1. Air and the Atmosphere

2. Weather and the Atmosphere
Weather is the condition of the Earth’s atmosphere at a particular time and place.
Earth’s atmosphere is the envelope of gases that surround the planet.
The atmosphere is made of many types of gases as well as dust, salt, and other chemicals that are too small to see.

3. Gases in the Air Nitrogen – N2 – The most abundant type of gas – 78%
Oxygen – O2 – Used by plants and animals, needed for burning – 21%
Carbon Dioxide – CO2 – Used by plants to make food, is released when coal/gas are burned - < 1%
Water Vapor – H2O – Can vary greatly from place to place and time to time - < 1%
Other – Argon, Neon, Helium, Methane, Krypton, Hydrogen

5. Layers of the Atmosphere

6. Troposphere
Means “turning” or “changing” because of its variable conditions
Goes from 0 km to 12 km above sea level
Weather occurs here including rain, snow, storms, and most clouds
The higher you go, the lower the temperature
At the top, it is about -60°C and water forms thin, feathery clouds of ice

7. Stratosphere Means “layer” or “spread out”
Goes from 12 km to 50 km above sea level
Contains the ozone layer which is made from O3 and protects us from ultraviolet rays
The higher you go the warmer it gets because the ozone layer absorbs energy, heating up the air

8. Mesosphere Means “middle” Goes from 50 to 80 km above sea level
Protects the Earth from being hit by most meteoroids
What we see as shooting stars or meteors are trails of hot, glowing gases of meteoroids burning up
Temperatures decrease to -90°C

9. Thermosphere Means “heat”
Goes above 80 km and has no definite outer limit
Blends gradually with outer space
Gets very hot (1,800°C) because the sun hits it first
Has two layers: the ionosphere and exosphere
The ionosphere goes till 400 km and is where we see the Northern Lights

10. Temperatures of the Atmosphere

11. Air and Air Pressure of the Atmosphere