1. Characteristics of the Atmosphere
Unit 4: Sixth Grade

2. Floating Balloon Steven has an uninflated balloon.
He fills the balloon with a gas and ties it closed.
When he lets it go, it floats up into the sky.
Steven wonders what happens to the mass of the uninflated balloon compared to the inflated, floating balloon.
What do you think?
Does the floating balloon have more mass?
Does the floating balloon have less mass?
Do the uninflated and the floating balloon have the same mass?
Explain your thinking
Floating Balloon

3. The atmosphere is the mixture of gases that surrounds the Earth.
It provides you with:
The oxygen you need to breathe
Protection from the Sun’s rays
Atmosphere

4. The Composition of the Atmosphere
Our atmosphere is mostly made up of nitrogen gas (78%)
The oxygen that we depend on only makes up 21% of our atmosphere
The other 1% is made up of argon, CO2, water vapor and other gases.
The Composition of the Atmosphere

5. Atmospheric Pressure and Temperature
What would carrying a column of air that is 700 km high feel like?
You carry this load every day!
While air is not heavy, its weight adds up.
At sea level, a square inch of surface area is almost 15 lb of air.
Carrying this much air on such a small surface is like carrying a large bowling ball on the tip of your finger!!!
Atmospheric Pressure and Temperature

6. As Altitude Increases, Air Pressure Decreases
Our atmosphere is held around the Earth by gravity.
Gravity pulls gas molecules in the atmosphere toward the Earth’s surface, causing air pressure.
As Altitude Increases, Air Pressure Decreases

7. As Altitude Increases, Air Pressure Decreases
Air pressure is the measure of the force with which air molecules push on a surface.
Air pressure is strongest at Earth’s surface because more air is above you.
As you move farther away from the Earth’s surface, fewer molecules are pushing down on you, so air pressure decreases.
As Altitude Increases, Air Pressure Decreases

8. As Altitude Increases, Air Pressure Decreases
Think of air pressure as a human pyramid.
The people at the bottom of the pyramid can feel all the weight and pressure of the people on top.
Air pressure works in a similar way.
As Altitude Increases, Air Pressure Decreases

9. Atmospheric Composition Affects Air Temperature
Air temperature changes as altitude increases.
This difference is due to the way the sun’s energy is absorbed as it moves through the atmosphere.
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Atmospheric Composition Affects Air Temperature

10. Atmospheric Composition Affects Air Temperature
Some parts of the atmosphere are warmer because they contain a high percentage of gases that absorb solar (sun) energy.
Other parts contain less of these gases and are cooler.
Atmospheric Composition Affects Air Temperature

11. Layers of the Atmosphere http://www. youtube. com/watch

12. Layers of the Atmosphere
Based on temperature changes, the Earth’s atmosphere is divided into four layers: the Troposphere, the Stratosphere, the Mesosphere and the Thermosphere.
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These words may sound complicated, but the name of each word gives you some clues about its features.
Layers of the Atmosphere

13. Layers of the Atmosphere
“Sphere” means “ball” which suggests that each layer surrounds the Earth like a hollow ball.
“Tropo” means “turning” or “change” and the Troposphere is the layer where gases turn and mix.
“Strato” means “layer” and the Stratosphere is where the gases are layered and do not mix very much.
“Meso” means “middle” and the mesosphere is the middle layer
“Thermo” means “heat”, and the thermosphere is where the temperatures are the highest.
Layers of the Atmosphere

14. The Troposphere --- Our Layer!
The lowest layer of the atmosphere, which lies next to the Earth’s surface is the troposphere.
Altitude 0- 12,000 Km, miles
It is the densest layer
90% of the atmosphere’s total mass!
Almost all CO2, water vapor, clouds, air pollution, weather and life-forms exist here.
Temperatures vary.
Air pressure varies because of differing temperatures causes the gases to mix
The Troposphere --- Our Layer!

15. The Stratosphere --- Home of the Ozone Layer
Gases in the stratosphere are layered and do not mix as much as the gases in the troposphere.
Altitude: 12,000-50,000 km,
The air is very thin and dry.
The lower stratosphere is very cold (-60 C, -76F), but the temperature rises as altitude increases.
This rise happens because ozone in the stratosphere absorbs the ultraviolet from the sun.
The Stratosphere --- Home of the Ozone Layer

16. The Stratosphere’s Ozone Layer
The gases in the ozone layer rarely mix
One of these gas layers within the stratosphere is the ozone layer.
Ozone is a natural gas that forms a thin shield high up in the sky. It protects life on Earth from the sun's ultraviolet (UV) rays.
Stratospheric ozone is found most often between six and 30 miles above the Earth's surface.
The Stratosphere’s Ozone Layer

17. The Mesosphere --- The Middle Layer
Above the stratosphere is the mesosphere.
The mesosphere is the middle layer of the atmosphere.
Altitude: 50,000 km- 80,000 km The temperature decreases as altitude increases.
The Mesosphere --- The Middle Layer

18. The uppermost layer of the atmosphere is called the thermosphere.
Altitude 80, ,00 km
The temperature increases with altitude.
1,000 C, F
The Thermosphere

19. If you said “yes” you are wrong(so wrong)
This is because temperature and heat are NOT the same thing!
Temperature is the measure of how quickly particles are moving.
Heat is the transfer of thermal energy between objects of different temperatures.
You would think with such a high temperature, the thermosphere would be hot, right?

20. Particles must touch each other to transfer thermal energy.
The density of the thermosphere is so low that there is a lot of space between particles.
Since there is so much space between the particles, they rarely touch each other.
Since they rarely touch, they cannot transfer heat.
Therefore, while the temp is high, the heat is low in the thermosphere!
Temperature vs. Heat

21. One last layer --- The Exosphere
The uppermost layer of the Earth's atmosphere is known as the exosphere. In the exosphere, the atmosphere becomes very thin, and atoms and molecules escape into space. It is thought of as the region where the atmosphere of Earth merges with space.
One last layer --- The Exosphere

22. If you were lost in the woods, you could survive for a few days without food and water.
But you wouldn’t last for more than a five minutes without the atmosphere.
So, if the atmosphere is soooo important that you can’t live without out it for even five minutes --- WHAT IS ATMOSPHERE?
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