– By Jane Liu, Lingyun Meng, David W. Tarasick, William J. Randel, Andrea K. Steiner, Hallgeir Wilhelmsen, Lei Wang, Leopold Haimberger, and Wayne K. Hocking –
The tropopause is a transition between the troposphere and the stratosphere above it. Air temperature decreases with altitude from the surface to the tropopause because the surface is a heat source, while above the tropopause, air temperature increases with altitude because the ozone layer in the middle stratosphere is a second heat source. In other words, the tropopause is an altitude where temperature typically reaches a minimum. In some special cases, temperature decreases with altitude again above the tropopause, and then increases with altitude, forming a second tropopause. Rarely, a third tropopause can be formed. Here we only consider the first tropopause.