James, OK, I forgot about refration, but maybe you are over-compensating. The deviation of light from a celestial body due to refraction of the earth's atmosphere is greater that the deviation due lightning because the lightning take place withoin the atmosphere. If the point that is being viewed ic close to the ground then the factor is 3.56 while if it is on the fringes of space the factor is 3.84. In practice, I beleive that the flash associated with ligthning is somewhere between the two.
Regards Martin ----- Original Message ----- From: "James R. Frysinger" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[email protected]> Cc: "U.S. Metric Association" <[email protected]> Sent: Friday, December 23, 2005 4:50 AM Subject: [USMA:35446] Re: Lightning and thunder > Martin, > > Euclid was pretty good with that geometry stuff but he was weak on refraction. > The rule of thumb I stated takes refraction into account, which is important > to observers near the Earth's surface. Hence the factor of 3.84 rather than > the value of 3.56 that Euclid would have predicted. For radar ranges to the > horizon, add another 2 % to 3 %, especially for the lower frequency radars. >
