Composition of the Atmosphere

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Composition of the Atmosphere
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Todays Objectives
Students will be able to

1. Distinguish gases between fixed, variable, and
   particulate
2. Identify the Greenhouse gases
3. Describe each type of gas
4. Discuss the role of each gas in the atmosphere

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3 Major Compositional Components

1. The Fixed Gases
2. The Variable Gases
3. The Particulates (aerosols)

Lets look at each of these now
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Fixed Gases

• Nitrogen (N2)
• Oxygen (O2)
• Argon (Ar)
• Neon (Ne)
• Helium (He)
• Hydrogen (H)
• Xenon (Xe)

• the same ratio around the planet

78.08 (78)
20.95 (21)
0.93 (1)
very trace amounts
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Properties of Fixed Gases

• Nitrogen Inert Gas
• Oxygen multi-talented
• Organisms use in respiration
• Used in combustion
• A major Greenhouse gas
• Argon Inert gas
• residual from the first atmosphere

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Variable Gases

• H2O Vapor 0-4
• Carbon dioxide (CO2) 0.036
• (365 ppm)
• Methane (CH4) 1.7 ppm
• Nitrous oxide (N2O) 0.3 ppm
• Ozone (O3) 0.04 ppm

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Water Vapor 0-4

• Clear, tasteless, odorless
• Major part of Hydrologic Cycle
• Used for energy exchange
• evaporation (absorption)
• condensation (release)
• Latent Heat Flux (cant feel)
• Greenhouse Gas

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Carbon dioxide 365 ppm

• Oceans have about 10x more
• Product of combustion
• Ohio 7th largest producer
• in the?
• Greenhouse Gas
• 315 ppm in 1958 50 ppm in 42 yrs
• Goes down in summer time leaves
• Enhanced Greenhouse Effect

World
True
What About Global Warming?
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Methane 1.7 ppm

• Greenhouse Gas
• Fastest growing component
• 0.5 per year increase
• Most potent
• Where is its origin?

1. Breakdown of plant material by bacteria in rice
   paddies
2. Termite activity
3. Biochemical reactions in stomachs of cows

COW FARTSeww!!
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Nitrous Oxide 0.04 ppm

• Commonly known as laughing gas
• Increasing 0.25 per year
• Greenhouse Gas
• Forms in soil through a chemical process
  involving bacteria and certain microbes.
  (mutualism)
• Ultraviolet (UV) light destroys it

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Ozone 0.04 ppm

• 2 types surface atmospheric
• Surface BAD!!!!!! (Photo-smog)
• Stratosphere GOOD ?
• Higher concentration - 5-12 ppm
• Absorbs harmful UV light from Sun
• 97 is found here
• Destroyed by Chlorofluorocarbons
• (CFCs) dreaded hole in ozone layer

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Particulates (aerosols)

• Dust, sand, soil from erosion
• Salt particles from the ocean
• Smoke and ash from forest fires
• Ash and gas from volcanism
• Pollution from who else MAN!

• The nuclei for H2O to condense on

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Condensation Nuclei

• Hygroscopic - water seeking
• H2O vapor condenses readily on this type of
  surface lt100 humidity.
• Ocean salt is a common particle
• Not all good - sulfuric nitric acid

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Condensation Nuclei

• Hydrophobic water-repelling
• H2O vapor does not condense on these surfaces
  even when gt 100 humidity
• Oils, gasoline, waxes are examples