Air and the Atmosphere

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.

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

Layers of the Atmosphere

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

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

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

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

Temperatures of the Atmosphere

Air and Air Pressure of the Atmosphere