The Atmosphere Aim: How are the layers of the atmosphere organized?

1. Composition of Atmosphere Nitrogen is most abundant (78%) Oxygen is second most abundant (21%) Remaining 1% is made of traces gases

2. Layers of the atmosphere atm is divided according to temperature differences Contains 4 main layers

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 What happens to water vapor concentration as altitude increases?  What happens to air pressure as altitude increases?  What happens to temperature as altitude increases?

Troposphere A. Troposphere Tropo- changing Closest to Earth’s surface Weather occurs here Contains most of the water vapor and CO 2 in atm Temperature decreases as altitude increases TropopauseTropopause: boundary – temp stops decreasing –Altitude varies with latitude and season

Stratosphere B. Stratosphere Strato- layer Extends to altitude of about 50 km Contains ozone layer Temp increases as altitude increases –Direct absorption of solar energy by ozone Stratopause: boundary –highest temp

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Mesosphere C. Mesosphere Meso- middle Extends to about 80 km Temp decreases as altitude increases Coldest layer of atm Meteors burn up in this layer Mesopause: boundary –Marked by an increase in temp

If the Mesosphere is the coldest layer of the atmosophere, why do meteors burn up there?

Thermosphere D. Thermosphere Thermo- heat Temp increases steadily with altitude Nitrogen and oxygen absorb solar energy Air is very thin, temp 2,000 o C Contains ionosphere –Layer where gases absorb solar rays and lose electrons, forming ions and free electrons –Used to reflect radio waves back to Earth –Charged particles create aurora borealis Exosphere: area where atm blends into space

Gravity pulls gases toward Earth’s center 3. Atmospheric Pressure

Most of the atm mass is found in troposphere As altitude increases, amount of air molecules decrease  less air pressure Avg 14.7lbs of air pressure at sea level

Summary 1) What happens to the amount of water vapor as altitude increases above sea level? 2) State the relationship between altitude and air pressure. 3) Which layer does weather occur? Why?

Pod cast: Our changing atmosphereOur changing atmosphere