Transcript Atmosphere chpt 4

Earth’s Atmosphere
Energy Transfer in the Atmosphere
Air Movement
Earth’s Atmosphere
 Atmosphere is a thin layer of air that forms a
protective covering around the planet
 Importance of the Atmosphere: Buffer between space
and the solid earth
 Atmosphere maintain balance between amount of
heat absorbed from the sun and the amount of heat
that escapes back into space
Makeup of the Atmosphere
 Earth’s atmosphere has evolved
 2 billions ya: little O2, large volcanic eruption of
CO2 and N
 Early organisms released O2 when it utilized
sunlight to produce its own food
 Eventually a layer rich in ozone O3 formed to
protect organisms from harmful sun rays
 Plants flourished and as by product of
photosynthesis, O increased
Gases in the Atmosphere
 Nitrogen (N) 78%
 Oxygen (O) 21%
 Water vapor (H2O) up to 4%
 Argon (Ar) and CO2
 Atmosphere composition changes slightly
depending on human interruptions to the
atmosphere
 Smog: brown haze formed from O and other chemicals
in presence of sunlight
 CO2 burned into atmosphere by human activity
Solids and Liquids in Atmosphere
 Dust, salt, and pollen in atmosphere
 Water droplets are moved around the
atmosphere by air currents
Layers of Atmosphere
 Lower layer composed of troposphere
 99% of atmosphere of water vapor and 75%
of gases found here
 Weather occurs in troposphere which
extends 10 km (6 miles) up
 Stratosphere extends above troposphere
and extends to 50 km (30 miles) and upper
layers contain ozone layer
Upper Layer of Atmosphere
 Mesosphere extends 50 and 85 km (30-50 miles)
 Thermosphere extends 85 to 500 km (50-300
miles)
 Ionosphere is found within the mesosphere and
thermosphere where electrically charged particles
are found
 Ionosphere allows radio waves to travel across the
country to another city
 Exosphere has so few of molecules that rocket
wings are useless and that rocket blast are used to
move the shuttle
 Outer space lies farther out
Ozone Layer
 Ozone is an Oxygen compound found in
the stratosphere
 Unlike the Oxygen we breath which is O2, ozone
is O3
 Ozone is important to life on earth because
it absorbs most of the ultraviolet radiation
from the sun
 Ultraviolet radiation is one of many types of
energy that comes from the sun.
 Damage to skin (cancer) occurs from ultraviolet
radiation
Atmosphere Pressure
 Force exerted on an area is known as
pressure
 Gravity pulls air particles to the surface
 The pull is greater closer to the surface
 More gas particles are found at lower
levels
 As move above surface the pressure is
less
Temperature in Atmosphere
 As sunlight passes through the layers of
atmosphere, some gases absorb some of the
sunlight and some gases don’t, the temperatures at
each layer is different
 Troposphere: temperature is warmed by
warming earth’s surface that is transferred to the
troposphere
 As you move upward the temperature
decreases at a rate of 6.5℃ every km (5.5℉
every mile)
 Stratosphere contains the ozone layer that
absorbs some of sun’s energy so as you move
upward the temperature increases
Temperature in Atmosphere
 Mesosphere: temperature decreases with
increasing altitude
 Thermosphere and exosphere are the
first layers to receive the sun’s rays
 Because they are fewer molecules each molecule
have great deal on energy and the temperatures
are high
Ozone Layer
 Ozone is an Oxygen compound found in
the stratosphere
 Unlike the Oxygen we breath which is O2, ozone
is O3
 Ozone is important to life on earth because
it absorbs most of the ultraviolet radiation
from the sun
 Ultraviolet radiation is one of many types of
energy that comes from the sun.
 Damage to skin (cancer) occurs from ultraviolet
radiation
Cfc’s
 Chlorofluorocarbons (Cfc’s) are chemicals
that destroy ozone
 Cfc’s is found in refrigerators, air
conditioners, aerosol cans and production of
some foam packaging
 Destruction is caused when Cl atom
combines with O3 and it breaks apart
forming O2 depleting O3 in atmosphere
 Also the original Cl atom can continue to
break apart O3
Ozone hole
 The study of the atmosphere above Antarctica shows
changing ozone layers where holes have been seen
 Concentrations of Cfc’s since mid 1990’s have been
decreasing helping some
 http://www.theozonehole.com/
Energy Transfer in Atmopshere
section 2
 Heat is energy that flows from an object with a higher
temperature to an object with a lower temperature
 Energy from the sun reaches earth’s surface and heats
it 3 different ways
 Radiation
 Conduction
 Convection
Radiation
 Radiation is energy that is transferred in
the form of rays or waves
 When you face the sun your face is warmed
by that direct contact with radiant energy
Conduction
 Conduction is the transfer of energy that
occurs when molecules bump into one
another
 Energy is transferred from warmer objects to
cooler objects
 Hot sand warms the air directly above it by
conducting heat energy to the atmosphere
Convection
 Convection is the transfer of heat by the
flow of material
 Warm air is less dense and rises,
 It eventually becomes cooler, more dense and
settles back down to surface
 This turning of the atmosphere warms it
 radiation/conduction/convection
Water cycle
 Hydrosphere is the sphere of the earth where water is
 Could be as a liquid, solid or gas
 Water evaporates into the atmosphere where it will
eventually cool, condensation occurs (process of
changing water vapor to a liquid) and it falls back to
surface in form of precipitation
 Water vapor in atmosphere is important in weather
and climate factors to an area
 Yahoo! Video Detail for NASA: The Water Cycle [720p]
Earth’s unique atmosphere
 Atmosphere on earth holds just the right amount of
sun’s energy for life
 The sun’s radiation can be absorbed by the atmosphere
or absorbed by land and water, or be reflected into
space
 Mar’s atmosphere is so thin that the radiation can’t be
absorbed and temp range from 35℃ to -170℃
 Venus’s atmosphere is so thick that it traps sun’s
energy and temp are about 470℃
Air Movement
section 3
 Wind is the movement of air from area of higher
pressure to an area of lower pressure
 Differences in pressure can be caused by uneven
heating of the atmosphere
 Areas of the earth receive different amount of
radiation because of the curvature of the earth
 Poles receive less radiation because of the angle of the
suns rays and thus have cooler temperature
 The air sinks in these areas and moves along earth’s
surface
 At equator, suns rays strike earth directly and warms
faster, rises and is replaced by denser colder air
creating convection currents
Uneven heating caused by earth’s
curved surface
Coriolis Effect
 Coriolis effect is caused by the rotation of the earth
 Affects air and water on earth
 Causes air and water to appear to turn to the right in
the northern hemisphere, in southern hemisphere it
appears to turn left
 Distinct wind patterns develop
Coriolis effect
Global Winds
 Doldrums are areas near equator where
wind doesn’t blow, but rains a lot
 Sailors who relied on winds for their sails
might die of starvation because of lack of
wind on ocean fronts
 Near the equator you have heating and
rising air, creating lower pressure and little
wind
Surface wind
 Trade winds develop at around 30˚ north and south
of the equator
 Air that rose over the equator traveled aloft (above at
high altitude)drops back down the surface
 Air at the surface moves then moves either back
toward the equator in trade winds
 Some air travels away from equator north (northern
hemisphere) to 60˚ N latitude in the prevailing
westerlies wind patterns
 Polar easterlies are found near poles. In N pole it
moves from northeast to southwest
Wind patterns in atmosphere
Winds in Upper Troposphere
 Jet streams (ribbon of air currents aloft) are
boundaries between cold dry polar air and warmer,
moist air in south
 Pilots use it to aid them and save fuel when travel with
stream
 Jet streams also help move storms across the country
Local Wind Systems
 Sea breezes: is created during the day because solar
radiation warms the land more than the water
 Heated air is less dense, rises and at ground air is
replaced by cooler air from seas. Convection currents
occur. You have movement of air from sea to land
 Land breezes: At night the air over land cools faster
than air over ocean, and that cooler denser air moves
toward the ocean. Movement of air toward the water
from the land to sea is land breeze