1. Atmosphere and Weather

2. Meteorology: the study of the physics, chemistry, and dynamics (movement) of the Earth’s atmosphere
Who is Stan Hatfield and Ken Pinzke

3. Atmosphere: Envelope of gases bound to the Earth by gravity

4. Weather: State of the atmosphere at a given time and place; constantly changing
Weather is described by variables such as:
-- Temperature
-- Wind Speed
--Wind Direction
-- Pressure
-- Precipitation
-- Cloud Cover

5. Climate - is a pattern of weather over a long period of time
Climate - is a pattern of weather over a long period of time. It is affected by the distance from the equator and determines the type of life that can be found in an area.

6. Weather or Climate??? Cumulus clouds are covering the entire sky.
The summers here are warm and humid.
At 3:00 p.m, winds were blowing from the NW at 10 mph.
Chicago has cold and windy winters.
Chicago is experiencing a polar vortex.

7. Origin of the atmosphere
The original atmosphere
Probably made up of hydrogen and helium.
Original atmosphere stripped away by the solar wind
H and He are very light
Hydrogen and helium have the smallest atoms by mass.
Thus the current atmosphere is considered a secondary atmosphere

8. The secondary atmosphere
Formed from degassing of volcanoes
Gasses emitted probably similar to the gasses emitted by volcanoes today.
H2O (water), 50-60%
CO2 (carbon dioxide), 24%
SO2 (sulfur dioxide), 13%
CO (carbon monoxide),
S2 (sulfur),
Cl2 (chlorine),
N2 (nitrogen),
H2 (hydrogen),
NH3 (ammonia) and
CH4 (methane)
VERY LITTLE O2

9. Modern atmosphere Nitrogen (N2) - 78%, Oxygen (O2) - 21%,
Carbon Dioxide (CO2) %,
Where did all the oxygen come from?

10. Miller – Urey Experiment
The Miller-Urey experiment was a chemical experiment that simulated the conditions thought at the time to be present on the early Earth. It tested the chemical origin of life.
Amino acids from:
Ammonia
Methane
Water Vapor
(if these were the gasses of the early atmosphere)

11. Modern atmosphere Life changes the atmosphere
With the evolution of life, the first cellular organisms began to use the gasses in the early atmosphere
NH3 – ammonia,
CH4 – methane,
H2O – water for energy.
Photosynthetic organisms evolve. (cyanobacteria)
These organisms use CO2 and produce oxygen (O2) as a waste product.

12. Modern atmosphere Where did the O2 come from?
Produced by photosynthetic life.
The oxygen eventually helped to form the Ozone layer, which allowed for more diverse biological presence
Where did the CO2 and CH4 go?
Dissolves in water in the oceans
Used by life in photosynthesis (CO2) and temporarily locked away in the Earth when plants and micro-organisms die.
Stored in permafrost and hydro-thermal vents

13. Air Pressure
Can you feel it?

14. Atmospheric Structure
 The atmosphere rapidly thins as you travel away from Earth until there are too few gas molecules to detect.
Pressure Changes
• Atmospheric pressure is simply the weight of the air above.
As you move UP through the atmosphere, air pressure decreases.

15.  Pressure changes due to gravity

16. Air Pressure
Air pressure is the measure of the force with which air molecules push on a surface.
Air Pressure is GREATEST at the surface of Earth because there is more of the atmosphere above you to push down on you.

17. Air Pressure is dependant on DENSITY
More dense air will have a higher air pressure- there are more air molecules in a given space to push down on you
Less dense air will have a lower air pressure- there are fewer air molecules to push down on you.
More Dense= more particles to push down on you
Less Dense= fewer particles to push down on you

18. Impact of Temperature on Air Pressure
Warm air is less dense than cold air. Therefore, warm air has a lower air pressure and cold air has a higher air pressure.
Warm Air
Cold Air

19. Observing Weather Gizmo (finish)