1. Atmosphere Climate Ozone
Chapter 20
Atmosphere
Climate
Ozone

2. Layers of the Atmosphere
Troposphere (lowest layer)
Tropopause
Stratosphere
Stratopause
Mesosphere
Mesopause
Thermosphere (highest km)

3. Composition of the troposphere
Less than 2%
H2O vapor (.01%-4%)
Argon gas (1%)
CO2 (0.04%)
Trace gases

4. Structure & Temp of Atmosphere
Look at Fig and Table 20-1
Troposphere = lowest layer; tropics  10 miles (16km); higher altitudes  5 miles (8km)
Water vapor & clouds
Greenhouse gases
Colder w/ altitude (generally)
Pollutants reach top w/in a few days

5. Structure & Temp of Atmosphere cont.
Tropopause ---- separate Troposphere from stratosphere
Stratosphere
- temp increases w/ altitude  40 miles
- contains the ozone shield
- Ozone absorbs UV radiation from the sun &
filters the rays
- No precipitation

6. Global warming
The greenhouse effect is natural and important to keep the earth warm enough for life to exist
Global warming occurs when humans contribute too much of these greenhouse gases leading to a small (1-3 degree C) but significant rise in the global average temperature.
Analogy – Car on a sunny day

8. Build up of Greenhouse gases:
CO2
Fossil Fuel use
Deforestation

9. Methane (CH4) Microbial fermentation (Landfill) Coal and oil deposits
Natural gas pipelines
Cows (manure)
Methane is the second most important green house gas (next to CO2)

10. Nitrous Oxides Biomass burning Chemical fertilizers
Fossil Fuel Burning

11. CFC-Chlorofluorocarbons
Refrigerants
Solvents
Pesticides
Aerosols (Old)

12. Ozone (O3) Tropospheric ozone is BAD
If we breath it, it causes lung damage
It is also a greenhouse gas
Stratospheric ozone is GOOD
It shields us from the harmful UVB rays of the sun.
Ozone depletion is the thinning of the stratospheric ozone shield (mostly over the South Pole)
Analogy – Stratospheric O3 is like sunscreen for the earth.

13. The Making of Ozone O2 + UVB (280 – 320 nm more energetic) O + O
The free O bonds to existing O2 (O + O2)
Ozone is made (O3)
O2 + UVB  O + O ; O + O2  O3

15. The Destruction of Ozone
CFC – chlorofluorocarbons
Cl – FC (UV rays breaks bond)
The free Cl “attacks ozone”
O3 + Cl  O2 + (Cl – O)
Cl – O is unstable so the bond will break and the Cl will “attack” another ozone molecule

17. Greenhouse Effect
Troposphere
Traps heat near the Earth’s surface
Water vapor, carbon dioxide, methane
Globing warming
Ozone shield
Stratosphere
filters UV radiation
Oxygen gas, Ozone gas
Ozone depletion  more UV  cancer
Where?
What Happens?
Which gases?
Problem?

18. The End