Atmosphere in Motion
Chapter 12
By Amy Johnson
Atmosphere

gases surrounding the Earth
– necessary for supporting life
– protects against harmful UV and X-ray
radiation
– absorbs and distributes warmth
Galileo Galilei

proved air must have weight and contain
matter
– Weighed flask, injected air, and reweighed to
find flask with injected air weighed more

Air stores and releases heat, holds moisture,
and can exert pressure
Composition of Atmosphere

subject to the pull of gravity
– exerts pressure in all directions, therefore
cannot be felt
– weight is equal to water over 10 m deep

mixture of gases, liquid water, and
microscopic particles of solids and other
liquids
Gases of the Atmosphere
Nitrogen – most abundant (78%)
 Oxygen – necessary for human life (21%)
 Variety of other gases in trace amounts

– water vapor is critical to weather (up to 4%)
» Responsible for clouds and precipitation
– carbon dioxide allows plants to make food
(.03%)
» Absorbs heat and emits it back to warm Earth
Aerosols in the Atmosphere

solids, such as dust, salt, and pollens and
tiny droplets of acid
– dust comes from volcanoes and wind blowing
across the soil
– salt results from wind blowing over the ocean
– pollen is released by plants
– burning coal in power plants also creates
aerosols
Layers of the Atmosphere
based on temperature changes that occur with altitude

Lower Layers
– Troposphere
– Stratosphere

Upper Layers
– Mesosphere
» Ionosphere
– Thermosphere
– Exosphere
Troposphere
closest to the Earth (about 10 km)
 contains about ¾ of Earth’s entire
atmosphere including clouds and weather
 about 50% of Sun’s energy passes through
 Earth’s surface heats by conduction

– the farther from the surface you get, the cooler
it becomes
Stratosphere
above troposphere (10 km – 50 km)
 contains most of the ozone

– Absorbs ultraviolet radiation to warm area
» As you go up, you get warmer
– without ozone, the UV radiation would reach
Earth and cause health problems
Mesosphere
Extends 50km – 85km above surface
 Contains very little ozone so temperature
drops to the lowest in atmosphere

Ionosphere
part of mesosphere and thermosphere
 due to intense interaction with the sun’s
radiation
 reflects AM radio waves allowing longdistance communications possible

– static results when interaction between this
layer and radiation is too active
Thermosphere
reaches 85km – 500km
 temperatures increase rapidly
 filters out harmful X-rays and gamma rays
from the Sun

Exosphere
outermost layer
 extends outward to where space begins

– no clear boundary to space
GREENHOUSE EFFECT
Earth’s Water
70% of Earth’s surface is water
 Stored throughout the land-oceanatmosphere system in three different states

– Solid – snow, ice, glaciers
– Liquid – oceans, lakes, rivers
– Gas – water vapor

Water Cycle