Hydrology Unit Test 2025

Some ocean currents are caused by differences in the density of water from place to place around the globe. What two factors cause differences in ocean water density?

• differences in water temperature and wind
• differences in water temperature and phases of the moon
• differences in the amount of dissolved salts and gravity
• differences in water temperature and amount of dissolved salts

Earth's rotation causes surface currents in the Northern Hemisphere to

• curve clockwise.
• move in straight lines.
• curve counterclockwise
• move in diagonal lines.

Ocean currents are caused by water's density differences. The density differences in the ocean water are due to different salt concentrations and differences in

• waves.
• temperature.
• plate tectonics.
• volcanic activity.

Which best describes the Gulf Stream?

• A cold ocean current that cools the weather off near Australia.
• A cold ocean current that helps decrease global warming.
• A warm ocean current that influences weather along the east coast of the U.S. and up toward Europe.
• A warm ocean current that influences weather in Cuba and moves toward Antarctica.

How do deep ocean currents form?

• The form as warm, dense water sinks and flows beneath cold ocean water.
• They form as cold, dense water sinks and flows beneath warm ocean water.
• They form as warm, dense water sinks and flows with other warm ocean water.
• speed of the wind

Which of the following does NOT control surface currents?

• tides
• global wind
• Coriolis Effect
• continental deflections (bouncing off of the continents)

What phenomenon does the Coriolis Effect arise from?

• Rotation of the Earth on its axis.
• Revolution of the Earth on its axis.
• Effect of winds high in the atmosphere.
• Curvature of the Earth’s surface

What happens to the ocean as depth increases?

• temperature increases
• salinity decreases, temperature decreases
• pressure decreases
• temperature decreases, salinity increases

Which two features together control the density of seawater?

• temperature and sea depth
• salinity and plankton concentration
• temperature and salinity
• salinity and depth

As water gets denser, how does it move? S6E3.d

• expands toward warmer water
• gets pushed toward the poles
• sinks toward the ocean floor
• evaporation