Yongwen Zhang

The tropics breathe with an annual rhythm: air temperature rises and falls, and within this breath lie two main pulses. The first pulse peaks in February and weakens in August; the second is shifted by half a year. These two pulses are not just background noise for the famous El Niño; they are its conductors.

In the vast concert hall of the atmosphere, ozone plays a part that changes from tier to tier. Near the surface, its notes sound alarming, for there it is a pollutant that irritates lungs and leaves. At 25 kilometers up, the same gas becomes a protective shield that absorbs harsh ultraviolet radiation.

The Tibetan Plateau is a giant sponge that soaks up rain and snow, then releases water to Asia's rivers. Since 2000, the sponge has been getting wetter. Scientists decided to check: does this moisture make the sponge stronger, or does it soften it? They used a measure of disorder — entropy.