This tutorial will show you how to use 3D transforms in CSS to create sprite-based realistic 3D clouds. More information on 3D transforms can be found here.
The example can be customized using different types of textures and adjusting them on four levels. Using these you can obtain normal white 3D clouds, dark gray storm clouds and dark lighting storm ones.
Normal clouds preview
Storm clouds preview
Lighting Storm clouds preview
A fully functional demo of the CSS3 3D clouds can he found here.
You can view the 3D clouds tutorial here.