Old Rocks
Diamond Member
You were told they can measure the light absorbed by a gas and determine the absorption spectrum. If it doesn't absorb IR it isn't a greenhouse gas. You were told they can measure the sunlight striking a planet too, the amount of light the planet gives off and it's temperature. Without the greenhouse effect, the planet doesn't warm much.
Yes dubya, the absorption spectra of so called greenhouse gasses to tell us that they absorb IR. What you don't seem to get is that the so called greenhouse gasses also have an emission spectra that tells us that they emit what they absorb at a very slightly lower wavelength due to the energy required to cause a vibration. They don't retain any of that IR.
They emit non-directionaly. That is, about half of what they absorb will be emitted back to the Earth. So, if you add more GHGs to the atmosphere, they will absorb more, and a higher percentage of energy that would normally be lost to space will be retained here on Earth. Another point, as the atmosphere warms from the actions of CO2, it retains more H2O. Which warms it further.
Simple logic, lost on you.