2. Composition of the Atmosphere

3. Today’s Objectives 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 Students will be able to:

4. 3 Major Compositional Components 1. The Fixed Gases 2. The Variable Gases 3. The Particulates (aerosols) Lets look at each of these now

5. Nitrogen (N 2 ) – Oxygen (O 2 ) – Argon (Ar) – Neon (Ne) Helium (He) Hydrogen (H) Xenon (Xe) Fixed Gases very trace amounts 78.08% (78%) 20.95% (21%) 0.93% (1%)  the same ratio around the planet

6. Properties of Fixed Gases Nitrogen – Inert Gas Oxygen – “multi-talented” respiration 1.Organisms use in respiration combustion 2.Used in combustion Greenhouse gas 3.A major Greenhouse gas Argon – Inert gas *residual from the first atmosphere*

7. Variable Gases H 2 O Vapor – 0-4% Carbon dioxide (CO 2 ) – 0.036% (365 ppm) Methane (CH 4 ) – 1.7 ppm Nitrous oxide (N 2 O) – 0.3 ppm Ozone (O 3 ) – 0.04 ppm

8. 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

9. Oceans have about 10x more Product of combustion Ohio 7 th largest producer in the? Greenhouse Gas  315 ppm in 1958 50 ppm in 42 yrs  Goes down in summer time – leaves  Enhanced Greenhouse Effect Carbon dioxide – 365 ppm World True What About Global Warming?

10. 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 FARTS…eww!!

11. 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

12. Ozone – 0.04 ppm 2 types – surface & atmospheric BAD!!!!!! Surface – BAD!!!!!! (Photo-smog) GOOD Stratosphere – GOOD  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

13. 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 H 2 O to condense on The nuclei for H 2 O to condense on

14. Condensation Nuclei Hygroscopic Hygroscopic - “water seeking”  H 2 O vapor condenses readily on this type of surface <100% humidity.  Ocean salt is a common particle  Not all good - sulfuric & nitric acid

15. Condensation Nuclei HydrophobicHydrophobic – “water-repelling”  H 2 O vapor does not condense on these surfaces even when > 100% humidity  Oils, gasoline, waxes are examples