From Jetstream Online School For Weather produced by the National Weather Service,
A Positive lightning strike can produce as much as 300,000 amperes and ONE BILLION VOLTS! In fact positive lightning has been recorded as striking as far as up to 10 mile away from the parent Thunderstorm, this is known as a bolt from the blue.
READ MORE ON LIGHTNING
http://www.srh.noaa.gov/srh/jetstream/lightning/lightning_intro.htm
http://www.nssl.noaa.gov/primer/lightning/ltg_faq.shtml
http://newweb.wrh.noaa.gov/hnx/LightningMyths-1.pdf
http://library.thinkquest.org/03oct/00758/en/disaster/lightning.html
http://www.ucar.edu/communications/infopack/lightning/faq.html
http://www.srh.weather.gov/srh/jetstream/lightning/lightning_faq.htm
http://www.lightningmaster.com/FAQ.htm
http://www.ourbetternature.org/lightning2.htm
http://www.harkphoto.com/light.html