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Transcript
Chapter 3 Section 2: The Atmosphere The Atmosphere Mixture of gases that surround the earth. Composition of the Atmosphere 78% nitrogen 21% Oxygen 1 % other (argon, carbon dioxide, methane, and water vapor) SOLIDS: soil, salt, ash from fire, volcanic ash, particulate matter from skin, hair, bits of clothing, pollen, bacteria, viruses Air Pressure Gravity pulls the Earth’s atmosphere towards earth Atmosphere is denser near Earth’s surface. Layers of the Atmosphere Four layers: – – – – TROPOSPHERE STRATOSPHERE MESOSPHERE THERMOSPHERE Troposphere Nearest Earth’s surface Extends to 18 km (11mi) above Earth’s surface Densest layer Temperature decreases as altitude increases. Stratosphere Extends from 18km to 50 km (31 mi). Temperatures rise as altitude increases. Ozone absorbs UV energy and warms air. Mesosphere Extends from 50 km to 80 km (49mi). Coldest layer As low as -93 degrees C. Thermosphere Farthest from earth. Nitrogen and oxygen absorb solar radiation. Temperatures above 2,000 degrees C. Lower region of thermosphere absorbs x-rays and gamma rays causing energy to be radiated as light (Northern lights) Energy in the Atmosphere Sun’s energy is transferred in 3 ways: –Radiation: transfer of heat across space in the atmosphere. –Conduction: flow of heat from warmer object to colder one. –Convection: transfer of heat by air currents. Heating of the Atmosphere Solar energy reaches earth as ELECTROMAGNETIC RADIATION (visible light, infrared radiation, ultraviolet light) Small amount of radiation penetrates, but a large amount of energy reaches earth. Excess heat is radiated back into the atmosphere. The Movement of Energy in the Atmosphere Air moves upward, downward and sideways causing earth’s weather. Warm air rises into the atmosphere, cools, and sinks back down toward earth. The process repeats causing a CONVECTION CURRENT. The Greenhouse Effect Gases trap heat near the earth and keep earth warm. Greenhouse gases: water vapor, Carbon dioxide, methane, nitrous oxide. Objectives Describe the composition of the Earth’s atmosphere Describe the layers of the Earth’s atmosphere. Explain the three mechanism’s of heat transfer in Earth’s atmosphere. Explain the greenhouse effect. http://calipsooutreach.hamptonu.edu/ atmosphere.swf