How does carbon dioxide methane and water vapour trap heat in the atmosphere?

Answer 1

Actually, all gases do this to some extent. This is sometimes called the greenhouse effect, although the physics driving it work nothing like a greenhouse. Without the atmosphere's greenhouse effect, this would be a cold, dead planet with an average temperature well below zero (F). The Earth gets heat from solar radiation, but like all objects, it will re-emit some of this radiation back into space, losing its potential heating effect (what proportion is lost to re-emission varies from substance to substance). Now, the gases in the atmosphere have this same property, so it absorbs some of the energy Earth emits and does the same thing, sending some of Earth's emitted radiation right back to the Earth, which is then warmed because it gets back some of the energy it emits. But as I wrote, some substances are better at doing this than others, and the problem is that the gases you mention are very good at it. If their concentration in tbe atmosphere increases, then the air as a whole also gets better at it, increasing the greenhouse warming effect.