Whether the ray originates from a celestial body or from a high-atmosphere event, we're talking about a ray tangent to the Earth's surface at the viewer's horizon. One could argue about small changes those two origins cause in the amount of refraction. It still rounds to a factor of 4.
We could nano-parse the matter, Martin, but I think we have far exceeded the scope of the answer the original question sought. Jim On Monday 26 December 2005 14:24, Martin Vlietstra wrote: > 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. -- James R. Frysinger Lifetime Certified Advanced Metrication Specialist Senior Member, IEEE http://www.cofc.edu/~frysingj [EMAIL PROTECTED] [EMAIL PROTECTED] Office: Physics Lab Manager, Lecturer Dept. of Physics and Astronomy University/College of Charleston 66 George Street Charleston, SC 29424 843.953.7644 (phone) 843.953.4824 (FAX) Home: 10 Captiva Row Charleston, SC 29407 843.225.0805
