Beth Kohn, age 9, of Montgomery, Alabama, for her question:

What makes heat lightning?

Ordinary lightning comes with a roar of thunder. It is a jagged golden flash from a stormy cloud that is fairly high in the sky, maybe even right overhead. Heat lightning happens lower in the sky. It flashes a great sheet of light through the clouds. We wait to hear the thunder, but it does not come.

Actually, heat lightning is just the same as ordinary lightning. When it happens, it flashes a golden streak and howls a roar of thunder. But the flash is light and the roar is sound    and these are two very different things. Light travels very far and very fast. Sound is a slowpoke that soon grows tired and fades away. Heat lightning comes from a storm that looks low in the sky because it is miles away from us. We see the flashes, lighting up the distant clouds. But the roaring thunder grows weary and fades away before it reaches our ears.