Earth’s Atmosphere

Chapter 1:  Earth’s Changing Atmosphere

Section 1.1:  Earth’s atmosphere supports life.


I.  Vocabulary

         A.  atmosphere-  a protective layer of air that surrounds the Earth and supports life

         B.  altitude-  height or distance above sea level

         C.  density-  the amount of mass in a  given amount of a substance

         D.  cycle-  processes that repeat over and over


II.  The atmosphere supports life and protects it

A.  Gases transport energy and keep Earth warm

B.    Without the atmosphere—no oceans, no life

C.    Very thin--  if the Earth were a peach, the atmosphere would be the fuzz


III.  Characteristics of the atmosphere

A.  As altitude increases, the air gets  thinner (less dense)

B.     So, density of air decreases as you travel upward

C.     Where jets fly the air contains 1/10 the mass of the air at sea level

D.     If you took a deep breath, the air would fill your lungs but there would be fewer gases in it (baseball ex.)

E.     No definite top to the atmosphere, but 300 miles above Earth’s surface is considered outer space

F.     More than 99% of the atmosphere’s mass is in the lowest 20 miles


IV.  Materials in the atmosphere

A.  Most materials are gases

B.     Also contains:  dust, sea salt, water droplets

C.     Breakdown of gases in the air







Promotes plant growth, makes up chemicals in living things



Necessary for animals and plants to perform life processes



Plants use CO2 to make food, Ar is used to destroy tumors


(This varies)


Important part of the water cycle, global warming


V.  Natural cycles modify the atmosphere

         A.  The Carbon Cycle

                  1.  CO2 and O2 constantly circulate, or cycle, among plants, animals and the atmosphere

                  2.  Examples

                           a.  Animals inhale air, use O2, and exhale air with less O2 and more CO2 and water vapor

                           b.  Plants take in CO2 and release O2 as they make food (photosynthesis)

         B.  The Nitrogen Cycle

                  1.  Different forms of N2 cycle among the atmosphere, the soil, and living organisms

                  2.  Examples

                           a.  Tiny organisms remove N2 from the air and turn it into other chemicals, which enter the soil

b.  Plants and animals use solids and liquids that contain N2, which returns to the soil when they die or decay

c.  Soil slowly releases N2 back into the air as a gas

         C.  The Water Cycle

                  1.  Different forms of H2O cycle between Earth’s surface and atmosphere

                  2.  Examples

                           a.  Liquid H2O from oceans/lakes changes into gas and enters atmosphere

                           b.  Plants release H2O vapor from their leaves

                           c.  Liquid H2O falls from the atmosphere as precipitation


VI.  Sudden changes alter the atmosphere

A.  Volcanic eruptions

1.  Volcanic gases and ash can be shot into the stratosphere, blocking out sunlight and decreasing temperatures globally for decades

B.     Forest fires          

                  1.  When trees burn, the C that makes up each tree combines with O2 to form CO2

                  2.  Wood ash also fills the air

         C.    Dust storms

                  1.  Wind, water, or drought can loosen soil. 

                   2.  Powerful windstorms may raise clouds of eroded soil