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•The conditions of Earth’s
sky at a particular time &
place.
• ATMOSPHERE- a
blanket of gases that
surround the earth.
•600 miles
•Is made up of various atoms
& molecules
•Nitrogen, Oxygen, Carbon
Dioxide, Water Vapor, &
other gases/particles.
Nitrogen 78%
Oxygen 21%
Trace gases & other particles
(Carbon dioxide, Argon...)
1%
Nitrogen
•Most abundant gas in
the atmosphere.
nd
•2
Oxygen
most abundant gas in
the atmosphere
•It is essential for plants &
animals
OZONE
•A form of oxygen with 3
oxygen atoms.
•It protects us from the sun’s
UV rays.
Carbon Dioxide
•Plants need CO2 to
produce food
•Burning fuels release CO2.
WATER VAPOR
• Water in the form of a gas,
invisible
• Helps clouds form
IMPORTANCE OF THE
ATMOSPHERE
1. Contains gases that living things
need
2. Keeps the surface warm
3. Protects us from UV rays
4. Prevents the surface from being
hit by most objects from space.
PROPERTIES OF AIR
Mass, Density, & Pressure.
Mass- the amount of matter
in an object
•Density- the amount of
mass of a substance in a
given volume.
•Density = Mass/Volume
•Pressure- force of an object.
AIR PRESSURE
• The measure of force of the
air pressing down on the
earth’s surface.
Mass & Air Pressure
•In a given volume of air,
More mass = More air
pressure.
•Less mass (less particles) =
Less air pressure.
Barometer
•Instrument that measures
air pressure
•2 types of barometers:
MERCURY BAROMETER
A tube with mercury in the
center, more air pressure
causes the mercury to rise.
Less pressure causes the
mercury to drop.
Aneroid
• An air tight metal box.
• A change in air pressure
causes the needle to move and
gives the new air pressure.
Two common units used to
measure air pressure:
1.Millibars
2. Inches in mercury.
Worldwide Air Pressure
•29.2 inches is the average
•A drop of less than an inch
= major storm
•A rise of less than an inch =
fair weather
ALTITUDE
•the distance above sea level
(elevation).
•As you go higher in
altitude, air gets thinner
(less particles) = less Air
Pressure.
ASea
Level
• Air particles are closer
together so the air is dense.
• More density = More Pressure
•Air at sea level
(bottom book)
4 Layers of the Atmosphere
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
Troposphere
• We live in the lowest layer,
means “changing”
• Earth’s weather occurs here.
• As altitude increases, temp.
decreases 20C
to -60C
Stratosphere
• 12km to 50km above the earth’s
surface.
• Contains the ozone layer
• Lower part cold -60C, upper part
warm 0C because the ozone is
absorbing sun’s energy.
Mesosphere
•Above stratosphere, colder,
middle layer (0- -90C)
•Protects earth’s surface
from being hit by most
meteoroids.
Thermosphere
• Top layer of atmosphere, air so
spread out
• Very hot (1,800C) but doesn’t
read because particles are so
spread out.
• Breaks into 2 layers: ionosphere,
& exosphere
IONOSPHERE
• Lower part of Thermosphere
80-400 KM
• Contains charged particles
(ions) that light up the night
sky- Aurora Borealis
• -90C,
EXOSPHERE
•Top layer of
Thermosphere, 400+km
•No limit, satellites
• Harmful substances in
air, water, or soil.
1. Natural- forest fires, soil
erosion, dust storms,
volcanoes.
2. Human Activities- burning of
fossil fuels (cars, factories,
power plants)
•When fossil fuels burn, they
release particles into the air.
Some of these pollutants
are: carbon monoxide,
carbon dioxide, nitrogen
oxide, & sulfur oxide.
• The burning of fossil fuels
causes smog & acid rain.
• London-Type Smog- using
coal caused particles of coal
smoke to combine with water
vapor producing a dark smog
in England.
London-Type Smog
• Photochemical Smog- a brown
haze in cities, chemicals from
burned fossil fuels mix with
sunlight, ozone, & other
pollutants.
Photochemical Smog
ACID RAIN
•rain that is more acidic than
usual, formed from the
burning of coal which
produces sulfur oxides
which mix with water vapor
in the air.
• In the US, the government has
passed laws to reduce
pollution.
• Environmental Protection
Agency (EPA) monitors air
quality.