The actual atmospheric temperature profile is more complicated, being roughly 290 K at the surface, 200 K at the tropopause (15 km), 270 K at the stratopause (50 km), 200 K at the mesopause (80 km), then increasing again to large values in the thermosphere. (realclimate.org)
The mesopause, at an altitude of about 80 km, separates the mesosphere from this outermost layer of the Earth's atmosphere. (realclimate.org)
The top of the mesosphere, called the mesopause, is the coldest part of Earth's atmosphere, with temperatures averaging about minus 130 degrees F (minus 90 C). (space.com)