Download Composition of the Atmosphere

Composition of the
Atmosphere
Today’s 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
3 Major Compositional Components
1. The Fixed Gases
2. The Variable Gases
3. The Particulates (aerosols)
Lets look at each of these now
Fixed Gases
 the same ratio around the planet
• Nitrogen (N2) – 78.08% (78%)
• Oxygen (O2) – 20.95% (21%)
• Argon (Ar) – 0.93% (1%)
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Neon (Ne)
Helium (He)
Hydrogen (H)
Xenon (Xe)
very trace amounts
Properties of Fixed Gases
• Nitrogen – Inert Gas
• Oxygen – “multi-talented”
1.Organisms use in respiration
2.Used in combustion
3.A major Greenhouse gas
• Argon – Inert gas
*residual from the first atmosphere*
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
Water Vapor – 0-4%
• Clear, tasteless, odorless
• Major part of Hydrologic Cycle
• Used for energy exchange
 evaporation (absorption)
 condensation (release)
 Latent Heat Flux (can’t feel)
• Greenhouse Gas
Carbon dioxide – 365 ppm
• Oceans have about 10x more
• Product of combustion
• Ohio 7th largest producer
in the? World
• Greenhouse Gas
315 ppm in 1958
50 ppm in 42 yrs
 Goes down in summer time – leaves
Enhanced Greenhouse Effect True
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What About Global Warming?
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
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
Ozone – 0.04 ppm
• 2 types – surface & atmospheric
• Surface – BAD!!!!!! (Photo-smog)
• Stratosphere – GOOD 
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Higher concentration - 5-12 ppm
Absorbs harmful UV light from Sun
97% is found here
• Destroyed by Chlorofluorocarbons
(CFC’s) – dreaded hole in ozone layer
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
Condensation Nuclei
• Hygroscopic - “water seeking”
H2O vapor condenses readily on this
type of surface <100% humidity.
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Ocean salt is a common particle
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Not all good - sulfuric & nitric acid
Condensation Nuclei
•Hydrophobic – “water-repelling”
H2O vapor does not condense on
these surfaces even when > 100%
humidity
 Oils, gasoline, waxes are examples
