To sign cloud, take your two open 'C' hands, facing each other, and twisting them away from each other, as if to trace the shape of a cloud. Twist your hands while moving them along. Imagine your fingers are caressing the edges of the cloud. I find this a cool, ethereal sign.
Cloud is an ideal sign to teach during outdoor activities or on a long road trip.
The cloud sign is great to teach your baby because you can use it with lots of picture books as well as when you are playing outside.