1. Why is it so important to life on earth?
Earth’s Atmosphere
Why is it so important to life on earth?

2. OBJECTIVES: 1. describe the layers of the atmosphere. 2
OBJECTIVES: 1. describe the layers of the atmosphere. 2. differentiate the layers of the atmosphere based on variation of temperature explain the significance of the layers and the boundaries between them.

3. Importance of the Atmosphere
Creates suitable living conditions for life
Living things needs oxygen, warmth and liquid water
Traps solar energy warm enough for water to exist as a liquid
Protects against solar radiation
Helps prevent meteor strikes from space

4. If Earth Had No Atmosphere
No lakes or oceans
No Sounds
No Clouds
No Red Sunsets
Extremely Cold Nights & Hot Days
We could only survive a few minutes
Fun Fact: Any more than 21% oxygen and we would burst into flames from the flammability of oxygen.

5. The Atmosphere
Earth’s atmosphere is a layer of gases surrounding the planet.
The atmosphere protects and supports life.

6. What's in Earth's atmosphere?
Earth’s atmosphere is made of a mixture of gases called air.
78% Nitrogen – released when dead plants and dead animals break down and when volcanoes erupt
21% Oxygen – made by phytoplankton and plants
1% Trace Gases – made up of argon, CO2, water vapor and other gases

7. Nitrogen Cycle
Nitrogen is important to protein which is found in the body tissues of all living things.
Nitrogen is cycled through the soil and into plants and finally when living things die and decay.

8. Density
Air consists of atoms and molecules, which have mass, so…Air Has Mass!
The amount of mass in a given volume of is Density.
Density=Mass/Volume
More molecules in a space mean more density
Less molecules in a space mean less density

9. Air Pressure
PRESSURE is the force pushing on an area or surface. “force per unit area”
The weight of the atmosphere exerts a force on surfaces
AIR PRESSURE is the result of the weight of a column of air pushing down on an area.

10. Pressure in the atmosphere
The gas molecules closest to Earth’s surface are packed together very closely.
This means pressure is lower the higher up you go into the atmosphere.
As altitude increases, temperature decreases.
Lower part of atmosphere is warmer.

11. Pressure changes with Altitude

12. Pressure in the atmosphere
At sea level, the weight of the column of air above a person is about 9,800 Newtons (2,200lbs)
This is equal to the weight of a small car.
Why aren’t we crushed by this pressure?

13. Why aren’t we crushed?
Air pressure doesn’t crush you or anything else around you because the molecules in air push in all directions-down, up and sideways.

14. Earth’s atmosphere is made up of different layers…

15. Layers of the Earth’s Atmosphere
troposphere
stratosphere
mesosphere
thermosphere
> ionosphere
> exosphere

16. Why is the atmosphere divided into different layers?
Any guesses?
The atmosphere is divided into four different layers because the atmosphere is not uniform, its properties change with altitude.
Two properties change with altitude, the AIR PRESSURE and the AIR TEMPERATURE
Lets look at each layer individually.

18. The first layer of the atmosphere is the…
TROPOSPHERE
Lowest and thinnest layer, closest to the Earth’s surface
The layer in which we live
The troposphere goes from 0km to 11km.
All weather happens in the troposphere.
90% of the atmosphere’s total mass is in this layer
The temperature drops as the altitude increases.

19. STRATOSPHERE Extends from 20 km to 50 km Less dense (less water vapor)
Temperature increases with altitude
TEMPERATURE INVERSION
Almost no weather occurrence
Contains the ozone layer
Jets fly in this layer

20. Stratopause
Boundary between the stratosphere and the next layer (the mesosphere) is called the stratopause
Temperature is constant with altitude
From km

21. Ozone Layer
A gaseous layer in the upper stratosphere that protects the earth from harmful ultraviolet radiation
O3 = 3 oxygen atoms in an ozone molecule

22. Ozone Forms naturally in the stratosphere
It is naturally destroyed by U.V. Radiation and creates more O2 (oxygen)
O3 + U.V.  O2 + O
CFC’s are chlorofluorocarbons-pollutants in our atmosphere (chlorine, fluorine, carbon)

23. The third layer of the atmosphere is the…MESOSPHERE
From 50km to 90km.
temperature decreases as altitude increases
Middle layer
The mesosphere is the coldest layer of the atmosphere. (-90 degrees)
Meteors burn up in this layer.

24. MESOSPHERE Very low air pressure as 99% of atmosphere is below it.
Gases are less dense in this layer and absorb very little UV radiation.
Fun Fact: Low air pressure would make your blood boil from the U.V. radiation.

25. THERMOSPHERE From 90km to outer space
temperature increases with increasing altitude
Hot Layer-Temperature can go as high as 1,500 °C
Air molecules are so far apart so the solar energy that is absorbed increases the temperature more.
Edge of the atmosphere
Uppermost layer

26. IONOSPHERE Layer of electrically charged particles called “ions”
Upper mesosphere and lower thermosphere
Nitrogen and oxygen absorb harmful solar energy
Radio waves will bounce off charged particles (ions) back to earth
Auroras or “Northern Lights”
Particles from the sun enter the atmosphere and strike atoms causing them to glow