cold trap

Noun

cold trap (plural cold traps)

1. In vacuum applications, a device that condenses all vapours except the permanent gases into a liquid or solid, typically to prevent contamination of a vacuum pump.
2. An atmospheric layer that is significantly colder than the adjacent layers both deeper and higher. It keeps ascending gases that have high melting points from escaping the atmosphere by freezing them to a solid which then drops back to the planet surface.
   • The impact of a large body in the oceans would inject large quantities of water through the tropopause cold trap into the stratosphere and lower mesosphere.1983, Christopher P. McKay, Gary E. Thomas, “Formation of noctilucent clouds by an extraterrestrial impace”, in Geological Implications of Impacts of Large Asteroids and Comets on the Earth, →ISBN
   • Since the tropopauses of these planets are very cold, there is effectively a cold trap, which in the absence of any other sources should keep the stratospheric water abundance very low, as discussed in Section 4.3.3.2009, Patrick Irwin, Giant Planets of Our Solar System: Atmospheres, Composition, and Structure, →ISBN, page 97