The Air
Around You
P. 104 Earth’s Water &
Atmosphere
What is Meteorology?
• The study of weather and the
atmosphere.
– Weather- the condition of
Earth’s atmosphere at a
particular time and place.
Earth’s Atmosphere
IMPORTANCE
• It makes conditions on
the Earth suitable for
living things. Contains
oxygen and other gases
living things need.
• Is constantly changing
Earth’s Atmosphere
• Importance of the
atmosphere:
– The atmosphere helps
keep the planet warm.
• Allows for liquid water.
– Protects from
dangerous radiation.
– Burns up chunks of
rocks (meteoroids)
from space. (meteors)
Composition of Atmosphere
• What gas in the atmosphere makes
up the highest percentage of air?
–A. Carbon Dioxide
–B. Oxygen
–C. Argon
–D. Nitrogen
Composition of Atmosphere
• Contains gases, some of
which organisms need
to live
– Nitrogen
– Oxygen
– Carbon Dioxide
– Water Vapor
– Along with other gasses,
particles and liquids.
Nitrogen
• Most abundant (#1) gas in the atmosphere
• One nitrogen molecule contains 2 nitrogen
atoms. N2
• All living organisms need nitrogen in order to
grow and repair body cells.
Nitrogen
• Nitrogen fixation must
occur to convert N2
into a form that plants
can use. (Nitrates)
• Plants absorb the
nitrogen from the soil.
• Animals eat the plants.
Oxygen
• The second most abundant (#2)
gas O2
• Oxygen is an important ingredient
in the combustion process.
– Burning uses oxygen rapidly.
• Oxygen reacts slowly with metal
objects to produce rust.
• Ozone –three oxygen atoms O3
– Ozone Layer in Stratosphere
– Ozone Hole
Carbon Dioxide
• One molecule has one atom of carbon and
two atoms of oxygen.
• Essential to life.
– Plants must use CO2 to produce oxygen.
– Animals give off CO2 as a waste product.
Carbon Dioxide
• Fossil fuels increase the amount of CO2 in the
atmosphere.
• Earth’s temperature rises as a result.
Other (Trace) Gases
• Nitrogen and
Oxygen make up
99% of the gases in
the atmosphere
• Argon and Carbon
dioxide make up
most of the
remaining 1%
(trace gases)
Other
Gasses
Percent by
Volume
Argon
0.93
Carbon Dioxide
0.036
Neon
0.0018
Helium
0.00052
Methane
0.00015
Krypton
0.00011
Hydrogen
0.00005
Water Vapor
• Is in the form of a gas.
– It is invisible, not the same thing
as steam.
• Varies from place to place.
– Desert, Polar Ice Caps
• Almost no water vapor.
– Tropical Rain Forest
• Five % of the air may be water
vapor
Water Vapor
• Plays an important
role in Earth’s
weather.
• Forms clouds when
water condenses on
particles in the air.
• Leads to precipitation
Particles
• Real world air contains tiny solid and liquid
particles of:
– Dust
– Smoke
– Salt
– Other chemicals