I think another reason people disappear is ball lightening. They're basically just vaporized in a ball of white fire. Ball lightning could be as small as just a few inches across and contain millions of volts of electricity, and could most probably float around and even go right through certain objects without losing hardly any charge. It could float near you, and then get attracted to you and "stick" to you... as soon as contact is made.. poof... the person is just a ball of white smoke drifting up and the ball lightening continues on its way.