the surface

Cold water transported from the poles is on which side of the ocean basin?

Eastern side of the ocean basin

Geostrophic Gyres

Gyres in balance between gravity and the Coriolis Effect.

Explain how the density of an air mass change at a different pressures?

Increased pressure = more compressed air = increased density of molecules

What causes the two major types of ocean current?

Surface currents; are wind-driven movements of water at or near the ocean's surface, and thermohaline currents; are the slow deep density-driven currents that affect the vast bulk of seawater beneath the pycnocline.

What is Ekman transport?

The Ekman transport is that of a surface current that distributes heat around the globe, this transport operates 90 degrees to the right of the wind in the northern hemisphere. The Ekman is linked to both upwelling, and downwelling; when the transport is driven towards the coastline it leads to water being forced downward, resulting in downwelling. Whereas when the Ekman is driven in the direction away from the coast line it leads to upwelling.

How does the Coriolis effect differ between Northern and Southern hemispheres.

The effect tends to deflect moving objects to the right in the northern hemisphere and to the left in the southern.

In which side of the ocean basin are fast moving currents found?

The western side.

In which direction do the ocean currents under the Trade Winds flow?

They flow west

Western boundary currents

bring warm water from equator to poles (i.e. Gulf stream) -Fast, deep, narrow

What are thermohaline currents driven by?

density and gravity

What is the definition of downwelling

downward movement of water

Coriolis effect

pulls water 45 degrees to right in northern hemisphere

What is the definition of upwelling

upward movement of water (bringing up nutrients). Water replaced at equator after movement from tradewinds.

Explain the role of density in air movement.

warm rises and cold falls, creating a convection cell