Tropopause
WordNet
noun
(1) The region of discontinuity between the troposphere and the stratosphere
WiktionaryText
Noun
- The zone of transition between the troposphere and the stratosphere (approximately 13 kilometers). The tropopause normally occurs at an altitude of between 25,000 and 45,000 feet in polar and temperate zones. It occurs at 55,000 feet in the tropics.