The Dynamic EarthThe Atomsphere

Objectives (TLW)Explain the composition of the Earth’s atmosphere

List the layers of the Earth’s atmosphere

IntroductionAtmosphere is the mixture of gases the

surround the Earth.Gases in the atmosphere can be added or

removed by natural and unnatural processes i.e. volcanic eruptions, air pollution, living organisms…

The atmosphere is serves as an insulator which slows the rate of heat lose in the Earth.

Composition of the AtmosphereNitrogen enters

Earth’s atmosphere from volcanic eruptions and plant and animal decay.

Oxygen enters Earth’s atmosphere primarily through plants and trees.

Composition of the AtmosphereThe atmosphere also contains tiny particles called

atmospheric dustSoilSaltAshVolcanic ashSkinHairPieces of clothingPollenBacteria and virusesAerosols (tiny liquid droplets)

Composition of the AtmosphereDue to the pull of gravity, the atmosphere is

denser near Earth’s surfaceThe majority of atmospheric gases are

located within 30 km of Earth’s surface.As the elevation increases the air becomes

less dense.

Air is less dense In high altitudesAirplane Mount Everest

Layers of the Atmosphere

The Troposphere18 km above the

surfaceDensest layerTemperature

decreases as the altitude increases

Most of the weather occurs in layer

The StratosphereExtends from 18 km

to an altitude of 50 km

Temperatures increase as the altitude increasesOzone (O3 ) absorbs

UV energy which warms the air.

The MesosphereExtends from 50 km

to 80 km above the surface

Coldest layer

The ThermosphereFarthest from Earth’s

surfaceN and O absorb solar

radiation which results in high temperatures

Air particles are so thin that we would not be able to feel the high temperatures

The lower part is called the ionosphere because of the ions which causes lights

Energy in the AtmosphereSee Figure 15 on page 70Energy from the sun is transferred by three

mechanisms 1. Radiation2. Conduction3. Convection

RadiationIs the transfer of

energy across space and in the atmosphere

Example is heat you feel from a fire is transferred through radiation

ConductionIs the transfer of

energy from a warmer object to a colder object

ConvectionTransfer of heat by

air currents

The Greenhouse EffectThink about how the

inside of a car gets hot on a summer day.

The glass allows solar energy to enter the car which is converted to heat which is prevented from leaving the car because of the glass.

The Greenhouse EffectThe same idea can be

applied Solar energy enters the

Earth through the atmosphere (gases) and is converted to heat

Heat then travels back towards the atmosphere and is absorb by the greenhouse gases which heats the air