Sentence:  The impact of a large body in the oceans would inject large quantities of water through the tropopause <WSD>cold trap</WSD> into the stratosphere and lower mesosphere. 
Meaning of the word marked with <WSD> tags:  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.