Convection Currents & Wind

​Convection Currents & Wind

Unit 1 - Ms. Pineda

What causes wind?

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Essential Question

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Moving air

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What is wind?

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​​On our planet, air is always on the move.

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This movement is caused by changes in air pressure.

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Pressure

Warmer, less dense air rises.

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Cooler, more dense air sinks.

Density​

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The sun's energy provides heat, but Earth does not heat evenly.

The Sun

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• Changes in air pressure.

• The greater the difference in pressure, the faster the wind moves.

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So why does the air move?

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electromagnetic radiation from the Sun

Radiation

conduction from contact with warm land and water

Conduction

convection to even out the temperature and by absorption of infrared radiation from the warm land and water.

Convection

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​Heating the atmosphere

In a high-pressure system, the molecules of cooled air are dense and create "weight" that pushes the air down towards the surface of the Earth.

High Pressure System

In a low-pressure system, the warmed air molecules spread out, become less dense, and rise above Earth's surface.

​​Low Pressure System

Multiple Choice

All locations on the planet do NOT heat evenly.

Where would we expect to find warmer areas on Earth?

• Near the equator

• Near the poles

Multiple Choice

What parts of the planet would be cooler?

• Near the equator

• Near the poles

Multiple Choice

What surfaces on Earth heat more slowly?

• Areas over land heat more slowly

• Areas over water heat more slowly.

Multiple Choice

What does air do as it is heated?

• Heated air rises.

• Heated air sinks.

Multiple Choice

Air that cools becomes ___

• less dense and rises.

• less dense and sinks.

• more dense and sinks.

• more dense and rises.

Multiple Choice

The cooling and sinking of air creates ___ that usually brings light winds, fair weather, and sunny skies.

• high pressure

• low pressure

Multiple Choice

Air that is heated becomes ___

• less dense and rises.

• less dense and sinks.

• more dense and sinks.

• more dense and rises.

Multiple Choice

Warming and rising air creates ___ that usually brings stormy or windy weather.

• high pressure

• low pressure

• Local winds happen in smaller areas of the planet.

• The are caused by areas on the planet that heat at different rates.

• Water and land heat and cool differently.

• High and low altitudes also heat at different rates.

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​Local Winds

• Sea breezes occur in coastal areas during the daytime.

• The wind blows from the sea to the land.

• As the cool, dense ocean air sinks it pushes up the air over the land that has been warmed by the sun.

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Sea Breezes

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• Land breezes occur during the night time in coastal areas.

• Wind blows from the land to the water.

• As the land loses heat the air cools more quickly than the water, becomes dense, and sinks. This pushes the warmer ocean air up.

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Land Breezes

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Multiple Choice

 

Local breezes are created because ___.

• of differences in humidity

• of differences in air temperature

• of differences in cloud cover

Multiple Choice

On a summer day, Thomas is standing in his driveway waiting for his mother. Energy from the Sun is making Thomas feel hot. This energy is being transmitted by three different methods. Which of the following is an example of convection?

• Energy streaming through space toward Thomas​

• Heat being transferred from air particles to the asphalt​

• Heat moving through Thomas’s clothes to warm his skin​

• Warm air rising from just above the asphalt to reach the level of Thomas’s face ​

Multiple Choice

The picture below shows a place where air currents will form due to the uneven heating of Earth. In which direction will air currents most likely move? ​

• straight down over the land 

• from the land toward the sea 

• straight up above the sea 

• from the sea toward the land