Stormy Volumetric Sky HDRI

A stormy sky HDRI made entirely with Blender Cycles volumetrics. The technique took some time to develop, especially due to the obscenely long iteration time that comes with rendering 360 degree panoramas of pure volumetrics with light bounces and several layers of noise. But the result is beautiful and clean, and the technique is flexible and can be applied to many different kinds of skies. When I revisit this, I intend to experiment with integrating simulated smoke physics along with the noise-generated clouds.

Preview pics were also rendered with Blender Cycles, but I've also used this sky in a few Unity projects with great results, even when using the HDRI as the only scene light source.