1. The Atmosphere

2. Atmospheric Composition
Grab a handful of air…
Earth’s atmosphere is mostly nitrogen and oxygen
N2 (78%) and O2 (21%) make up 99% of the atmosphere
Less than 1% is other gases, such as argon, carbon dioxide (CO2), methane, water vapor, dust

3. Earth’s Atmosphere

4. Key Atmospheric Gases (Small but mighty)
Water
Amount changes constantly, 0-4%
Source of clouds and precipitation
Absorbs heat given off by Earth and some solar energy
Ozone (O3)
Very small amount (>0.01%)
Absorbs harmful UV radiation
Protects our skin from sun damage
Carbon dioxide (CO2)
0.03%
Absorbs heat, contributes to global warming

5. Human Influences on Atmosphere (Air pollutants)
Depletion of ozone layer by use of chloroflorocarbons (CFCs) – aerosols, refrigerants, some Styrofoam
Automobiles account for 33% of CO2 emissions, contributing to global warming
Air pollution…includes carbon monoxide, nitrogen oxides, sulfur oxides, metals, ammonia, particles (e.g., dust), methane
How does this affect us?
Asthma, lung cancer, respiratory illness, heart disease

6. Primary Pollutants

7. Atmospheric structure
The atmosphere is made up of 4 main layers, determined by temperature and composition:
Troposphere
Stratosphere
Mesosphere
Thermosphere

9. Troposphere Sphere of weather Thinnest layer of the atmosphere
Temperatures decrease with height
(Have you ever been to the top of a mountain?)
Height: 0 to 12 km

10. Snowy Mountaintops Contrast with Warmer Snow-Free Lowlands

11. Stratosphere
Temperatures increase
Ozone layer
Height: 12km to 50km

12. Mesosphere Temperatures decrease Temperatures as low as -90◦ C
Height: 50km to 80km
Meteors are broken up

13. Thermosphere Temperatures increase
Oxygen and nitrogen absorb solar radiation
Northern lights
80km to…? (no defined upper limit)

15. Temperature v. Heat
Temperature: measurement of the kinetic energy (energy of motion) of atoms or molecules
Faster motion = higher temp.
Heat: transfer of energy from one object to another because of a difference in temperature
Heat flows from higher to lower temp.
Radiation, conduction, convection
Heat fuels the weather, and temperature measures it!

16. Pressure-Density-Temperature Relationship
Air pressure: weight of the air pressing down
gases at the top press down on the ones below
Density: measure of particles in a given space
More particles = higher density
Temperature: proportional to pressure, inversely proportional to density
Atmospheric
Relationships
As T ↑ , P ↑
As T ↓, D ↑
As T ↑ , D ↓
T = Temperature
P = Pressure
D = Density
↑ = Increases
↓ = Decreases

17. Air Pressure v. Altitude
Altitude: measure of distance “up” in the air
Pressure ↓ as altitude ↑
Why is it harder to breathe at the top of a mountain?
Components of
the atmosphere