The Science of 4th of July Fireworks

StartsWithABang writes: There are few things as closely associated with American independence as our willingness and eagerness to celebrate with fiery explosions. I refer, of course, to the unique spectacle of fireworks, first developed nearly a millennium ago halfway across the world. But these displays don't happen by themselves; there's an intricate art and science required to deliver the shows we all expect. So what's the science behind fireworks? Here's the physics (and a little chemistry) behind their height, size, shape, color and sound, just in time for July 4th!