Day 42

Investigation 8 part 2

What Causes Wind

Convection Chamber Review

Conclusion

Warm, less-dense air rose; Cooler, denser air sank

Creates a convection cell

Air sinks because it is denser

Air warmed by candle rose to the top because it is less dense

Air is cooled at the top of the chamber because of the ice

Review Convection Cell on EarthWhere on Earth’s surface could a convection cell develop?

Where Earth’s surface is warm

•Desert

•Tropical ocean

What happens to air pressure

If warm air less dense and rises, what effect do you think that has on air pressure on the ground?

1. As air warms, it expands.

2. Air rises

3. There is less air pushing down

4. Air pressure decreases

What happens to air pressureIf cool air denser and sinks, what effect do you think that has on air pressure on the ground?

1. As air cools, it contracts.

2. Air sinks

3. There is more air pushing down

4. Air pressure increases

Wind

• How can air move sideways across the surface of the Earth?

Wind?

• How is wind made?–Differential heating of Earth’s surface–Energy transfer (radiation, conduction, convection)–Air pressure–Density

• Cause wind?

Wind Concepts

• Differential heating and cooling affects energy transfer to and from the atmosphere

• Warm air expands and is less dense

• Cool air contracts and is denser

• Rising warm air and sinking cool air produce convection currents

Wind Concepts (part 2)

• Dense air produces high-pressure areas, less-dense air produces low-pressure areas

• Differences in atmospheric pressure causes air to move

• Air moving across Earth’s surface is wind

Differential heating and cooling off affects energy transfer to and from the atmosphere

Warm air expands and becomes less dense

Cool air contracts and becomes denser

Rising warm air and sinking cool air produce convection currents

High pressure area

Low pressure area

Wind Concepts

Differences in atmosphere pressure causes air to move

Air moving across Earth’s surface is wind

Multimedia

• Watch the different types of local winds.

• On pages 48 and 49 of the student lab book draw an illustration of the local winds after previewing the multimedia.

• Local weather conditions influence local winds

Which absorbs and releases solar energy faster, landmasses or water?

Energy transfer to and from the air in the atmosphere:1. Conduction (air molecules make contact with land

and water surfaces)

2. Reradiation of energy from the surface

• What happens to air when it is heated?

Air expands and

becomes less dense

What happens to air pressure over the land when air warms and expands? Pressure decreases, local

low pressure forms

Wind

• The horizontal movement of air from an area of high pressure to an area of lower pressure

Naming Local Winds• Local winds are

named based on the direction they come from

• A North wind is blowing from the North to the South

Sea Breeze

• Occurs during the day.

• The flow of air from an ocean or lake to the land.

Land Breeze

• Occurs at night

• The flow of air from land to a body of water.

Valley Breeze

Occurs during the day when air over the mountains heats and rises

The flow of air from the valley up through the mountain

Mountain Breeze

Occurs at night when air cools high in the mountains and sinks into valleys

Labels and Arrows

Visualization Exercise 8.3

Resources, P. 54

Color, Labels, and Arrows

Visualization Exercise 8.4

Images: CD-Rom

Arrows, Color and Real vs Diagram

Visualization Exercise 8.5

Resources, P. 58

Reading

• Starting on page 53 of your resource book read “Where the Wild Winds Blow”.

• Answer the “Think Questions” on page 55.