Chapter 1---Section 1

AtmosphereThin layer of air that forms a protective

covering around the planetMixture of gases, solids, and liquidsExtends from surface to outer spaceMuch different today than from when it was

young

Protective Covering…1. Keeps Earth’s temperature in a range that

can support life2. Protects life-forms from harmful ultraviolet

rays3. Reduces most meteors to dust and gas

before they hit Earth’s surface

Early AtmosphereProduced by erupting volcanoesContained nitrogen and carbon dioxide, but

little oxygenAbout 2 million years ago, early

photosynthetic organisms started to create oxygen.

Composition of the AtmosphereGases

Nitrogen (78%)Oxygen (21%)Water Vapor (0-4%)ArgonCarbon dioxideOther trace gases

SolidsDustPollen

LiquidsFrom erupting

volcanoesCondensed water

vapor in clouds

Humans are causing the composition of the atmosphere to changeCar exhaust contains gases which combine with

oxygen in the presence of sunlight to create smog (brown haze)

Carbon dioxide is increasing due to the burning of fossil fuels. This is leading to an increase in global temperature known as the Greenhouse Effect.

Layers of the AtmosphereTroposphere

Lowest layer (extends up to 10 km)Contains 99% of water vapor and 75% of atmospheric

gasesWhere weather occursTemperature decreases with altitude (because it gets

its heat from Earth’s surface)Stratosphere

directly above the troposphere (extends up to 50 km)Contains the “ozone layer”Temp. increases with alt. (because the ozone traps

sun’s rays)

MesosphereDirectly above stratosphere (extends up to 85 km)Where meteors burn up (shooting stars)Temp. decreases with alt.

ThermosphereDirectly above mesosphere (extends up to 500 km)Thickest layerAurora borealis occurs hereTemp. increases with alt. (molecules are first to

receive sun’s rays)

ExosphereOutermost layer (dissipates into space)Space shuttle/satellites orbit hereTemp. increases with alt.

IonosphereLayer of electrically charged particles within

the mesosphere and thermosphereAbsorbs AM radio waves during the day and

reflects them back at night

Atmospheric PressureForce exerted on an area by the weight of

overlying airGreatest near Earth’s surface and decreases

with altitudeWhy? Because the mass of the gases higher up

in the atmosphere are pushing down on the gases closer towards the Earth’s surface

Ozone LayerFound within the stratosphere (19 km - 48 km)Ozone is made up of three oxygen atoms. It is

different from the oxygen we breathe, which only has two oxygen atoms.

Absorbs most UV radiation that enters the atmosphereToo much exposure can cause skin cancer as well

as damage other life-forms

Chlorofluorocarbons (CFCs) are destroying the ozone layerCome from refrigerators, ACs, aerosol sprays,

and the production of some foam packagingEnter the atmosphere through leaks and when

things containing CFCs are disposed of improperly

One chlorine atom from a CFC molecule can destroy approximately 100,000 ozone molecules!

The destruction of ozone molecules seems to cause a seasonal reduction in ozone over Antarctica called the ozone hole.Starts to decrease in late Aug/early Sep and

reaches its lowest values in Oct. By Dec, the ozone hole is gone.

In the mid-1990s, some governments banned the production and use of CFCs. Since then, their concentration in the atmosphere has started to decrease.

Chapter 1------Section 2

Energy from the SunThe Sun provides most of Earth’s

energy

This energy drives wind, ocean currents, and allows plants to grow, producing oxygen and food for animals

Radiation from the Sun can be:Reflected into space (35%)Absorbed by the atmosphereAbsorbed by land or water

Energy reaches Earth’s surface and heats itHeat - energy that flows from an object with a higher temp to an object with a lower temp

Heat is transferred through the atmosphere in three ways:RadiationConductionConvection

RadiationEnergy that is transferred in the

form of rays or wavesEnergy from the Sun reaches the

Earth in the form of radiant energy.Earth radiates some of the energy it

absorbs back into space.Radiant energy from the Sun warms

your face.

ConductionThe transfer of energy that occurs when

molecules bump into one anotherMolecules in warm objects move faster

than molecules in cooler objects. When objects are in contact, energy is transferred from warmer objects to cooler objects.

As air moves over warm land or water, molecules in the air are heated by conduction (direct contact with the ground).

ConvectionThe transfer of heat by the flow of

materialConvection circulates heat

throughout the atmosphere.Convection Currents form when

cooler, denser air sinks while warmer, less dense air rises.

The Water CycleThe constant cycling of water within

the atmosphere and hydrosphereHydrosphere - a term that describes all of Earth’s waters

Plays an important role in determining weather patterns and climate types

Evaporation- Energy from the Sun causes water to change from a liquid to a gas by this process.

Condensation- when water vapor in the atmosphere cools and changes back into a liquid.

Why doesn’t life exist on Mars or Venus?Mars is a cold, lifeless world because its

atmosphere is too thin to support life or to hold much of the Sun’s heat.

Gases in Venus’ dense atmosphere trap heat coming from the Sun making it way too hot to support life. Living things would burn instantly if placed on Venus’ surface.Avg. temp. 470 ˚C (hot enough to melt

lead!)Life on Earth exists because the

atmosphere holds in just the right amount of the Sun’s energy.

Chapter 1----Section 3

WindThe movement of air from an area of higher

pressure to an area of lower pressureCaused by the uneven heating of Earth’s

surface:Land and water heat up/cool down at different

ratesAngle of incidence of Sun’s rays affects how

much thermal energy different parts of the world receive

Always named for the direction from which they blowEx: An easterly wind blows from the east

toward the west.

Coriolis EffectCauses moving air to turn to the right in the

northern hemisphere and to the left in the southern hemisphere

Caused by Earth’s rotation

Angle of IncidenceEach square meter of area at the equator

receives more energy from the Sun than each square meter at the poles does.

Due to the angle at which sunlight strikes the atmosphere at the poles, it has to travel through a thicker layer of atmosphere meaning it has a greater chance of getting absorbed, scattered, or reflected before reaching Earth’s surface.

Global WindsDistinct wind patterns on Earth’s surface are

caused by:differences in the amount of incoming solar

radiation (insolation).the Coriolis effect.

The Sun’s uneven heating of the Earth’s surface forms giant loops, or cells, of moving air. The Coriolis effect deflects the surface winds to the west or east, setting up belts of prevailing winds that distribute heat and moisture around the globe.

DoldrumsA windless, rainy zone near the equator.

Near the equator, Sun heats the air, causes it to rise, creating low pressure and little wind

The rising air cools, causing rain

Wind BeltsTrade Winds - Blow from the subtropical

highs to the low pressure belt at the equator (easterly)

Prevailing Westerlies - Blow from the subtropical high to the subpolar lows (from west to east)

Polar Easterlies - Blow from the polar highs to the subpolar lows (from east to west)

Jet StreamsNarrow belts of strong winds that blow near

the top of the troposphereThe polar jet stream forms at the boundary of

cold, dry polar air to the north and warmer, moist air to the south.

Moves faster in the winter because the difference between cold air and warm air is greater

Helps storms move across the countryFlows from west to east

Sea & Land BreezesCaused by convection currents over areas

where the land meets the seaSea Breeze

Wind blowing from sea to landForms during the dayCooler, denser air over water has a higher

pressure and flows toward the warm, less dense air over the land

Land BreezeWinds blowing from land to seaForms during the nightCooler, denser air over land has a higher

pressure and flows toward the warm, less dense air over the water