Philosophy of Science
Science is based on the concept that the natural universe behaves in a consistent and predictable pattern
Hypothesis or Theory?
The system used to answer questions scientifically - through observations and experimentation
1. Definition of the Problem
2. Literature Search
4. Experimentation and/or Observation
6. Testing of the Theory
7. Publication of Theory
8. Verification by Other Researchers
Studying The Atmosphere
A System is:
1) a regularly interacting or independent group of items forming a unified whole.
2) a group of related interacting bodies under the influence of related forces.
Geosphere: the solid Earth; earth materials; minerals, rocks, metals (Geology, Geography, Geoscience)
Atmosphere: the gaseous Earth (Meteorology, Climatology)
Hydrosphere: the water Earth (Hydrology, Oceanography)
Biosphere: life on Earth (Biology, Life Sciences)
Composition of the Earth's Atmosphere
|Major Components||Minor Components|
|N2 (nitrogen)||78.084%||Ne (neon)||0.0018%|
|O2 (oxygen)||20.946%||He (helium)||0.0005%|
|H2O (water)||0-5%||Kr (krypton)||0.0003%|
|Ar (argon)||0.934%||CH4 (methane)||0.00017%|
|CO2 (carbon dioxide)||0.038%||H2 (hydrogen)||0.00006%|
|N2O (nitrous oxide)||0.00003%|
|Total Mass||5.136x1026 g||particles (dust and soot)||0.000001%|
|Total Mass||5.7x1016 tons||CFC (chlorofluorocarbons)||0.00000001%|
Origin of the Atmosphere
Linked with the origin of the Earth
The present atmosphere is not the result of accumulation of solar nebula gases
Differentiation formed the atmosphere
More dense material sank toward the Earth's center, while less dense material rose towards the surface.
This less dense material includes gases: out gassing (out gassing occurs at volcanoes)
Original Earth atmosphere:
From where did the Oxygen come?
Photosynthesis is the process in which the plant takes in CO2 from the atmosphere plus water and releases O2 as a waste product.
Photosynthesis evolved in blue-green algae approx. 3.5 billion years ago
Small amounts of O2 into the oceans and atmosphere at this time
At approx. 1.5 billion years ago, organisms evolve that utilize oxygen
1.5 b.y. - 1% atmospheric oxygen present.
550 million years ago - approx. 3% atmospheric oxygen present.
450 million years ago - approx. 10% atmospheric oxygen present.
During the Pennsylvanian Period, 320-286 million years ago, oxygen levels may have exceeded present levels: 23% - 28% atmospheric oxygen
Evidence for high levels of O2?
Changes in the Composition of the AtmosphereWhat are some of the factors which change the amounts of the various components?
Oxygen - O2
Carbon Dioxide - CO2
Water - H2O
Methane - CH4
Ozone - O3
Produced naturally in the atmosphere as O2 + O+ combines to form O3
Ozone depletion occurs naturally due to: Ultraviolet radiation, nitrous oxide reactions, oxidation reactions, chemical reactions from industrial waste, CFCs
Formation of Ozone:
Destruction of Ozone:
Destruction of Ozone by CFC:
Montreal Protocol on Substance that Deplete the Ozone Layer
Large Scale Structure of the Atmosphere
For the lower portion of the atmosphere, increased elevation means decreased temperature.
Temperature decreases at a constant rate known as the Lapse Rate.
For every 1000 meters of altitude, temperature decreases 6.4°C.
0-12 km (9 to 16 km)
Lower atmosphere - Contains most of the weather that affects us - significant amounts of water - abundant aerosols (fine liquid and solid particles)
approx. 12 km - varies in elevation with seasons and latitude
Level at which temperature stops decreasing and begins increasing
14 - ~50 km
High altitude air mass - low water and dust content
Ozone layer is found in this layer
~50 - 80 km
Temperature decreases with higher elevations
Coldest temperatures in the atmosphere
Extremely rarified air
Temperatures increase to more than 1000°C
Due to absorption of shortwave, high energy solar radiation
60 - 400 km
Electrically charged layer of ionized Nitrogen and Oxygen
Created by shortwave solar radiation
Solar radiation and charged particles of the solar wind follow the Earth's magnetic force lines and enter the atmosphere at the poles.