The Cloudharp Project literally creates music from the clouds.

The Cloud Harp is a meteo-electronic installation that converts real-time, thanks to an infra-red laser beam and a telescope sharing the same optics, the height, density and structure of clouds into sounds and musical sequences. The melodies and sounds are determined by factors such as cloud height, density, structure, luminosity, and meteorological conditions. Each cloudscape produces a particular kind of sequence.

No idea what the actual music sounds like, but the concept is pretty ethereal.