Atmosphere NotesAtmosphere Notes

What are the properties of air?What are the properties of air?

Mass – air consists of atoms and Mass – air consists of atoms and molecules.molecules.

Density – the amount of mass in a given Density – the amount of mass in a given volume of air.volume of air.

Pressure – the force pushing on an area Pressure – the force pushing on an area or surface.or surface.

What is the atmosphere?What is the atmosphere?

The layer of gases that surround the The layer of gases that surround the planet.planet.

Earth’s atmosphere makes conditions on Earth’s atmosphere makes conditions on Earth suitable for living things.Earth suitable for living things.

Composition?Composition?

78% nitrogen, 21% oxygen, and 1% argon and other gases.

What’s in the What’s in the other 1%other 1% ? ?

Argon gasArgon gas ““Greenhouse Greenhouse

Gases” like…Gases” like…

carbon dioxidecarbon dioxide

water vaporwater vapor

methanemethane

and moreand more

Atmospheric PressureAtmospheric Pressure Air pressure is greater Air pressure is greater

near the Earth’s surface. near the Earth’s surface. This is because there are This is because there are more molecules in the air more molecules in the air near the Earth’s surface near the Earth’s surface than at the top of the than at the top of the atmosphere.atmosphere.

As you move up from sea As you move up from sea level, air pressure level, air pressure decreases because there decreases because there is less density of particles.is less density of particles.

Atmospheric PressureAtmospheric Pressure

Heated Air – Less Dense and exerts a Heated Air – Less Dense and exerts a lower pressurelower pressure

Colder Air – Higher density of molecules Colder Air – Higher density of molecules and exerts a higher pressure.and exerts a higher pressure.

What is a barometer?What is a barometer?

A barometer is the instrument we use to A barometer is the instrument we use to measure air pressure.measure air pressure.

Read pages 510-511, fill in definitions on Read pages 510-511, fill in definitions on your notes.your notes.

Air pressure and altitudeAir pressure and altitude

Altitude is your height above sea level.Altitude is your height above sea level.Higher altitude=low pressureHigher altitude=low pressureLower altitude=higher pressureLower altitude=higher pressure

That’s why it’s colder higher in the troposphere (bottom layer).

Mount Charleston, Nevada

TroposphereTroposphere

Layer of the atmosphere closest to the Layer of the atmosphere closest to the Earth's surface Earth's surface

Tropo means “turning” or “changing”.Tropo means “turning” or “changing”. It contains 75% of the atmosphere's mass It contains 75% of the atmosphere's mass Temperature and pressure decrease as Temperature and pressure decrease as

you go higher up the troposphere you go higher up the troposphere Where weather occursWhere weather occurs

0-12 km

StratosphereStratosphere

Layer directly above the troposphereLayer directly above the troposphereStrato means “layer” or “spreading out”.Strato means “layer” or “spreading out”.Lower portion of the stratosphere has the Lower portion of the stratosphere has the

ozone layer.ozone layer.This temperature increase with altitude is This temperature increase with altitude is

the opposite of the situation in the the opposite of the situation in the tropospheretroposphere

Airplanes travel hereAirplanes travel here

12-50 km

Ozone LayerOzone LayerThe ozone layer The ozone layer

protects us from protects us from ultraviolet ultraviolet radiation.radiation.

The ozone layer The ozone layer absorbs most of absorbs most of the sun’s UV the sun’s UV radiation before radiation before they reach us.they reach us.

As the radiation is As the radiation is absorbed, the absorbed, the earth’s atmosphere earth’s atmosphere heats up.heats up.

Ozone is good in the upper atmosphere, Ozone is good in the upper atmosphere, but it is NOT good to breathe.but it is NOT good to breathe.

OXYGENOZONE

Scientists study the ozone layer.Scientists study the ozone layer.

One group of gases is particularly damaging to the ozone layer. These gases are called CFCs, (Chloro-Fluoro-Carbons). CFCs destroy ozone molecules.

Most countries have started using different substances in place of CFCs andthe whole in the ozone layer is shrinking.

MesosphereMesosphere

cold layer of the atmosphere, directly cold layer of the atmosphere, directly above the stratosphere above the stratosphere

Meso means “middle”Meso means “middle” temperature generally decreases with temperature generally decreases with

increasing altitudeincreasing altitudeMeteors burn up in this layerMeteors burn up in this layer

50-80 km

ThermosphereThermosphere

temperature is hot and may be as high as temperature is hot and may be as high as thousands of degrees thousands of degrees

Thermo means “heat”Thermo means “heat”Very few molecules in this layerVery few molecules in this layerDivided into the Ionosphere and the Divided into the Ionosphere and the

Exosphere.Exosphere.

80 km and up

IonosphereIonosphere

This layer contains ions (electrically This layer contains ions (electrically charged particles.charged particles.

Auroras occur here because particles from Auroras occur here because particles from the sun enter the ionosphere near the the sun enter the ionosphere near the poles and they strike the nitrogen and poles and they strike the nitrogen and oxygen making them electrically charged. oxygen making them electrically charged. This causes the molecules to glow.This causes the molecules to glow.

80 – 550 km

ExosphereExosphere

Exo means “outer”Exo means “outer”Satellites & the space station orbit hereSatellites & the space station orbit hereThis layer does not have a distinct end, This layer does not have a distinct end,

but instead just merges into outer space.but instead just merges into outer space.

550 km and up