All thermal radiation from a planetary surface absorbed by atmospheric greenhouse gases is re-radiated directly back toward the

The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases.
   Solar radiation at the frequencies of visible light largely passes through the atmosphere to warm the planetary surface, which then emits this energy at the lower frequencies of infrared thermal radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy to the surface and lower atmosphere. The mechanism is named after the effect of solar radiation passing through glass and warming a greenhouse, but the way it retains heat is fundamentally different as a greenhouse works by reducing airflow, isolating the warm air inside the structure so that heat is not lost by convection.
   If an ideal thermally conductive blackbody were the same distance from the Sun as the Earth is, it would have a temperature of about 5. 3 degrees Celsius. However, since the Earth reflects about 30% of the incoming sunlight, this idealized planet’s effective temperature (the temperature of a blackbody that would emit the same amount of radiation)would be about — 18 degrees Celsius. The surface temperature of this hypothetical planet is 33 degrees Celsius below Earth’s actual surface temperature of approximately 14 degrees Celsius. The mechanism that produces this difference between the actual surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect.
   Earth’s natural greenhouse effect makes life as we know it possible. However, human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming.
1. All thermal radiation from a planetary surface absorbed by atmospheric greenhouse gases is reradiated directly back toward the planet.
2. Re-radiation results in an elevation of the average surface temperature above what it would be without the gases.
3. Scarcely can solar radiation at the frequencies of visible light passes through the atmosphere.
4. Greenhouse gases can re-radiate much of the energy of infrared radiation to the surface and lower atmosphere.
5. The mechanism and the way it retains heat is of the same with that of the greenhouse.
6. If an ideal thermally conductive blackbody were the same distance from the Sun as the Earth is, it would have a temperature of about 15. 3 degrees Celsius.
7. About 30% of the incoming sunlight can be reflected by the Earth.
8. The greenhouse effect and some other factors produce the difference between the actual surface temperature and the effective temperature.
9. Earth’s natural greenhouse effect makes life impossible.
10. The burning of fossil fuels and clearing of forests have intensified the natural greenhouse effect.