Heat Cannot Be Trapped Because It Radiates Away Constantly
Obviously, the air cools at night. Why would some of the heat be trapped while the rest cools?
Most heat gets into the atmosphere through conduction, convection (wind blowing over the surface) and evaporation. Why doesn't it get trapped? Some scientists used to claim that greenhouse gases are the only means for getting heat into the atmosphere. They stopped saying that recently, but activists didn't notice.
When a molecule of carbon dioxide absorbs radiation, it re-emits the radiation in femto seconds (a typical average of 83 femto seconds). The time can be calculated based on wavelength of the radiation. Each wave of emitted radiation is a vibration back and forth by the molecule emitting it.
A wave of black body infrared radiation being emitted is stronger than a wave of fingerprint radiation being absorbed, which means radiation is emitted as fast as it is absorbed. All matter emits black body infrared radiation constantly. Otherwise, there would be nothing for carbon dioxide to absorb.
Carbon dioxide absorbs 8% of the black body bandwidth, which means it is 8% as strong as the black body radiation being emitted. This is because the "fingerprint radiation" being absorbed by carbon dioxide only influences part of the molecule causing bonds to be stretched, while black body radiation is emitted by the entire molecule as it vibrates between the molecules around it. This means energy absorbed by carbon dioxide is re-emitted as block body radiation as fast as it is absorbed.
This is why "heat trapping gas" had to be contrived as a propaganda statement. If the heat isn't trapped, it can't be spread to the 2,500 molecules around it.
The amount of black body radiation emitted by all matter is based on the temperature as indicated by the Stefan-Boltzmann constant.
As molecules vibrate, they impart some kinetic energy to the molecules which they strike, and they emit some energy as radiation. The exact ratio varies with conditions and is too complex to determine exactly, but it can be guessed at for a rough estimate.
This image shows how energy is re-distributed when radiation is absorbed by carbon dioxide.
When a molecule of CO2 in the atmosphere absorbs fingerprint radiation (the only thing in question) it increases in vibratory motion, which is heat. As it bumps into surrounding molecules (mostly nitrogen gas), it imparts some motion, which reduces its own motion, while increasing the motion of the other molecule. This bumping goes from molecule to molecule, as the energy spreads through the atmosphere.
The vibrating motion of molecules sends out waves of infrared radiation. As the molecular motion decreases, the intensity of the radiation and its frequency get lower.
The amount of such bumping and re-emitting that must occur to lose the energy gained by absorption depends upon how strong the radiation is that is absorbed, which is determined by the temperature of the emitting molecules. Emissions from the surface of the earth into the atmosphere would go from warmer to colder. For short distances in the atmosphere, the emitting temperature would be about the same as the absorbing temperature.
Absorbed radiation (fingerprint radiation) is weaker than emitted radiation (black body radiation), because 8% of black body radiation is fingerprint radiation absorbed by CO2. In the top image, 8% of the horizontal distance is CO2, as tested during the early fifties.
When temperatures are equal for emission and absorption, radiation absorbed by carbon dioxide would be re-emitted within the time required for five wavelengths or bump cycles. Five times 83 femto seconds is 415 femto seconds. But most emission occurs during the first bump, which means the total is closer to 83 than 415 femto seconds.
Why five cycles? CO2 absorbs finger print radiation in three peaks, the strongest one at 15 microns of wavelength. It then emits the energy as black body radiation due to the vibration of the molecules. Weak radiation is absorbed and stronger radiation is emitted, except that kinetic energy (heat, when averaged) is also being imparted to nearby molecules at the same time. Those molecules also emit radiation. By the time five bumps occur, the initial radiation energy would be re-emitted.
Since each CO2 molecule in the atmosphere is surrounded by 2,500 air molecules, it would have to be 2,500°C to heat the surrounding molecules to an average temperature of 1°C, which is absurd. The CO2 molecules cannot be much different in temperature than surrounding molecules.
What would actually occur is that the CO2 would only be heated trillionths of a degree centigrade, and no greenhouse effect would occur. Why trillionths of a degree? Because radiation is extremely weak. It's energy is dissipated in femto seconds. The energy cannot build up. This effect rides on top of normal temperatures, which are mostly produced through conduction, convection and evaporation.
It is equilibrium that determines the temperature of the atmosphere, which is independent of how the heat gets into the atmosphere. Equilibrium means the temperature builds up until the amount of radiation into space equals the amount of radiation entering from the sun. Some persons say greenhouse gases shift the equilibrium temperature upward, but this is where the trillionths of a degree enter in. Radiation would escape into space almost as fast after striking a few CO2 molecules.