5. Composition and Structure of the Atmosphere

High altitude in the Kananaskis in the Rocky Mountains of Alberta, from which I could see Calgary from 70 km away. 2010-07-27

Lower Atmosphere

The Earth’s atmosphere consist of two main regions, the Homosphere up to about 800-100 km above the surface and the Hetrosphere above that. The Homosphere is where we live in and it has a mostly uniform chemical composition divided into 3 categories: constant gasses (Nitrogen 78%, Oxygen 21%, Argon 1%, Neon, Helium, and Hydrogen), variable gasses (Water 0-4%, Carbon Dioxide 0.04%, Methane, Nitrous Oxide, and Ozone), and impurities (aerosols, dust, smoke, and salt crystals).

Higher Atmosphere and Ionosphere

The Atmosphere’s Homosphere consists of the Troposphere (from the surface up to about 12 km), the Stratosphere (10-50 km), and the Mesophere (50-80 km). The Hetrosphere contains of the Atmosphere’s Thermosphere (80-500/1000 km) and Ionosphere’s D, E, and F regions. The Ionosphere serves as important blocker of sun-rays as well as for satellite communication.

Temperature and altitude

In the Troposphere, the temperature lowers with an average of 6.5°C per 1000m. Photo 10 above is during one of my favourite activities of the summer: trail riding in the Rockies. The view from these places is great, and was temperature change is definitely noticeable here on this 2-3 km high mountain top. GPS devices are particularly fun for these kinds of activities, because they record elevation.

Cherry Tree as part of the Earth's Nitrogen and Carbon Cycle, Lacombe, Alberta. 2011-05-29

Earth’s Cycles

The Earth’s atmosphere was formed during its early stages of development from gasses expelled by volcanoes and the hot surface of the earth. This reached a state of dynamic equilibrium, a state in which the overall composition of the earth system is in balance; however, the individual parts of the system change. There are four cycles acting between the troposphere and the lithosphere, hydrosphere, and biosphere. The hydrologic cycle circulates the water (unit 11), the oxygen cycle supplies the atmosphere with oxygen via photosynthesis and extracts it via inhaling, the nitrogen cycle involves the biosphere and extraction of nitrogen from the atmosphere to convert it into organic protein for consumption, and the carbon cycle cycles carbon dioxide from air into the oceans, to be decomposed by plankton. The carbon cycle also occurs in the biosphere (photo 11), where plants absorb carbon dioxide during photosynthesis and release it during respiration and decay.