Unit 1

1. Unit 1 Introduction to Atmospheric Science

2. 1.1 Composition • Our atmosphere • Mix of gases surrounding entire planet • Held in place by gravity • Filters out energy and materials from space • Regulates temperature, allows for water in all 3 states • Composition • Nitrogen – 78% • Oxygen – 21% • Argon – .9% • All other gases and particulants – .1%

3. 1.1 Composition

4. 1.1 Composition • Nitrogen and oxygen • Percentages are consistent to elevation of 50 miles (80 km) • Balance of destruction and production • Nitrogen removed mostly by soil bacteria, plankton • Returned by decay of plant and animal materials • Oxygen removed through chemical reaction (oxidation), organic decay, respiration • Returned through photosynthesis

5. 1.1 Composition • Water vapor • Invisible gas made of water molecules • Substance follows the water cycle • Varies greatly by location • Tropical air may be up to 4% water, arctic air may barely have any • Acts as a “greenhouse” gas, trapping Earth’s radiant energy • Latent heat • Energy stored in water molecules, gained through evaporation • Released when water condenses to liquid

6. 1.1 Composition • Carbon dioxide • Occupies .038%, but varies by location • Enters air through decay, volcanism, exhalation of animals, burning of fossil fuels • Removed through photosynthesis, dissolving into oceans, absorption by phytoplankton • Oceans may hold over 50X more CO2 than air • Past CO2 concentrations measured through Arctic and Antarctic ice cores • Evidence shows concentrations have increased 37% since the early 1800s. • Important greenhouse gas, contributes to climate change.

7. Stepped Art Fig. 1-4, p. 7

10. 1.1 Composition • Ozone (O3) • Most forms naturally in stratosphere • Provides protection from UV rays • Can be formed at surface • Chemical reactions between pollutants and sunlight create ozone • Called photochemical smog • Irritates eyes, lungs, damages plants • Common near large cities

11. 1.1 The Early Atmosphere • The Earth’s first atmosphere was composed mostly of hydrogen and helium • Evolved due to outgassing of CO2, NH3, and H2O from the cooling center of the Earth • Caused heavy rain that would form an early ocean • Lakes and oceans acted as a sink, absorbing CO2 from atmosphere • Reactions with oxygen broke down ammonia, plus volcanic eruptions produced most N2 • O2 was created almost completely through photosynthesis, first by cyanobacteria • Later, aquatic plants and algae, then terrestrial plants added O2 to today’s levels

12. 1.2 Vertical Structure of the Atmosphere • Air Pressure and Air Density • Weight = mass x gravity • Density = mass/volume • Pressure = force/area • At the Earth’s surface the pressure of the atmosphere is 14.7 lbs/in2 . • Standard sea level pressure is 1013.25millibars (mb) = 101,325 Pascals (Pa) = 29.92 in Hg • Atmospheric pressure decreases with height.

15. 1.2 Vertical Structure of the Atmosphere • Layers of the Atmosphere • Lapse rate • Change in temperature with a change in height • Typically inverse relationship, decrease in temp with increase in height • Isothermal environment • No change in temperature with height • Inversion layer • Reversal of standard lapse rate • Temps increase with height

16. 1.2 Vertical Structure of the Atmosphere • Layers of the Atmosphere • Troposphere • Decrease in temperature with height • Daily weather occurs here. • Extends up about 12 miles • Stratosphere • Ozone layer located here. • Increase in temperature caused by absorption of UV by O3 • 12 miles up to 50 miles

17. 1.2 Vertical Structure of the Atmosphere • Mesosphere • Decrease in temperature • Most meteors burn up here • 50 to 85 miles • Thermosphere • Increase in temperature • Suns strongest radiation impact. • Dramatic temperature swings day to night • 85 miles, up to the point where no gas exists

18. Stepped Art Fig. 1-11, p. 13

19. 1.2 Vertical Structure of the Atmosphere • Ionosphere • Not a true layer but an electrified region • Created when solar energy rips electrons from gas atoms • Creates ionized layers • Exists at the top of the atmosphere in the thermosphere • F,E,D layer • Sun light creates layers, D disappears at night and less interference with AM radio transmissions.

21. 1.3 Weather & Climate • Weather • Short term air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind • Climate • Long term patterns and average weather; not just magnitude but also frequency

22. 1.3 Weather & Climate • Meteorology • Study of the atmosphere and its phenomena • Aristotle 340 B.C. Meterologica, meteoros: high in air • 1843 telegraph • 1920s air masses • 1940s upper air • 1950s radar and computers • 1960s satellite

24. 1.3 Weather & Climate • Satellite’s View • Geostationary satellite • Meridians measure longitude (W-E) • Parallels measure latitude (N-S) • Weather maps: pressure cells, fronts, surface stations

26. 1.3 Weather & Climate • Weather and Climate in Our Lives • Two general reasons for studying how weather and climate impacts our lives: economic efficiency and public safety. • Clothing • Crops • Utilities • Extreme cold and heat • Tornados and hurricanes

27. 1.3 Weather & Climate • Meteorologist • Any person with a college degree in meteorology or atmospheric science; not just the TV weather person • Half of 9000 meteorologists employed by the US National Weather Service • Researchers and operational meteorologists