1. Section 11.1 – Atmosphere Basics
8th Grade Earth and Space Science
Class Notes

2. Atmosphere Basics
Combination of gases, dust, water droplets, and ice crystals
Surrounds the Earth
Extends from the Earth’s
surface to outer space
Picture of the Earth’s
atmosphere taken
from a space shuttle

3. Permanent Atmospheric Gases
Earth’s atmosphere consists mainly of nitrogen (78 percent) and oxygen (21 percent).
The amounts of nitrogen and
oxygen in the atmosphere are
fairly constant over recent
time.

4. Variable Atmospheric Gases
The concentrations of some atmospheric gases are not as constant over time.
The amount of water vapor, ozone, and carbon dioxide vary significantly from place to place.

5. Water Vapor (H2O(g)) Invisible, gaseous form of water
Can range of 0% - 4%
Concentration depends on the seasons, altitude, and properties of the surface underneath

6. Carbon Dioxide (CO2)
During the past 150 years, the concentration of atmospheric carbon dioxide has increased, due primarily to the burning of fossil fuels.
Currently 0.039% (up by 0.028%)

7. Ozone (O3) Mostly in ozone layer (20 – 50 km above)
Only % but plays important role in blocking out harmful rays from the sun
Concentration has decreased due to CFCs
which are now banned
Scientists estimate it should
fully recover by the 2100

8. Atmosphere Particles
Contains variable amounts of solids in the form of tiny particles, such as dust, salt, and ice
Fungi and bacteria are often attached to these particles
Fluorescent sample
of bacteria taken
from the air.

9. Atmospheric Layers

10. Troposphere Closest to the Earth’s surface
Contains most of the atmosphere’s mass
Weather occurs in this layer
Air temperature decreases with altitude
Top is called tropopause

11. Stratosphere Above tropopause Contains the ozone layer
Air temperature increases with altitude since the ozone layer absorbs the sun’s energy
Ends at the stratopause

12. Mesosphere Above the stratopause
Air temperature decreases with altitude since very little solar radiation is absorbed
Ends at mesopause

13. Thermosphere Low air density so temperature rises (can be over 1000°C)
Contains the ionosphere (made up of charged particles)
Ends at thermopause

14. Exosphere Outermost layer
Transitional region between the Earth’s atmosphere and outer space

15. Review of Thermal Energy and Heat
Remember – all matter is made of particles in constant, random motion!
These moving particles contain kinetic energy.
The total kinetic energy of the moving particles is called thermal energy.
Less thermal
energy 
More thermal
 energy

16. Review of Thermal Energy and Heat
Heat is the transfer of thermal energy from regions of higher temperature to regions of lower temperature
Direction of movement 

17. Energy Transfer in the Atmosphere
In the atmosphere thermal energy is transferred by:
Radiation
Conduction
Convection

18. Radiation Transfer of thermal energy by electromagnetic waves
Thermal energy is transferred from the Sun to Earth by radiation

19. Absorption and Reflection
Incoming solar radiation is either reflected back into space or absorbed by Earth’s atmosphere or its surface.
30% reflected
20% absorbed
by atmosphere
and clouds
50% absorbed
by Earth’s surface

20. Solar Radiation Around
Rate of Absorption
Depends on physical characteristics of the surface and the amount of solar radiation
Examples – water heats and cools more slowly; dark colors absorb energy faster
Solar Radiation Around
the World
Darker = more

21. Conduction
Transfer of thermal energy when objects at two different temperatures are in contact
Occurs between the Earth’s surface and lowest part of the atmosphere

22. Convection
Remember – convection is the transfer of thermal energy by the movement of heated material from one place to another
Near the Earth’s surface air becomes heated, expands, and rises then as it rises it cools, contracts, and sinks.
This creates convection currents in the atmosphere.