Download Composition of the Atmosphere

Earth’s Atmosphere: Composition
Composition of The Earth’s Atmosphere

Nitrogen (N2)
(78.1%)

Oxygen (O2)
(20.9%)

Argon (Ar)
(.9%)

Carbon dioxide (CO2)
(0.03%)

Water vapor (H2O)
(0-4%).
o
These five gases make up 99.99% of the total volume of the atmosphere.

Other
(.17%)

Pollutants
Nitrogen

Most abundant gas in the atmosphere.

Essential nutrient needed by plants and animals.
o
Used as building blocks of protein.

Not used by humans and plants directly from the air.
o
Nitrogen fixing bacteria change nitrogen into a form used by plants roots.
o
Lightning also forms nitrogen that’s usable by plants roots.

Animals get nitrogen from eating plants.
o
Animal waste and dead plants return nitrogen to the air, other bacteria cause it to be returned to the air.
Nitrogen Cycle
Oxygen

Second most abundant gas in atmosphere.

O2 used by animals
o
Oxygen is “removed” by animals as they breath (respiration), “returned” to the atmosphere by plants
(photosynthesis).

O3 known as ozone
o
Ozone protects us from harmful UV rays.
Carbon Dioxide

Used by plants in photosynthesis.
o
Green plants take in carbon dioxide in leaves, used to make their own food.
o
Oxygen is released as a byproduct.
o
Animals give off CO2 as they obtain energy from their food.

Balance of CO2 in atmosphere is constant by plants and animals, but is upset by burning of fossil fuels – green
house effect.

Global Climate Change?
Carbon Dioxide-Oxygen Cycle
Argon and Other Gases

Argon does not combine with any other elements.
o
Atmosphere contains tiny amounts of neon, helium, and other rare gases that are similar to argon.
Water Vapor

Amount in atmosphere varies greatly.
o
Deserts or extremely cold air have almost no water vapor, warm air over oceans has large amounts of
water vapor.
Air Pollutants

Solids.
o
o

Natural sources.

Volcanoes.

Dust from glaciers and erosion.
Human sources.

Smoke from power plants, fireplaces, automobiles.
Gasses.
o
Cars
o
o

Carbon monoxide = poisonous.

Nitrogen oxides and hydrocarbons = cause smog.
Power plants/factories.

Sulfur dioxide and nitrogen oxides = combines with water to form acid = acid rain.
CO2 = Greenhouse gas