chapter15

CHAPTER15The Atmosphere

15-1 CHARACTERISTICS OF THE ATMOSPHERE

Atmosphere A mixture of gases

that surrounds the Earth

Composition Contains gases,

solids, and liquids Solids

Dust, ash, salt, and smoke

Liquid Water


Atmosphere Composition

Gas Nitrogen

78% Released from

volcanoes and decaying organisms

Oxygen 21% Produced by plants

and used by animals Other 1%

Argon Carbon Dioxide Water Vapor


Pressure Air Pressure

Measure of force with which the air pushes on surfaces

Will decrease with Altitude The height of an

object above the Earth’s surface


Temperature Changes as you

increase altitude Results from the way

solar energy is absorbed

Different layers have different gases that absorb energy


Layers Troposphere

Lies next to the Earth’s surface

Lowest and densest layer Contains 90% of

the atmosphere’s mass

Contains all the Earth’s carbon dioxide, water vapor, pollution, and life-forms


Layers Stratosphere

Layer above the troposphere

Air is thin and contains little moisture

Extremely cold at base but temp rises as you go up

Contains Ozone Layer Absorbs UV radiation Ozone

Molecule of 3 oxygen atoms


Layers Mesosphere

Layer above the stratosphere

Coldest layer, -93˚C Contains large wind

storms Winds will reach

320 km/hr


Layers Ionosphere

Between the Mesosphere and Thermosphere

Area where gas particles will become electrically charged Gives off different

colors of light


Layers Thermosphere

Layer above the mesosphere

Temperature will increase with altitude Can reach 1,700˚C Does not feel hot

because particles are far apart

15-2 HEATING OF THE ATMOSPHERE

Energy Radiation

The transfer of energy as electromagnetic waves

Most is reflected Controls convection

and conduction


Energy Conduction

The transfer of thermal energy from one material to another by direct contact

Always moves from warm to cold areas


Energy Convection

Transfer of thermal energy by the circulation or movement of a liquid or gas

Convection current Process of warm air

rising and cool air sinking in a circular motion


Greenhouse Effect Where gases in the

atmosphere trap thermal energy

Allows energy in but will not let it out

If out of balance Earth will heat up

15-3 PRESSURE AND WINDS

Air Movement Wind

The movement of air Created from a

difference in pressure Greater the

difference the greater the speed

Forms because of the unequal heating of the Earth


Air Movement Pressure Belts

Warm air from the equator rises and cold air from the poles sinks

As air warms it creates low pressure

Creates convection cells The circular

patterns caused by the rising and sinking of air


Air Movement Coriolis Effect

Curving of wind by Earth’s rotation

N. Hemisphere curves to the right

S. Hemisphere curves to the left


Wind Types Local Winds

Move short distances and blow from any direction

Global Winds A pattern of air

circulation that moves across the Earth


Wind Types Trade Winds

Winds that blow from 30˚ latitude to the equator

Coriolis effect causes them to curve

Doldrums Where the trade

winds meet Very little wind

because of the warm rising air


Wind Types Westerlies

Wind belt between 30˚ and 60˚ latitude

Flow toward the poles in opposite direction of the trade winds

Polar Easterlies Wind belt that

extends from the poles to 60˚ latitude

Form from cold sinking air


Wind Types Jet Stream

Narrow belts of high-speed winds

Blows around the upper troposphere and lower stratosphere

Does not follow a regular path

Local winds Influenced by

geography Differences between

land and water

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air pushes

cool air sinking

poles sinksas air

different gases

unequal heating

way solar energy

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