The atmospheric layer between the troposphere and the mesosphere.
Upper atmosphere, from about 7 miles/11 km. up.
That part of the atmosphere 10–40 km/6–25 mi from the Earth's surface, where the temperature slowly rises from a low of -55şC/-67şF to around 0şC/32şF. The air is rarefied and at around 25 km/15 mi much ozone is concentrated.