Atmosphere
Gasses Notes
I. The Earth’s Atmosphere is a layer of air surrounding the Earth
that supports and protects life by:
1. Absorbing harmful radiation
2. Maintaining the Earth’s temperature
3. Providing elements essential for life
A. Our atmosphere is a mixture of gasses that is held around the
planet by gravity.
B. The atmosphere has both physical and chemical properties.
1. Density (physical property)
- density of the atmosphere decreases with altitude
2. Composition (chemical property)
- 78.08% Nitrogen
- 20.94% Oxygen
- 0.93% Argon
- 0.04% Carbon Dioxide
- 0.01% Other Elements
- 0-4% Water Vapor
II. Energy from the Sun heats the atmosphere.
A. Most energy on Earth comes from the Sun in the form of visible
light.
B. Visible light is a form a radiation that moves in electromagnetic
waves.
- 30% of the sun’s radiation is reflected by clouds, the
atmosphere, and Earth’s surface.
- 70% of solar radiation is absorbed and becomes
different forms of energy.
Gases in the atmosphere absorb radiation.
A. Gasses can absorb and give off radiation.
1. In the stratosphere, ozone gas absorbs ultraviolet
radiation.
2. In the troposphere, Carbon Dioxide, Methane, Water
Vapor, and Nitrous Oxide absorb and emit infrared
radiation.
B. The ozone layer protects life from harmful radiation by
absorbing ultraviolet (UV) rays.
1. Ozone is a gas made up of 3 bonded oxygen atoms – O3
2. UV rays can cause sunburn, skin cancer, & damaged
eyesight.
C. The greenhouse effect keeps the Earth warm.
1. Water vapor, carbon dioxide, methane, nitrous oxide, and
some other gasses are known as green house gasses.
2. These gasses absorb and give off infrared radiation
through a process called the Greenhouse Effect.
GREENHOUSE EFFECT:
 Solar Radiation heats Earth’s surface, which
grows warm and emits infrared radiation.
 Greenhouse gasses absorb some of this
infrared radiation and allow the rest to pass into
space.
 Greenhouse gasses then emit infrared
radiation. Some is absorbed by the ground,
while some is lost to space.
Human Activities affect the atmosphere.
A. Human activity can cause air pollution.
1. Air Pollution consists of gases and particulates.
a. Gases include: methane, ozone, carbon monoxide,
sulfur oxides, & nitrogen oxides.
b. Particulates include: dust, dirt, pollen, and sea
salt.
2. Air pollution can be caused naturally (volcanoes) or by
human activities (burning fossil fuels).
B. Human activities are increasing greenhouse gasses.
1. When greenhouse gasses increase, global temperatures
increase.
2. Increased greenhouse gasses may lead to global
warming or global climate change.
C. Human activities produce chemicals that destroy the ozone
layer.
1. Chlorofluorocarbons (CFCs) are chemicals that were
once used in cooling systems, spray cans, and foam
packing that react with sunlight and destroy ozone
molecules. Substitute chemicals that destroy ozone
more slowly are now used.
2. Chemical reactions in the stratosphere that produce
and destroy ozone depend on the weather. Much of the
ozone over the South Pole is destroyed in certain
seasons, resulting in the “Ozone Hole”.