Research topic: stratosphere

stratosphere , second lowest layer of the earth's atmosphere . The level from which it extends outward varies with latitude; it begins c.5 1/2 mi (9 km) above the poles, c.6 or 7 mi (c.10 or 11 km) in the middle latitudes, and c.10 mi (16 km) at the equator, and extends outward c.20 mi (32 km). It is a zone of dry, thin air, cold and clear, with a horizontal temperature gradient, that, in its lower level, is the reverse of that near the earth's surface. In polar regions the temperature is -40°F to -50°F (-40°C to -46°C), but near the equator it ranges from -80°F to below... Read more