Photorealistic cloud image with javascript and three-dimensional CSS transforms

This picture, if at first glance, looks like a photograph of a real cloud in real skies:



However, on the CSS3D Clouds website, the volumetric cloud rotates in response to mouse movements, and can be re-generated (otherwise) at any time. Indeed, in fact, it is the result of applying JavaScript and three-dimensional CSS transformations to several copies of the same cloud image: from them, like voxels, a larger cloud is formed.