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Chapter 22 The Atmosphere. Composition of the Atmosphere. Permanent: Nitrogen-78% Oxygen-21%, Others - 1% Variable: Water vapor (H 2 O) Carbon dioxide (CO 2 ) Ozone (O 3 ) Particulates. Composition of the Atmosphere. 99 % permanent gases and 1% variable (trace) gases.
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Composition of the Atmosphere • Permanent: • Nitrogen-78% • Oxygen-21%, • Others - 1% • Variable: • Water vapor (H2O) • Carbon dioxide (CO2) • Ozone (O3) • Particulates
99% permanentgases and 1% variable(trace) gases. • Permanent gases - constant concentration with time & space. • Variable gases - varying concentration depending upon where/when you are. • All weather and climate are associated the 1% variable gases.
Parts of Atmosphere important to weather 1. Water Vapor - more in warmer locations - forms clouds and drives weather - absorbs heat to keep earth warm
2. Carbon Dioxide • Absorbs energy from the earth
3. Ozone • Ozone high in the atmosphere is good • Absorbs harmful UV rays • Ozone here is formed naturally
- Ozone low in the atmosphere is bad • creates smog • made by humans
Particulates - Volcanic dust, ash from fires, pollen - Absorb water and helps to form clouds - Absorbs/reflects sunlight
Atmospheric Pressure The weight of the air above a point Decreases with altitude Also changes with temperature and amount of water vapor in the air Measured with a barometer Standard Atmospheric Pressure = 1 atm or 760 mm of mercury or 1000mb
Atmospheric pressure variation with altitude
Measuring Pressure Mercurial Barometer -Tube filled with mercury -air pressure pushes on mercury from bottom -causes mercury to rise and fall
Aneroid Barometer • Metal expands and contracts with changes in pressure • Causes pointer to move so pressure can be read
Barograph • Recording aneroid barometer • Keeps track of pressure over several days
Troposphere • Weather Sphere • Bottom Layer • Temperature decreases with height • Most clouds • Most water vapor • Most airplanes fly here
Stratosphere • Ozone Layer • Increase Temp with height because ozone absorbs UV
Mesosphere • Temperature decreases to coldest point at the mesopause (-90⁰C) • Many meteors burn up in this layer.
Thermosphere • Air is very thin. • Temperature increases due to absorption of solar energy by nitrogen and oxygen • Satellites orbit here
Ionosphere – part of the thermosphere • Electrically charged layer • AM radio waves reflect off of here • Causes auroras
Create your OWN mnemonic phrase to memorize the order of the five layers. For example: T = Troposphere = Terribly S = Strostosphere = Scary M = Mesosphere = Monsters T = Thermosphere = Terrorize E = Exosphere = Earth