RFMS Science: Currents & Climates CSA 2 Review

Which is more dense: fresh water or salt water? Why?

• Salt water, because it has more salinity

• Fresh water, because it has more salinity

• Neither of them have density

Answer explanation

Salt water is more dense than fresh water because it contains dissolved salts, which increase its salinity and overall mass per unit volume. This added mass makes salt water denser.

Which condition will most likely lead to the formation of winds on Earth?

• Uneven heating of Earth's surface

• Shifting of tectonic plates

• Geothermal activity in the Earth's core

Answer explanation

Winds on Earth are primarily caused by the uneven heating of the Earth's surface, which creates differences in air pressure. This leads to air movement, resulting in wind. The other options do not directly cause wind.

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How are air temperature, density, and the movement of air related?

• Cold air is more dense than warm air, so it rises to create a convection cell.

• Warm air is more dense than cold air, so it sinks to create a conduction cell.

• Warm air is less dense than cold air, so it rises to create a convection cell.

Answer explanation

Warm air is less dense than cold air, which causes it to rise. This rising air creates a convection cell, as the cooler, denser air moves in to replace it, establishing a cycle of air movement.

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The sun heats the surface of the Earth unevenly, resulting in atmospheric convection currents. What is created due to convection cells?

• wind

• rain

• clouds

Answer explanation

Convection cells, formed by uneven heating of the Earth's surface, create rising and falling air currents. This movement of air generates wind, making it the correct answer. Rain and clouds can result from these processes, but wind is directly created.

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Warm ocean currents are most likely to be located towards the surface of the ocean because

• winds press the cold water down

• warm water is less dense and rises

• cold water is less dense and sinks

Answer explanation

Warm water is less dense than cold water, causing it to rise to the surface. This is why warm ocean currents are typically found near the surface, as they float above the denser, colder water.

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What causes differences in air pressure around the Earth?

• Cold air rises at the equator, and warm air sinks at the poles.

• Warm air rises at the equator, and cold air sinks at the poles.

• Warm air rises at the equator, and cold air rises at the poles.

Answer explanation

Warm air rises at the equator due to heating from the sun, creating low pressure, while cold air sinks at the poles, leading to high pressure. This difference in temperature and pressure drives atmospheric circulation.

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Explain the role of density in the movement of deep currents.

• Cold, high salinity deep current water is less dense than warm, low salinity surface current water. As warm water sinks, cold water will move in to take its place, creating a circular movement called a convection current.

• Cold, high salinity deep current water is more dense than warm, low salinity surface current water. As warm water rises, cold water will move in to take its place, creating a circular movement called a convection current.

Answer explanation

Cold, high salinity deep current water is more dense than warm, low salinity surface current water. This density difference causes warm water to rise and cold water to move in, creating convection currents.

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Within a land breeze or a sea breeze, how does air pressure move?

• North to South

• Low pressure to high pressure

• High pressure to low pressure

Answer explanation

In a land breeze or sea breeze, air moves from areas of high pressure to areas of low pressure. This movement is driven by the difference in pressure, making 'High pressure to low pressure' the correct choice.

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The Gulf Stream is a warm water current that begins in the Gulf of Mexico. A diagram of the Gulf Stream is shown.

Which best describes the movement of the Gulf Stream?

• Cold currents carry cold water from the poles to the equator.

• Warm currents carry cold water from the tropics towards the poles

• Warm currents carry warm water from the equator towards the poles

Answer explanation

The Gulf Stream is a warm water current that transports warm water from the equator towards the poles, influencing climate. Thus, the correct description is that warm currents carry warm water from the equator towards the poles.

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If a cool surface current flows along a coastline, what effect might it have on the climate in that area?

• In general, it will bring cooler temperatures in the summer and milder temperatures in the winters.

• It will not have an effect on the climate.

• In general, it will bring warmer temperatures in the summer and warmer temperatures in the winters.

Answer explanation

A cool surface current along a coastline typically lowers summer temperatures and moderates winter temperatures, leading to cooler summers and milder winters, which aligns with the correct answer.

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