Fortis watch cosmonautis stratoliner ceramic am 4012632 l10 the stratosphere is part of the atmosphere surrounding the earth it is located between 15 and 50 kilometers above sea level in contrast to the surrounding troposphere the temperature increases from 60 degrees to degrees due to the ozone absorbed uv radiation which converts electromagnetic radiation into heat already in the 60s pilots of reconnaissance flights such as the us with the lockheed u 2 needed a reliable technique