On Sat, 21 May 2005 21:47:12 +0100, Joe Hunt wrote:

Surely when talking of relatively short distances, the effects of
the Earth's curvature are minimal ?

I think you underestimate how curved the surface really is. Humber
bridge the support towers are 36mm further apart at the top than the
bottom. They are only 155m + a bit high but the best part of mile
apart.

http://www.humberbridge.co.uk/interest.htm
http://www.humberbridge.co.uk/techspec.htm

With a cloud top at 20,000' the horizon is 190 miles away, not a short
distance...

--
Cheers
Dave. pam is missing e-mail