Storm surges have the potential to be dangerous because they involve a great upwelling of a stretch of ocean - intense low pressure at the heart of a storm literally tugs the sea surface above its normal level to create a massive bulge.
In this, the stream of video and audio data is recorded as a series of minuscule spots on the disc's surface that have been gently fried by a laser beam and turned from their normal crystalline condition to an amorphous state that has different reflective properties.