the zone of minimum temperature between the mesosphere and the thermosphere
mesopause in American English
(ˈmɛsəˌpɔz; ˈmɛzəˌpɔz)
noun
an atmospheric transition zone or shell located between the mesosphere and the thermosphere at an altitude of c. 80 to 85 km (c. 50 to 53 miles) in which temperatures begin to rise with increasing altitude