chapter 1---section 1. atmosphere thin layer of air that forms a protective covering around the...
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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
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