If you've ever heard or used the expression "out of the blue", you know that it means something abrupt, sudden, and completely unexpected. It's certainly one way to describe the lightning bolt that struck self-employed landscaper David Canales dead, underneath a clear blue sky completely devoid of clouds.

Scared? You probably should be. Experts say that Canales, 41, was killed by a phenomenon called dry lightning - the name because of its tendency to strike in perfectly-good weather - or weather about to turn nasty. For Canales, it was the latter, as meteorological reports show a storm brewing at the time he was hit, but nowhere near the area the landscaper was in.

It's also to note that this incident happened in Florida - the state that's been given the dubious honor of the country's lightning capital. To better understand how a dry lightning bolt differs from its regular, in-storm cousin, here's a short comparison:

• Wet lightning comes from the base of the thunderstorm, while dry lightning can come from a thunderstorm that's still several miles away from the impact area.
• Wet lightning has a positive charge. Dry lightning, on the other hand, has a negative charge that carries a current ten times stronger than wet lightning - not to mention hotter and lasts longer.
• Dry lightning reaches farther than wet lightning - travelling horizontally before arcing downward.