Ocean Dynamics - AP Environmental Science

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Question

Why do storms in the Southern hemisphere swirl clockwise, while storms in the Northern hemisphere swirl counterclockwise?

Answer

Physics describes the Coriolis effect as "the deflection of a moving object due to a rotating reference frame." When the motion is clockwise, the deflection is to the left. When motion is counterclockwise, the deflection is to the right. Put into context: Earth's major wind patterns dictate ocean currents (the object) for the most part—however, the rotation of the Earth deflects surface currents at an angle of about 45 degrees to the wind. The result is a rightward deflection in the Northern hemisphere, and a leftward deflection in the Southern hemisphere.

Eckman transport is the change in wind direction correlating to altitude due to the varying effect of surface friction. Thermohaline circulation is the pattern by which the density of water increases as it becomes colder and saltier; thus it sinks at high latitudes and is replaced by warmer water from the tropics flowing north. This is a key mechanism that regulates Earth's climate. While different hemispheres experience different amounts of heat/light, this is not the reason for the phenomenon described in the question. Finally, ocean currents do not have the ability to dictate storm currents.

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Question

The Coriolis effect causes currents along the east coast of the United States to move __________ near Florida and __________ near Maine.

Answer

The Coriolis effect, caused by the rotation of the earth, results in clockwise currents in the northern hemisphere and counter-clockwise currents in the southern hemisphere.

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Question

Which of the following pairs of adjectives best describes waters brought to the surface by way of upwelling?

Answer

The process of upwelling brings cold, nutrient-rich waters to the surface that replace warm, nutrient-depleted waters.

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Question

What is the shallowest ocean zone, ending at the high water mark?

Answer

The littoral zone includes the intertidal zone. Outward from shore, the zones are littoral, neritic, pelagic. The benthic zone includes the ocean floor.

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Question

Open ocean is referred to as which zone?

Answer

The pelagic zone extends neither to the sea bed nor the shore - it is open ocean. The littoral zone includes the shore and the benthic zone includes the ocean floor. The profundal zone is only present in inland bodies of water, and begins below the limit of light penetration.

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Question

Which region of the ocean is least likely to contain photosynthetic organisms?

Answer

Since photosynthesis depends upon solar energy, we can deduce that the zone which is least likely to contain photosynthetic organisms is the zone furthest away from the sun, and thus the deepest, lowest level of the ocean. The intertidal zone and zone of coastal upwelling are in fact closest to the coast and sun, while the pelagic zone refers to water which is further from the coast, but includes the surface (though not the sea floor). And the euphotic zone is the uppermost zone, which indeed received sunlight. Thus the least likely of these zones to contain photosynthetic organisms is the abyssal zone, the part of the ocean deeper than about 2,000 m and the deepest of this group.

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Question

On the west coast of North America, nutrient-rich water from the bottom of the ocean 'upwells' to the surface. In which direction will the Coriolis Effect take this new surface water?

Answer

The Coriolis Effect in the northern hemisphere spins surface water clockwise. This means the new surface water will be first taken south and east from its emergence at the west coast of North America, to join the clockwise North Pacific Gyre.

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