AtmosphereAtmosphereChapter 6Chapter 6

Earth’s AtmosphereEarth’s Atmosphere

Importance of the AtmosphereImportance of the Atmosphere• Atmosphere: thin

layer of air that forms a protective covering around the planet

• Balances heat absorbed (from sun) and heat released (into space)

• Protects us from sun’s harmful rays

What is the atmosphere made up What is the atmosphere made up of?of?

• Mixture of gases, liquids and solids

• Extends from earth’s surface to outer space

• Gases in the atmosphere– 78% : Nitrogen– 21% : Oxygen– 1% : other gases

• 0.93%: Argon• 0.03%: Carbon Dioxide• Vapor, ozone, helium, methane,

krypton, xenon

Atmosphere continuedAtmosphere continued

• Solids in the atmosphere:– dust, salt, pollen

• Liquids in the atmosphere- Small liquid droplets from clouds, volcanic

eruptions

- Mount Pinatubo--- Phillipines

Layers of the atmosphereLayers of the atmosphere

Layers of the AtmosphereLayers of the Atmosphere

• 5 layers, each with own unique properties

• Lower layers– Troposphere– Stratosphere

• Upper layers– Mesosphere, – Thermosphere– Exosphere

TroposphereTroposphere• Lowest layer

• Extends up to 10 km

• Temperature decreases as you go up

• Where all weather occurs• Most of total mass of atmosphere is

located here (ocean, mountains, people, animals, plants etc)

StratosphereStratosphere

• Layer above troposphere

• 10-50km

• Temperature increases as you go up

• Contains Ozone (O3)

– Ozone (O3) : gas that absorbs sun’s

harmful rays (solar radiation)

MesosphereMesosphere

• Layer above stratosphere

• 50-85km

• Temperature decreases as you go up

• Find meteors here

• Most meteors that enter the atmosphere burn up here

ThermosphereThermosphere• Layer above the mesosphere• 85km-500km• Temperature increases as you go up (heated by

radiation from the sun)

• Thickest layer, known for its high temperatures• Air is very thin (molecules very spread apart)• Contains layer-ionosphere (radio waves) and

exosphere

ExosphereExosphere

• Highest layer of the atmosphere (before space)

• 500 km-1,000km, upper boundary 10,000 km (6,200 miles)

• Very thin air (molecules extremely far apart)

• Satellites

• Space shuttle orbits

Glossary WordsGlossary Words

• Atmosphere• Troposphere• Stratosphere• Mesosphere

• Thermosphere• Exosphere• Ionosphere • Water cycle

Energy Transfer in the Energy Transfer in the AtmosphereAtmosphere

Light energy VS Heat EnergyLight energy VS Heat Energy

Energy from the SunEnergy from the Sun• Sun provides most energy on

Earth• Drives ocean and wind currents• Allows plants to grow and

produce food provides nutrition to animals

• Sun’s energy can be…• - reflected back into space by

clouds, atmosphere and Earth’s surface (35%)

• - Absorbed by the atmosphere or Earth’s surface (65%)

HeatHeat• Heat- flow from high temperature to low temperature

• 1) Energy from the sun reaches Earth’s surface• 2) Heat transferred by radiation, conduction,

convection (distributes the Sun’s heat throughout the atmosphere)

RadiationRadiation• Energy transferred in

the form of rays or waves

• Sun reaches Earth in the form of radiant energy

• Feel the Sun’s heat and warmth

ConductionConduction• Transfer of energy that

occurs when molecules bump into one another (direct contact)

• Earth’s surface conducts energy directly to the atmosphere

- As air moves over warm land or water, molecules in air are heated by conduction

ConvectionConvection

• Transfer of heat by the flow of material

• Circulates heat throughout the atmosphere

• Cool air sinks, Warm air rises Convection current

The Water CycleThe Water Cycle

• Hydrosphere: describes all water on Earth• Constant cycling of water within the atmosphere and

hydrosphere- determines weather patterns and climate types

• Water moves from– Earth Atmosphere Earth

• Evaporation Condensation Precipitation

The Water CycleThe Water Cycle• 1) Sun- liquid (lakes,

streams, oceans) gas (EVAPORATION)

• 2) Water vapor cools changes back to a liquid- clouds form (CONDENSATION)

• 3) Clouds grow in droplet size and fall to Earth (PRECIPITATION)

• 4) RUNOFF precipitation to groundwater back to ocean

Questions from Water Cycle Model Questions from Water Cycle Model and Study Cards and Study Cards

• What do you see happening?• What did the ice do to the water that went into

the air?• What happened to the water in the air after it

cooled?• Where did the drops of water (rain) go?

• How was the water in our model heated?• What heats water in the real oceans and lakes?• What did our lamp represent?

Atmospheric PressureAtmospheric Pressure

• Pressure= Force/Area (force exerted on a surface divided by the total area over which the force is exerted)

• Atmospheric Pressure– Air (makes up the atmosphere around Earth)

around you presses on you with tremendous force

Variations in Atmospheric PressureVariations in Atmospheric Pressure• Atmospheric pressure

changes with altitude

• As altitude increases- pressure decreases– Fewer air particles are found

in a given volume

• As altitude decreases pressure increases– More air particles are found

in a given volume

Balanced PressureBalanced Pressure

• Why don’t we feel air pressure?

• Pressure exerted outward by fluids of your body balances the pressure exerted by the atmosphere on the surface of your body

Fluids in her body exert a pressure that BALANCES

atmospheric pressure

PascalPascal• Experiment with a balloon (pg 120)

– Designed an experiment in which he filled a balloon only partially with air. He then had the balloon carried to the top of a mountain. As he predicted, the balloon expanded while being carried up the mountain.

– The amount of air inside the balloon stayed the same, while the air pressure pushing in on it from the outside decreased. The particles of air inside the balloon were able to spread out further

Air movementAir movement• Uneven heating of Earth’s surface causes some

areas to be warmer than others.

• Due to Earth’s curve– Equator receives more radiation (direct) than North or

South poles

Heated AirHeated Air• Convection currents

– Equator: hotter air from suns radiation—less dense (rise)---LOW PRESSURE

– Poles: colder air---more dense (sink)---HIGH PRESSURE

The Coriolis EffectThe Coriolis Effect• Rotation of the Earth causes

moving air and water to appear to turn to the – RIGHT north of the equator

(northern hemisphere)– LEFT south of the equator

(southern hemisphere)

Coriolis Effect + uneven heating of Earths surface Distinct wind patterns which influence weather

Global WindsGlobal Winds• Doldrums :

– near the equator (low pressure area)– Windless, rainy zone

• Trade Winds: – air extending to 30°N & S

– steady winds

• Westerlies: – 30 °– 60° N&S moves opposite trade

wind,– responsible for much movement of

weather in N. Hemisphere

• Easterlies: – Found near the poles

– north pole-move southwest,– south pole- northwest

Jet StreamsJet Streams• Narrow belts of strong

winds that blow near the top of the troposphere (~8mi high)

• The polar jet stream forms at the boundary of cold, dry polar air to the north and warmer, more moist air to the south.

Local Wind SystemsLocal Wind Systems• Smaller wind systems affect local weather• Sea and Land Breezes

– Convection currents over areas where land meets the seawinds

SEA BREEZE LAND BREEZEDuring the day (solar radiation warms the land more than water)

During the night, (land cools more rapidly than water)

Warm air rises over land, Cool air sinks and moves from water towards land

Warm air rises over water, cool air sinks and moves from land toward the water

Sea Breeze (Day)Sea Breeze (Day)

Land Breeze (Night)Land Breeze (Night)

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