The Atmosphere - How
It Makes Life Possible
•
Weather, the condition of Earth’s atmosphere at a particular time and place,
occurs in Earth’s atmosphere.
• The
atmosphere is a thin layer of gases surrounding the earth.
– Greek:
atmos = vapor, sphaira = globe or ball
The Atmosphere - How It Makes Life Possible
• The
atmosphere is composed of:
– Gases
• 78% nitrogen
• 21% oxygen
• 1% other gases
– Solids
• Dust
•
Salt
• Smoke
• Ice
The Atmosphere - How It Makes Life Possible
• The
atmosphere is composed of:
– 78% nitrogen
• Nitrogen is essential to living things.
• Bacteria
convert nitrogen in air into a form that can be used by plants and animals.
The Atmosphere - How It Makes Life Possible
• The atmosphere is composed of:
– 21% oxygen
• Oxygen is required for cellular respiration.
• Ozone,
a type of oxygen, forms when lightning interacts with oxygen in the air.
The Atmosphere - How It Makes Life Possible
• The atmosphere is composed of:
– 1%
other gases
•
CO2
– Animals
produce CO2 and plants use it to survive (photosynthesis)
– Burning
fossil fuels (wood, coal) also produce CO2
• Water
vapor
–
Water in the form of a gas.
– Varies
greatly from area to area (desert or polar ice sheet to rain forest)
The Atmosphere - How It Makes Life Possible
• The atmosphere is important because:
– it
protects living things from harmful UV radiation while allowing light to reach Earth’s surface, supplying energy for
photosynthesis.
– it radiates some heat back
to the Earth, keeping water liquid
– it prevents meteoroids
(chunks of rock) from hitting Earth’s surface.
