Electric Skies - Thunderstorms and Lightning

EW: The details of charge separation leading to lightning generation are still poorly understood, particularly in comparison with conventional batteries and motor-generators that routinely produce electricity. The inhospitable environment of the thunderstorm has greatly slowed progress toward this solution. We do know that mixed phase conditions, in which water substance in all three of its phases (vapor, liquid, and solid) is an essential aspect of vigorous charge separation. Millimeter- to centimeter- sized graupel particles grow by accreting supercooled droplets which subsequently freeze on the graupel surface to add to its mass. The graupel particles develop appreciable fall speeds relative to the surrounding air and collide with ice crystals and smaller graupel particles. It is widely believed that microphysical differences in these colliding particles lead to selective transfer of negative charge to the larger particles and positive charge transfer to the smaller particles. The subsequent differential motions under gravity result in the large scale vertical dipole of a thundercloud with positive charge uppermost and negative charge in the lower portion of the mixed phase zone.

FS: How many people each year are struck by lightening?

EW: As I recall, approximately 300 people per year are struck by lightning, or about one person per day worldwide. Recent surveys indicate a considerable underreporting of such strikes. A surprisingly large number of people live to tell about a lightning strike to their person. Several medical doctors specialize in lightning injury.

For more information:

See 'Storm Chasers: Fury in the Skies' TV documentary
http://www.firstscience.com/home/firstscience.tv/stormchasers-fury-in-the-skies_8.html

See 'Storm Chasers: Fury in the Plains' TV documentary
http://www.firstscience.com/home/firstscience.tv/storm-chasers-fury-on-the-plains_9.html

See 'Oaklahoma Fury' TV documentary
http://www.firstscience.com/home/firstscience.tv/oklahoma-fury_12.html

See 'When Nature Strikes Back: Chasing Killer Storms' TV documentary
http://www.firstscience.com/home/firstscience.tv/when-nature-strikes-back-chasing-killer-storms_16.html