The Atmosphere
atmosphere
• definition: the layer of gases that
surrounds the Earth
• weather: the condition of Earth’s
atmosphere at any given time or
place
What gases are in our atmosphere?
•nitrogen (N2) = 78%
•oxygen (O2)= 21%
•trace gases= 1%
argon
CO2
neon
methane
krypton
hydrogen
What are some sources of carbon
dioxide (CO2) in our atmosphere?
• burning fossil fuels releases CO2
into the atmosphere
• Greenhouse Effect- CO2 and
other gases act as a blanket to
hold in heat close to Earth
What else is in our atmosphere?
• Water vapor- from evaporation and
transpiration (1 tree gives off 40,000
gallons of water vapor in a year!)
Solid particles (particulate matter)dust, smoke, pollen, salt, NOX, VOXfrom car exhaust, burning and
volcanic eruptions
ozone
• O3- a form of oxygen with 3 atoms of
oxygen instead
of 2
• the layer of ozone
in the atmosphere
absorbs UV
radiation from
the sun and heats
the Earth
Learn more about the ozone layer:
• http://www.brainpop.com/science/earthsyste
m/ozonelayer/
air pressure
• definition- the weight of a column of air
pushing down on an area
• More dense air has higher air pressure than
less dense air.
• barometer- an instrument used to measure air
pressure
air pressure animation
• http://www.classzone.com/books/earth_scien
ce/terc/content/visualizations/es1901/es1901
page01.cfm?cha
units for measuring air pressure
• inches of mercury- used
with a mercury barometer
• millibars- used on National
Weather
Service maps
altitude
• definition- the distance above sea level
• The higher the altitude the lower the air
pressure.
• animation:
http://www.phschool.com/webcodes10/index
.cfm?fuseaction=home.gotoWebCode
properties of air:
1. mass- even though you can’t see it, air has
mass
How much mass did our balloon have?
How much mass did it have with air blown
inside?
How much was the mass of the air only?
2. density- the density of air near Earth’s
surface is greater than its density at high
altitudes
3. pressure- air exerts a force called pressure
Notes Quiz
1. What is the most abundant gas in
our atmosphere?
2. What are some trace gases that
are in our atmosphere? (name 3)
3. What is ozone?
a) liquid oxygen
b) oxygen molecule with 3 atoms of
oxygen instead of 2
c) a form of rust
4. What are some of the solid
particles in air? (Name 4)
5. Why would there be more
water vapor in a tropical rain
forest than in a desert?
a) the climate is wet in a rain forest
and a lot of water would evaporate
b) there would be a lot of
transpiration from the trees
c) both a and b
• 6. What is air pressure?
• 7. In what 2 units is it measured?
• 8. How is air pressure affected
by density?
9. How is air pressure affected by
altitude?
10. Does air have mass? How do
you know?