Ranging in size from one half inch to many meters in diameter, ball lightning can occur in a variety of different colors, the most common being red, orange, and yellow. It's luminous enough to be seen clearly in daylight; rarely is it dazzling. Most instances of ball lightning last only ten seconds or less; instances of more than a minute are rare. Often the object is accompanied by a hissing sound and distinct odor resembling ozone, burning sulfur, or nitric oxide. In most cases, the object will be seen to move about and then vanish, decaying either explosively or silently. "After the ball has decayed, it is sometimes reported that a mist or residue remains," Martin Uman explains. "Occasionally a ball lightning has been observed to break up into two or more smaller balls."1