the atmospheric zone or shell located above the stratopause at an altitude of c. 55 to 80 km (c. 34 to 50 miles) and characterized by a decrease in temperature with increasing altitude
Origin:
meso- + sphere
See mesosphere in American Heritage Dictionary 4
noun
The portion of the atmosphere from about 30 to 80 kilometers (20 to 50 miles) above the earth's surface, characterized by temperatures that decrease from 10°C to -90°C (50°F to -130°F) with increasing altitude.