Air and the Atmosphere

Weather and the AtmosphereWeather 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 AirNitrogen – 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

Percentage of Gas in Atmosphere

NitrogenOxygenOther

Layers of the Atmosphere

TroposphereMeans “turning” or “changing” because of its

variable conditionsGoes from 0 km to 12 km above sea levelWeather occurs here including rain, snow,

storms, and most cloudsThe higher you go, the lower the temperature At the top, it is about -60°C and water forms

thin, feathery clouds of ice

StratosphereMeans “layer” or “spread

out”Goes from 12 km to 50

km above sea levelContains 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

MesosphereMeans “middle”Goes from 50 to 80 km

above sea levelProtects 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

ThermosphereMeans “heat”Goes above 80 km and has

no definite outer limitBlends gradually with

outer spaceGets 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