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Franklin chimes
grounded
To lightning rod
ringer
Benjamin Franklin
• Ben Franklin proposed Sentry Box experiment in 1750
• D’Alibard demonstrated Sentry Box by ‘drawing fire from clouds’ in 1752 (Franklin became famous as a result)
• At about the same time (1752) Lemmonier discovered Fair Weather Electricity
• Linss 1788: Fundamental Problem of Atmospheric Electricity: Why is there a continuous current from the air to the ground?
• (note: ions not discovered until Elster&Greitel 1899)
• Victor Hess discovered Cosmic Rays in 1911
Electric Field
ConductivityJ = σE is constant in altitude
Global Electric Circuit
First proposed by C.T. R Wilson
Two payloads see same field even though separated by over 1000 km ! So, conclusion is that this variation is planetary-scale sized.
Next time:
http://www.youtube.com/watch?v=9v-4IiqPhnU
Lightning Safety:http://www.srh.noaa.gov/jetstream/lightning/lightning_faq.htm