The Atmosphere Honors Biology Chapter 3

Definition Layer of gases surrounding the geosphere Includes nitrogen, oxygen, carbon dioxide, and smaller amounts of others Constantly changing and evolving Insulates life on earth –Radiation –Heat –objects

Composition 78% Nitrogen, 21% Oxygen, and 1% of many other gaseous elements and compounds (argon, CO 2, methane, water vapor Atmospheric dust (soil, salt, ash, skin, hair, clothing bits, pollen, tire remnants, viruses, bacteria, and aerosols

Gases

Particulates

Air Pressure Molecules pulled by gravity Denser near surface (30km) Breathing difficult with altitude

Atmosphere Regions Troposphere – surface to 18km; weather occurs here; densest layer; temperature decreases with altitude

Atmosphere Regions Stratosphere – km; temperatures rise with altitude because ozone layer absorbs UV rays and heats the thin air

Atmosphere Regions Mesosphere – km; less dense; coldest region (-93 degrees Celcius)

Atmosphere Regions Thermosphere – above 80km; warmest region of atmosphere because oxygen/nitrogen absorb solar radiation (but don’t transfer it because of thinness of air

Atmosphere Regions Thermosphere – the “ionosphere” is located here; absorbed radiation creates ions that radiate energy as light, as in the……..

Energy Transfer Radiation – the transfer of energy across space and in the atmosphere Conduction – flow of heat from warmer to cooler object when they are in direct contact Convection – transfer of heat by flowing currents (of air when referring to the atmosphere)

Air Movement

Greenhouse Effect Atmosphere allows sunlight to enter Light changes to heat when striking objects/surfaces Heat energy is absorbed by “greenhouse gases” in the atmosphere Atmosphere is warmed

Good because it provides heated atmosphere for life as we know it Bad when it is multiplied by man’s addition of greenhouse gases to atmosphere

Global Warming? Sun’s cyclical output of energy Man’s effects on greenhouse effect What does it all mean?