This article explains how to quickly create cartoon clouds. Ok, let's get to it. Use the Elliptical Marquee tool to make an oval. Fill this with white and give it a bluish gradient overlay. Make sure the top color for the gradient is white and the bottom is a light blue.
Duplicate this circle 4 times and position them randomly around your document. Alter the sizes on each one so they're different. Make sure they all overlap when you position them.
Merge all of the layers together. Duplicate this combined layer. You now have 2 similar layers. Pick the bottom layer and give it a light blue 3px stroke.
Now goto the top layer and apply a gaussian blur on it. Set the blur radius to 4. Double click this layer and apply a Bevel and Emboss. Set depth to 80, size to 5, soften to 16 and the shadow color to a light blue.