Earth’s Atmosphere Supports
Life
Atmosphere:
• Whole layer of air that surrounds Earth
• Supports life and protects it
• Keeps the Earth warm
Characteristics of the Atmosphere
Altitude:
• Distance above sea level
• Air becomes thinner as altitude
Density:
• Amount of mass in a given volume of a
substance
• If two objects take up the same space,
then the object with more mass has a
greater density. Ex. Bowling ball has more
mass than a soccer ball
• The higher up you move in the atmosphere the
less dense the air is.
Materials in the Atmosphere
• Most are gases
• Some tiny solid or liquid particles such as
dust, sea salt and water
• 78% -Nitrogen makes up most of the air
• 21% is oxygen
• 1% other gases
Natural processes modify the
atmosphere
Ongoing Processes:
Cycles: processes that repeat over and over
1. Carbon / oxygen
2. Nitrogen
3. Water
Carbon / Oxygen Cycle:
• Gases circulate between plants and
animals
»
Take in
Give off
• Animals
Oxygen
• Plants
Carbon dioxide
Carbon dioxide & water
oxygen & water
Carbon / Oxygen Cycle
Nitrogen Cycle:
• Nitrogen cycled through the atmosphere,
soil and living organisms.
• Free nitrogen in the air is “fixed” in the soil
or by lightning.
• Becomes nitrates.
• Plants use the nitrates to grow.
• Animals eat the plants.
• Plants & Animals die.
• Bacteria break down the nitrates and
release free nitrogen into the air.
Water Cycle:
http://www.youtube.com/watch?v=F
9Yi4dAzHsc&feature=related
• Different forms of water cycle between the
Earth’s surface and the atmosphere
• Liquid water changes into gas (evaporation)
• Plants and animals release water (exhale /
transpiration)
• Liquid gas turn into water vapor (clouds)
condensation
• Liquid water falls from the atmosphere (rain/
snow..) precipitation
Sudden Changes
• When sudden events occur, it takes time
before the atmosphere is able to restore
balance.
• Volcanic Eruptions: gases and ash
produce haze that may affect the air for
many months and lower temperatures
worldwide.
Forest Fires:
• The carbon in the trees combines with
oxygen and enter the atmosphere as
carbon dioxide.. Wood ash also enters the
atmosphere
Dust Storms:
• Wind, water or drought can loosen soil.
• Windstorms raise clouds of eroded soil
• Adds huge amounts of particles to the air.