Design in Flash

I need 1 Flash banner (ie 300x250) that has a blue background and clouds. The cloud particle system is in a constant state of motion, and it transitions at some point to create a word or an image. This image can be provided in the form of an transparent PNG or gif. Im requiring particle generation code that creates text that is formed from moving clouds (the ones in the sky). Im creating some Flash banners that require an image and text to be written/drawn from clouds using some particle effect. Its like the attached but animated..initially there are just clouds on a blue background they then start a transition and either form text or an image.