Fun:Dry lightning

Dry lightning, also known as "bolts from the blue" is a weather phenomenon that occurs in regions near thunderstorms where it is not necessarily cloudy. Dry lighting can be deadly.

Dry lightning is a lightning strike from a positively charged thunderstorm anvil to a negatively charged Earth (relative to the anvil), as opposed to normal lightning during thunderstorms that is caused by a potential difference between a negatively charged thunderstorm base and a positively charged Earth (relative to the base).

"Positive charge" and distance leading to greater current claims
The Miami Herald reports that dry lighting packs 10 times the current as normal lightning. The Miami Herald further claims that it has positive charge. However, the Miami Herald is imprecise with its language; Dry lightning is sometimes referred to as positive lightning because the current results from a potential difference between a positively charged thunderstorm anvil and a (relative to the anvil) negatively charged Earth.

Even the NOAA page on dry lightning is imprecise. It states

What makes the strike so dangerous is the fact that the lightning bolt must travel such a long distance from the top of the cloud to the surface. This means that such bolts must carry an extremely large electrical current if they are to complete the circuit between cloud and ground.

However, the NOAA explanation is incomplete, or even suspect pseudoscience. Dry lightning requires a larger potential difference to start the current flow to overcome the greater dielectric (resistance) due to the greater distance, but does not prima facie necessitate a larger current. It is possible that the current is in fact larger, but exactly how the distance causes this is not clear from the NOAA explanation.

Forest fires
Dry lighting is a major cause of forest fires in the United States according to USA Today.

Notable strikes

 * Dry lightning struck 28 miles from a Kansas thunderstorm anvil on May 7, 2004 in Hastings county, Nebraska, according to the NOAA.
 * David Canales was struck dead on June 22, 2007 in Dade County, Florida, with blue skies above, according to the Miami Herald.