The composition of Earth’s Atmosphere and the role of the atmosphere in Earth’s weather and climate Mrs. Radef Science 7 Spring 2015 (Adapted from CCSD RPDP Content Benchmark E.8.A.4 )

* The Atmosphere * Solar Energy * Earth’s Magnetic Fields

* Absorbs the energy from the Sun * Recycles water and other chemicals to provide a moderate climate * Protects us from high-energy radiation and the frigid vacuum of space

* Earth’s atmosphere is a very thin layer of gases that surround a very large planet. * An analogy of the relative diameter of the Earth compared to the thickness of the atmosphere would be to exhale onto a billiard ball (from a pool table). * The billiard ball represents the Earth and the thin layer of condensation represents the relative thickness of its atmosphere.

* The atmosphere makes up less than one millionth of the total mass of the Earth. * Two gases make up the bulk of the atmosphere: * nitrogen (N 2 ) at 78% * oxygen (O 2 ) at 21%, * The other one percent includes water vapor, carbon dioxide (CO 2 ), argon, and trace amounts of other gases. Constant components (proportions remain the same over time and location) Nitrogen (N 2 )78.08% Oxygen (O 2 )20.95% Argon (Ar)0.93% Neon, Helium, Krypton0.00%

* The atoms and molecules that make up the various layers in the atmosphere are constantly moving in random directions. * When they strike a surface they exert a force on that surface in what we observe as pressure.

* Atmospheric pressure can be imagined as the weight of the overlying column of air. * Pressure decreases exponentially with increased altitude.

* At the top of Mt. Everest (elevation 29,028 ft.), pressure is as low as 300 mb. * There are approximately one-third as many gas molecules inhaled per breath on top of Mt. Everest as at sea level * Climbers experience severe shortness of breath the higher they go, as less oxygen is inhaled with every breath.

Earth’s atmosphere is divided into four layers: * Troposphere * Stratosphere * Mesosphere * Thermosphere * Thermosphere

* Variable components have a much greater influence on both short-term weather and long-term climate. * Variations in water vapor impact relative humidity. * CO 2, CH 4, N 2 O, and SO 2 absorb heat emitted by the Earth and thus warm the atmosphere, creating the greenhouse effect.

Variable components (amounts vary over time and location) Carbon dioxide (CO 2 )0.04% Water vapor (H 2 0)0-4% Methane (CH 4 )trace Sulfur dioxide (SO 2 )trace Ozone (O 3 )trace Nitrogen oxides (NO, NO 2 )trace

Where can you go to learn more about the Earth’s Atmosphere? * * * edu/earthguide/diagra ms/atmosphere/index.h tml edu/earthguide/diagra ms/atmosphere/index.h tml edu/earthguide/diagra ms/atmosphere/index.h tml * earn/1_3_1.htm earn/1_3_1.htm earn/1_3_1.htm