Chp 9 The Surface Currents

Milankovitch cycles are driven by ....

- All of the above changes in the shape of Earth's orbit changes in the tilt of Earth's axis of rotation the precession of Earth's axis of rotation

Gyres in the N. Hemisphere rotate _________.

Clockwise

_____ ______ are the most common instruments used to measure the speed and direction of currents.

Current meters

Measuring current directions and speeds by changes in the frequency of sound is based on the _____ _______.

Doppler Effect

The Gulf Stream is fed by the ________ current.

Florida

Cyclical changes in global climate are known as _________ cycles.

Milankovitch

An excellent example of the transport of water into the center of a large gyre is the ________ Sea in the N. Atlantic.

Sargasso

Deep water rises to the surface in areas of _______.

divergence

Bottles that carry postcards in them are sometimes called _____ ______.

drift bottles

The phenomena of stronger currents in the western N. Pacific than in the eastern N. Pacific is called _____ ________.

western intensification

The Sargasso Sea is ...

- All of the above created by an isolated lens of water generated by geostrophic flow. located in the central N. Atlantic Ocean. bordered on the west by the Gulf Stream. covered with floating seaweed.

Western intensification is related to ...

- All of the above increase in the Coriolis effect with latitude. friction between continents and ocean currents/ the changing strength and direction of the trade winds and westerlies with latitude.

Satellites can locate major eddies by monitoring ...

- All of the above sea surface temperature light reflection off the surface sea surface elevation

Wind-driven, open-ocean surface currents travel at velocities of about ____ knots.

0.25 - 1.0

The rate of rotation of large eddies is about ...

0.5 m/s

Geostrophic flow can create mounds of seawater that rise as much as ______ above the equilibrium sea level.

1 meter

The Ekman spiral extends to a depth of roughly ...

100-150 meters

Maximum land ice and minimum water temperatures occurred about _______ years ago.

17,000

A minimum in solar radiation reaching Earth occurred about _______ years ago.

23,000

Surface water is driven at an angle of ____ degrees to the direction of the wind.

45

The Gulf Stream transports more than _______ times as much water as the Amazon River in a given amount of time.

500

The net flow of water set in motion by the overlying wind is at an angle of _____ degrees to the direction of the wind.

90

The changing direction of water movement with depth in response to the overlying wind is called the _______ _______.

Ekman spiral

Water is driven into the center of gyres by _______ _________.

Ekman transport

(T/F) Eddies always rotate clockwise in the N. Hemisphere.

False

(T/F) Geostrophic currents are created by narrow straits.

False

(T/F) Sargassum is a type of jellyfish.

False

(T/F) The Ekman spiral extends to a depth of 300 meters.

False

(T/F) The Ekman spiral is restricted to zones of divergence.

False

(T/F) The Ekman spiral twists to the left in the N. Hemisphere

False

(T/F) The Kuroshio Current flows in the S. Atlantic.

False

(T/F) The North and South Pacific gyres form symmetrically on either side of the equator.

False

(T/F) The West Wind Drift moves to the west around Antarctica.

False

(T/F) Typical speeds for surface currents flow at velocities that are about as fast as the wind.

False

(T/F) When the wind stops blowing, wind driven surface currents stop flowing.

False

(T/F) Wind-driven surface currents flow at velocities that are about as fast as the wind.

False

(T/F) At the bottom of the Ekman spiral, water moves in the opposite direction from the wind.

True

(T/F) Deep water comes to the surface in areas of divergence.

True

(T/F) Ekman transport is 90* to the direction of the wind.

True

(T/F) Meanders in the Gulf Stream can pinch off to form eddies.

True

(T/F) The equatorial countercurrent moves to the east.

True

(T/F) There is no source for dense bottom water in the N. Pacific similar to the N. Atlantic.

True

(T/F) There was a mini-ice age about 11,000 years ago.

True

(T/F) Zones of permanent divergence along the western sides of continents are good fishing grounds.

True

The current that circles the globe around Antarctica is called the ...

West Wind Drift

Surface water sinks in areas of _______.

convergence

Water moving horizontally at the surface toward a region of sinking is called ....

convergence

The eastward flowing current along the equator, under the doldrums, is called the equatorial _________.

countercurrent

Current meters measure ...

current speed current direction

Currents can twist and pinch off rings of water called ______.

eddies

N. Atlantic deep water flows toward the ________.

equator

Large eddies, such as those that spin off the Gulf Stream, may ...

extend all the way to the sea floor. have a diameter as great as 300 km.

The oceans are heated ...

from above

Water movement that occurs as a result of a balance between gravity and the Coriolis effect is called _______ ____.

geostrophic flow

Geostrophic flow occurs when these balance each other ...

gravity and Coriolis effect

The large, roughly circular cells of water that rotate around ocean basins and are driven by the prevailing winds are called ______.

gyres

Microphones placed in the water to detect sound are called __________.

hydrophones

Wind driven currents will continue to move after the winds cease because of ______.

momentum

The extraction of energy from ocean currents has some drawbacks, including ...

the relatively slow speed of most currents the inconvenient location of many currents

The far southern current that circles the globe around Antarctica is called the ____ _____ _____.

west wind drift