The second major layer of Earth's atmosphere, just above the → troposphere and below the → mesosphere, extending from about 20 km to 90 km above the Earth. It is characterized by little vertical increase in temperature.
From Fr. stratosphère, literally "sphere of layers," coined by Fr. meteorologist Léon-Philippe Teisserenc de Bort (1855-1913) from L. stratus "a spreading out" (from p.p. stem of sternere "to spread out") + -sphère (→ sphere), as in atmosphère.