Atmosphere &

Weather

Earth Science

Energy Transfer in the Atmosphere

Earth’s energy is provided by the SUN!

Energy is important to us because it…

1. Drives winds and ocean currents.

2. Allows plants to grow to produce food.

3. Provides nutrition for many animals.

When Earth receives energy from the Sun… What three things happen to that energy???

1. Reflected back into space.

2. Absorbed by the atmosphere.

3. Absorbed by the land and water.

Does land or water absorb the Sun’s energy faster???

Land…. Why?

•Because it takes more energy to warm up a body of water than it does to warm up an equal area of land.

In what three ways is heat transferred through the atmosphere???

What is radiation???

Radiation is energy that is transferred in the form of rays or waves. Earth radiates some of the energy it absorbs from the sun back toward space.

How can you feel the Sun’s warmth on your face even though you are not in direct contact with the Sun?

What is conduction???

Conduction is the transfer of energy when molecules bump into one another. Molecules are always in motion. When warmer, faster moving objects touch cooler , slow

moving objects energy is transferred.

As air moves over warm land or water, molecules in the air are heated by direct

contact with each other. A process called???

What is convection???

Convection is the transfer of heat by the flow of material. As air is warmed, the molecules move apart = less dense air. Air pressures decreases because the air is less dense. In cold air molecules move closer together so the air is more dense and air pressure increases.

How do convection currents circulate heat throughout the atmosphere???

Convection currents circulate heat throughout the atmosphere by…

As air temperature increases, the air

molecules move apart, and become

less dense.

Air Molecules

Air pressure decreases in warmer temperatures, because fewer molecules are in the same space.

Cooler, more dense air sinks while warmer, less dense air rises, forming a convection current!

Thinking question…

after discussing what happens on Earth to the Sun’s radiation, and how heat can be

transferred…

What do you think helps control how much of the Sun’s radiation is absorbed here on

Earth ???

Why can life exist here on Earth, and not on other planets???

Answer: Because the atmosphere holds just the right amount of the

suns energy!

What is a hydrosphere???

A hydrosphere is the term that refers to all the water on Earth.

The Water C

ycle

and the Hydr

osphere

combined…

What happens to a puddle?

It gets smaller over time because energy from the sun causes the water in the puddle to

change from a liquid to a gas by evaporation.

Water vapor enters the atmosphere. If water vapor in the atmosphere cools enough, it changes

back into a liquid by the process called condensation.

5 types: rain, snow, sleet, hail, freezing rain

Air Movement

Forming Wind

…Remember that the uneven heating of the Earth’s surface by the Sun causes some areas to

be warmer than others…

…Remember that warmer air expands, becoming less dense than cold air… causing air pressure to be

lowered where the air is heated.

So… what is wind???

Wind is

…the movement of air from an area of _higher pressure to an area of __lower___ pressure!

Yes or No…

Do different areas of Earth receive different amounts of radiation from the Sun because the Earth is curved?

Which portion of the Earth receives the most radiation from the Sun?

Answer: The Equator receives more radiation than areas to the North and South.

The heated air at the equator is less dense, so it is displaced by denser, colder air, creating convection

currents.

The cold, denser air coming from the poles, receives less radiation from the Sun, making the air at the poles much cooler. This results in the

dense, high-pressure air sinking and moving along Earth’s surface.

Note: Dense air sinking as less-dense air rises does not explain everything about wind… it is only

one factor in forming wind!

The Coriolis Effect…What is it???

When the rotation of the Earth causes moving air and water to appear to turn to the right North

of the equator and to the left South of the equator.

From what we have just discussed….Can you describe to me what happens to the air

pressure and resulting weather near the equator???

Answer: The Sun heats the air and causes it to rise, creating low pressure and little wind... the

rising air then cools, causing rain (or precipitation)!

Global Winds

Surface Winds

What are the names of the three different surface winds that descend onto the Earth’s surface?

1. Trade Winds

2. Prevailing Westerlies

3. Polar Easterlies

Trade Winds:▪ Also called Tropical Winds▪ Used by sailors to establish early trade routes▪ Found at 30º North and South Latitude

Prevailing Westerlies:▪ Blow in opposite direction from the trade winds▪ Responsible for much of the movement of weather across North America▪ Found between 30° and 60 ° Latitudes

Polar Easterlies:▪ Found near the poles▪ Near N. Pole, they blow from Northeast to Southwest▪ Near S. Pole, they blow from Southeast to Northwest

Winds in the Upper Troposphere

Narrow belts of strong winds, called _______ _____________, blow near the top of the troposphere.

Polar jet streams form at the boundary of cold, dry polar air to the north and warmer, more moist tropical air to the south.

The Jet Stream…▪ Moves faster in the winter because the difference between the cold air and warm air is greater!▪ Helps move storms across the country.▪ Pilots when flying eastward take advantage and save time and fuel.

Local Wind Systems

Global wind systems determine the major weather patterns for the entire planet. Smaller wind

systems affect local weather.

If you live near a large body of water… like an ocean… you are familiar with two such wind systems – sea breezes and land breezes!

Local Wind: Sea Breeze▪ The movement of air toward the land

from the water (sea).▪ Created during the day because solar

radiation warms the land more than the water.

▪ Air over the land is heated by conduction.

▪ This heated air is less dense and has lower pressure.

▪ Cooler, denser air over the water has higher pressure and flows toward the warmer, less dense air.

▪ Resulting in a convection current that blows wind from the sea toward land.

Local Wind: Land Breeze

▪ The movement of air toward the water from the land.

▪ Created at night because the land cools much more rapidly than the ocean water.

▪ Cooler, denser air above the land moves over the water, as the warm air over the water rises.

▪ Resulting in a convection current that blows wind from the sea toward land.