[mez-uh-sfeer, mes-, mee-zuh-, -suh-] 
| 1. | (in the classification of the earth's atmosphere by chemical properties) the region between the ionosphere and the exosphere, extending from about 250–650 mi. (400–1050 km) above the surface of the earth. |
| 2. | (in the classification of the earth's atmosphere by thermal properties) the region between the stratosphere and the thermosphere, extending from about 20–50 mi. (32–80 km) above the surface of the earth. |
| mes·o·sphere (měz'ə-sfîr', měs'-) n. 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. mes'o·spher'ic (-sfîr'ĭk, -sfěr'-) adj. |
| mesosphere (měz'ə-sfîr') Pronunciation Key
The region of the Earth's atmosphere lying above the stratosphere and below the thermosphere, from a height of about 50 km (31 mi) to about 80 km (50 mi) above the Earth's surface. In the mesosphere temperatures decrease with increasing altitude due to the decreasing absorption of ultraviolet radiation from the Sun. At the top of this region temperatures are around -95°C (-135.4°F). Most of the meteors that enter Earth's atmosphere burn up while passing through the mesosphere. See also exosphere, stratosphere, thermosphere, troposphere., See illustration at atmosphere. |
əˌsfɪər