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The Atmosphere The Atmosphere 1. Layers of the Atmosphere 2. Air Pressure 3. Transfer of Heat Energy 4. Earth-Atmosphere Energy Balance 5. Hydrologic Cycle The gases that makeup the Atmosphere Layers of the Atmosphere • Troposphere - Lowest Layer This is where we live 8 to 12 miles in height Weather occurs Temp decreases with height • Stratosphere - Second lowest layer - Temp increases with height - Ozone (03) layer - Absorbs most of the damaging ultraviolet sunlight (UV-B) • Mesosphere - From ~30 to 53 miles up - Temp decreases - Majority of meteors burn up • Thermosphere - Upper atmosphere 53 to ~430 miles up - Very few molecules Still would feel cold Ozone Layer Troposphere contains about 75% of the mass the earth’s air, but is only about 17km thick. Most weather events occur here. It’s composition is uniform due to mixing caused by winds. Temperatures drop with altitude. The sharp boundary in temperature at the tropopause limits mixing with upper layers Stratosphere extends to about 50km thick. Similar in composition to the troposphere except in two ways. It contains1000 times less water and is 1000 times higher in ozone. Ozone is produced by lightning and solar irradiation of oxygen molecules. The Stratosphere is relatively calm, volcanic ash or human caused pollution can remain in suspension in the stratosphere for many years. Air Pressure • Density of Molecules decreases with height. • Although the atmosphere goes up to 184 miles, half of the atmosphere is in the first 18,000 feet or 3.4 miles. • Less molecules (same composition) higher up makes it is harder to breath than at sea level. • Air Pressure is converted to Sea Level Pressure to observe surface low and high pressures. (otherwise the Rocky Mts. would be always be low pressure and the oceans would be areas of high pressure). • Pressure also dependent upon Temperature (We will perform an experiment on this) Barometers Draw Isotherms. 26.64 -- 902 Hurricane Katrina (2005) Go with the Flow 1. Air flows from high to low pressure. 2. The air blown between the cans created an area of low pressure between the cans and induced high pressure surrounding the cans. This caused the cans to move from high to low pressure. This is known as Bernoulli’s Principle. Earth-Atmosphere Energy Balance The Effects of Clouds • Nighttime: clouds keep the earth warmer • Daytime: clouds keep the earth cooler Nitrogen and Oxygen gas can neither absorb or emit thermal radiation. It is Water vapor, carbon dioxide, and some other minor gases which absorb long-wave thermal radiation leaving the surface. This is why the average surface temperature is 15C instead of -6C which it should be it balanced. 1. Solar radiation 2. Radiation from greenhouse gases 3. Radiation scattered by atmosphere. Greenhouse Effect Prevents heat loss mainly from convection (air movement carrying away the heat) Questions A sunburn is caused by which method of heat transfer: A.) Radiation B.) Convection C.) Conduction D.) Visible Light Answer: Radiation Questions The layer of the atmosphere where most of the world’s weather occurs is: A.) Thermosphere B.) Stratosphere C.) Troposphere D.) Hemisphere E.) Mesosphere Answer: Troposphere Questions At night, temperatures will normally be cooler under cloudy skies than under clear skies. A.) True B.) False Answer: False Questions The brief cloud that forms when you exhale on a cold winter day was formed because of: A.) Precipitation B.) Convection C.) Evaporation D.) Condensation E.) Runoff Answer: Condensation Questions The hydrologic cycle is: A.) Convection, conduction, condensation, Radiation B.) Rain, Sunshine, Condensation, Flood C.) Evaporation, Transpiration, Condensation, Precipitation, Runoff Answer: C Questions If you feel the heat in the handle of a cooking pot, that heat was transferred to the handle by: A.) Convection B.) Conduction C.) Radiation Answer: Conduction Questions It is _____ to breath on top of a mountain than at sea level because there are ______ oxygen molecules at the summit. A.) easier / more B.) harder / more C.) easier / less D.) harder / less Answer: harder / less
