Greenhouse Misconceptions
by Tom Kondis
November 2008
As a retired chemist with experience in absorption and emission spectroscopy, I've noticed basic errors in arguments
promoted by speculators of man-made climate change and propagated in the popular media. Specifically, they've
incorrectly compared absorption behavior of carbon dioxide gas to a functioning greenhouse, erroneously equated infrared
(IR) radiation to greenhouse-energizing radiation from the sun, and distorted textbook science.
Their misconceptions result from confusing common usage of 'absorption' for its scientific definition. In the scientific sense, absorption occurs when a quantum of radiant energy (a photon) coincides with an allowed transition to a higher energy state of the atom or molecule absorbing it. Unlike water sopped up, unchanged, by a sponge, the absorbed photon disappears as the radiant energy assumes kinetic status, allowing the absorber to move, vibrate, shake and bump neighboring things. It's a natural transfer of radiant to kinetic energy. The subsequent diversified kinetic behavior is an energy dissipation process mandated by the second law of thermodynamics, which is popularly stated as the spontaneous downhill flow of energy, high to low or hot to cold.
Emission is the reverse transfer of kinetic to radiant energy. A kinetically excited atom or molecule may rid itself of excess energy by emitting an appropriate photon and reverting to its ground energy state. Nature decides which transitions are allowed or forbidden, and spectroscopists depend on their precise values to identify the chemical elements, ions and compounds which participate in these energy exchanges.
Besides overlooking the second law's role in the absorption process, the climate speculators also ignore another proven textbook principle. The Stefan-Boltzmann Law describes the exponential proportionality between the total intensity of emitted radiation and the emitter's temperature. Both principles are essential to understanding how a greenhouse operates, the enormous energy differential between IR radiation and the solar radiation which heats one, and why a greenhouse-carbon dioxide analogy is fallacious.
Stefan-Boltzmann confirms that, at approximately 10,000 degrees Fahrenheit, the sun's surface emits photons whose peak intensity is in the visible region of the electromagnetic spectrum with considerable overlap into the hotter ultraviolet (UV) and colder IR directions of the spectrum. By contrast, the earth, whose surface temperature is only about 100 degrees Fahrenheit, emits photons at a significantly lower peak intensity in the IR region of the spectrum; there's no overlap into the visible (nor UV) region. Our metabolic process, for example, makes humans (and polar bears) excellent IR emitters.
Fundamentally, a greenhouse is a physical structure that traps hot air. Of the solar radiation striking earth, the visible and some bordering UV is admitted into a greenhouse; glass absorbs IR and the remaining UV photons, denying them entry. Some transmitted photons, free to travel in either direction, may be reflected out; they're not trapped. The majority, absorbed by opaque surfaces, disappear as they dissipate the sun's surface energy inside the greenhouse to cause convective heating of the confined atmosphere (primarily nitrogen and oxygen). Without corresponding opportunity to escape, the hot air remains trapped. Cooler IR photons emitted during dissipation of the sun's heat, either inside or outside a greenhouse, are in thermal equilibrium with the earth's surface; they're a consequence, not the initiator, of greenhouse heating.
Water vapor, liquid water, ice and snow, far more abundant than carbon dioxide, are all efficient IR absorbers participating in earth's thermal balance. Nevertheless, speculators blame IR absorption by carbon dioxide, approximately 0.035% of the atmosphere, for changing our climate. They haven't verified their unique viewpoint by utilizing IR radiation, synthetic gas mixtures and temperature measurements independent from the influences of poorly understood and incompletely considered natural forces that do control earth's climate and weather. Their arguments lack substance and veracity.
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