thermosphere

[ thur-muh-sfeer ]

noun

1. the region of the upper atmosphere in which temperature increases continuously with altitude, encompassing essentially all of the atmosphere above the mesosphere.

thermosphere

/ ˈθɜːməˌsfɪə /

noun

1. an atmospheric layer lying between the mesosphere and the exosphere, reaching an altitude of about 400 kilometres where the temperature is over 1000°C

thermosphere

/ thûr′mə-sfîr′ /

1. The region of the Earth's upper atmosphere lying above the mesosphere and extending from a height of approximately 80 km (50 mi) to between 550 and 700 km (341 and 434 mi) above the Earth's surface. In the thermosphere temperatures increase steadily with altitude, reaching as high as 1,727°C (3,140°F) at the highest elevations. Chemical reactions occur much faster here than on the surface of the Earth.
2. See also exosphereSee illustration at atmosphere

Word History and Origins

Origin of thermosphere¹

First recorded in 1950–55; thermo- + sphere

Example Sentences

They were piercing the thermosphere where the outside temperature gradient would zoom upward toward the 2,000 degree mark.

From Project Gutenberg