I've never understood the bat signal as it was. A light? To notify someone in a deep underground cave?

You'd think if it were for a bat a special high frequency sound would be good. Could tell people in general that the signal may or may not be running but they cannot hear it.

It would only work if it's cloudy, the light needs something to stop it. If the sky was clear the light would just continue off into space where some aliens would see it and think the people on that planet must be batty.

Happens everytime there is a baseball game. Bunt signal and Steal signal too.