1. Unit: Weather and Climate
Topics to Discuss this Unit:
Atmosphere + The Sun
Air Pressure + Wind
Water Cycle + Precipitation
Violent Weather
Climates of the World
Weather Maps

2. Introduction to Atmosphere
Atmosphere is a layer of gases surrounding the planet Earth.
This layer of gases protects life on Earth.

3. Gases Nitrogen: 78% Oxygen: 21% Carbon dioxide: 0.03%
Other important gases:
Water Vapor (cause of clouds) and Ozone (absorbs UV rays) are important

4. Oxygen/Carbon Dioxide

5. The Earth's atmosphere contains several different layers that can be defined according to air temperature

6. Troposphere: 1st 10 km
80% of the total mass of atmosphere
Majority of weather occurs here
Environmental Lapse Rate: 6.5° Celsius per meters drop in temperature or 1 ° per 150m
Narrow transition zone - Tropopause

7. Stratosphere:
10 to 50 km
19.9% of atmospheric mass
Heated by absorption of UV (Ozone layer) - greater the height, greater the temperature
Most airplanes fly here, as air is more stable
Jet stream [Strong wind currents]
Narrow transition zone - Stratopause

8. The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains high concentrations of ozone (O3) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere.

10. Mesosphere: km
Coldest temperatures
Temperature decreases with altitude
Meteors burn up in this layer, due to friction
Narrow transition zone – Mesopause
Not well-explored- between maximum altitude for aircraft and minimum altitude for spacecraft

11. Thermosphere: km
Few air molecules, so heats the thin air.
High temperatures >2000 degrees Celsius
Even though the temperature is so high, one would not feel warm in the thermosphere.
Why? because it is so near vacuum that there is not enough contact with the few atoms of gas to transfer much heat.

12. Temperatures climb sharply in the lower thermosphere (below 200 to 300 km altitude), then level off and hold fairly steady with increasing altitude above that height. Solar activity strongly influences temperature in the thermosphere. The thermosphere is typically about 200°C hotter in the daytime than at night, and roughly 500°C hotter when the Sun is very active than at other times.

13. Although the thermosphere is considered part of Earth's atmosphere, the air density is so low in this layer that most of the thermosphere is what we normally think of as outer space. In fact, the most common definition says that space begins at an altitude of 100 km (62 miles), slightly above the mesopause at the bottom of the thermosphere. The space shuttle and the International Space Station both orbit Earth within the thermosphere.

14. Exosphere:
End of the Earth’s atmosphere
This is where the atmosphere thins out and merges with space
There is no clearly discernable boundary between the thermosphere and exosphere

15. Not all scientists agree that the exosphere is really a part of the atmosphere. Some scientists consider the thermosphere the uppermost part of Earth's atmosphere, and think that the exosphere is really just part of space. However, other scientists do consider the exosphere part of our planet's atmosphere.