Main Entry: tro·po·sphere

Pronunciation: \ˈtrō-pə-ˌsfir, ˈträ-\

Function: noun

Etymology: International Scientific Vocabulary

Date: 1909

: the lowest densest part of the earth's atmosphere in which most weather changes occur and temperature generally decreases rapidly with altitude and which extends from the earth's surface to the bottom of the stratosphere

— tro·po·spher·ic \ˌtrō-pə-ˈsfir-ik, ˌträ-, -ˈsfer-\ adjective