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Circulation in the Ocean — Reading Comprehension

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Ocean circulation involves the movement of seawater driven by wind, temperature, and salinity. It includes surface currents, deep ocean currents, and the global conveyor belt, which regulates climate and supports marine ecosystems.

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Ocean circulation refers to the large-scale movement of seawater around the globe. It is driven by a combination of factors, including wind, temperature, salinity, and the Earth’s rotation. Ocean circulation plays a crucial role in regulating the Earth’s climate and distributing heat and nutrients.

The ocean’s circulation system is divided into two main components: surface currents and deep ocean currents. Surface currents are driven by wind and affect the upper 400 meters (1,300 feet) of the ocean. Deep ocean currents, also known as the thermohaline circulation, are driven by differences in water density caused by temperature and salinity.

One of the most important features of ocean circulation is the global conveyor belt, a slow-moving current that transports water around the world. Warm surface water flows from the equator toward the poles, where it cools, becomes denser, and sinks. This cold, dense water then flows back toward the equator, completing the cycle.

Ocean circulation also affects marine ecosystems by transporting nutrients and oxygen. For example, upwelling brings nutrient-rich deep water to the surface, supporting plankton growth and, in turn, larger marine animals.

Fun fact: The global conveyor belt takes about 1,000 years to complete one full cycle, making it one of the slowest processes on Earth!

What is ocean circulation?

The movement of air over the oceanThe large-scale movement of seawaterThe formation of wavesThe melting of glaciers

What drives surface ocean currents?

Temperature and salinityWindEarth’s rotationUpwelling

What is the thermohaline circulation?

A surface current driven by windA deep ocean current driven by density differencesA type of waveA process that forms icebergs

What is the global conveyor belt?

A fast-moving surface currentA slow-moving current that transports water globallyA type of upwellingA process that creates waves

What is one role of ocean circulation in marine ecosystems?

It reduces oxygen levelsIt transports nutrients and oxygenIt stops plankton growthIt increases salinity

What is upwelling?

The sinking of cold, dense waterThe rising of nutrient-rich deep water to the surfaceThe formation of wavesThe melting of ice

What is the fun fact mentioned in the passage?

The global conveyor belt takes 1,000 years to complete one cycleOcean circulation has no effect on climateSurface currents are driven by salinityUpwelling stops plankton growth

What is one effect of ocean circulation on climate?

It increases air pressureIt distributes heat around the globeIt reduces rainfallIt stops wind patterns