The major atmospheric gases, nitrogen and oxygen, each have unique properties vital to most living organisms and they alone do not explain our comfortable average temperatures, because they are essentially ‘transparent’ to long-wave electromagnetic radiation.
The so-called greenhouse gases have a temperature stabilising effect because, they intercept radiated heat energy and radiate it out again in all directions. In fact, it is estimated that the average temperature on earth without this ‘greenhouse effect’ would be around -18°C.
Some 51% of the radiant energy over a range of wavelengths that arrives from the sun is absorbed by the oceans, land and surface vegetation, where it is converted into heat – raising the ambient temperature.
This energy is re-radiated but as longer wavelength, invisible infrared rays that cannot escape through the atmosphere, because it is absorbed by certain gas molecules including: water vapour (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozone (O3).
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