From Wikipedia, the free encyclopedia
In astronomy, a cold trap is a close to the surface layer of the atmosphere that is substantially colder than both the deeper and higher layers. It is called a trap because it keeps ascending gases with high melting points in by freezing them to a solid which then drops back to the planet surface. The most important gas to be kept in that way, on the Earth, is water vapor, which without the presence of a cold trap in the atmosphere (which for the earth resides at about 20 kilometers height) would gradually escape or dissociate into space, making life impossible.
