In reply to Frederick Sparber's message of Sun, 17 Dec 2006 04:21:43 -0700: Hi, [snip] >It seems that there is a substantial difference between the Earth's >net negative charge (~ 500,000 C) and it's surface charge (`26,000 C). > >http://www.nofc.forestry.ca/fire/faq_lightning_e.php#one > >"The Earth is electrically charged and acts as a spherical capacitor. The >Earth has a net negative charge of about a million coulombs, while an equal >and positive charge resides in the atmosphere." > >AND amongst others that are close. > >http://www.madsci.org/posts/archives/2000-10/972662284.Es.r.html > >"The solid Earth has a negative charge of about a half million coulombs. The >atmosphere has a roughly equal and opposite charge, so that the Earth as a >whole is roughly neutral. The charge difference produces a "fair weather >electric field" in the lower atmosphere averaging about 6 volts per meter -- >however, this field varies strongly with altitude, and is nearly 100 volts per >meter at ground level. The total voltage difference between the ground charge >and the atmosphere's charge (which exists roughly 30-50 km up) is about >300,000 volts. A simple calculation shows that the total energy stored in the >fair weather electric field is 150 billion joules."
The formula for the capacitance of concentric spheres is: 4*Pi*epsilon_0/((1/Re) + (1/(Re + d))) which works out to 0.095 F when Re is the radius of the Earth, and d = 48 km. Perhaps this is different when the spheres are not concentric thin shells? The charge is of course C*V. Regards, Robin van Spaandonk http://users.bigpond.net.au/rvanspaa/ Competition provides the motivation, Cooperation provides the means.
