# AP Environmental Science : Ocean Dynamics

## Example Questions

### Example Question #1 : Ocean Dynamics

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

Thermohaline Circulation

The Coriolis Force

Ekman Transport

The different hemispheres experience different amounts of heat/light

Water currents in the Southern hemisphere run clockwise and push storm currents in a similar direction

The Coriolis Force

Explanation:

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.

### Example Question #2 : Ocean Dynamics

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

counterclockwise . . . clockwise

clockwise . . . counterclockwise

east . . . west

south . . . north

clockwise . . . counterclockwise

Explanation:

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.

### Example Question #3 : Ocean Dynamics

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

Nutrient-poor and warm

Cold and nutrient-poor

Cold and nutrient-rich

Nutrient-rich and warm

Cold and nutrient-rich

Explanation:

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

### Example Question #4 : Ocean Dynamics

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

Neritic zone

Littoral zone

Pelagic zone

Benthic zone

Littoral zone

Explanation:

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

### Example Question #5 : Ocean Dynamics

Open ocean is referred to as which zone?

Profundal zone

Benthic zone

Pelagic zone

Littoral zone

Pelagic zone

Explanation:

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.

### Example Question #6 : Ocean Dynamics

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

Pelagic zone

Euphotic zone

Zone of coastal upwelling

Intertidal zone

Abyssal zone

Abyssal zone

Explanation:

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.

### Example Question #7 : Ocean Dynamics

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?

South and east, to join the clockwise North Pacific Gyre.

South, to join the North Equatorial Current.

North and west, to join the counter-clockwise North Pacific Gyre.

West, to push more garbage to the Pacific Garbage Patch.

North and west, following the coast of North America.