1.0 Introduction: What on Earth Is the "Greenhouse Effect"?
Confusion and Lack of Thermodynamic DefinitionAlthough the "Greenhouse Effect" is of crucial importance to modern climatology and is the putative cornerstone of the Anthropogenic Global Warming hypothesis, it lacks clear thermodynamic definition. This forecasts the likelihood that the name is misapplied. Even general descriptions of the "Greenhouse Effect" may seem confused when compared to one another. In the first year university geology text by Press & Siever (1982, p. 312) we read:
"The atmosphere is relatively transparent to the incoming visible rays of the Sun. Much of that radiation is absorbed at the Earth's surface and then reemitted as infrared, invisible long-wave rays that radiate back away from the surface (Fig. 12-14). The atmosphere, however, is relatively opaque and impermeable to infrared rays because of the combined effect of clouds and carbon dioxide, which strongly absorbs the radiation instead of allowing it to escape into space. This absorbed radiation heats the atmosphere, which radiates heat back to the Earth's surface. This is called the 'greenhouse effect' by analogy to the warming of greenhouses, whose glass is the barrier to heat loss."This explanation is fundamentally confusing because it is seemingly contradictory, as impermeable
"The incoming solar radiation that the earth absorbs is re-emitted in the form of so-called infra-red radiation - this is where the vital 'greenhouse effect' begins. Because of the chemical structure of the greenhouse gases in the atmosphere, they absorb the infra-red radiation from the Earth, and then emit it, into space and back into the atmosphere. The atmospheric re-emission helps heat the surface of the Earth - as well as the lower atmosphere - and keeps us warm."This explanation describes the "Greenhouse Effect" as "vital", perhaps because, as Whitaker points out, it warms the earth's surface. Wishart (2009, p. 24) explains that this "Greenhouse Effect" is useful for a completely different reason:
"The Moon is another excellent example of what happens with no greenhouse effect. During the lunar day, average surface temperatures reach 107ºC, while the lunar night sees temperatures drop from boiling point to 153 degrees below zero. No greenhouse gases mean there's no way to smooth out temperatures on the moon. On Earth, greenhouse gases filter some of the sunlight hitting the surface and reflect some of the heat back out into space, meaning the days are cooler, but conversely the gases insulate the planet at night, preventing a lot of the heat from escaping."In Wishart's explanation above, the Greenhouse Effect" is no longer a warming mechanism but a thermal buffer that moderates the extremes of temperature.