Richard Fry wrote:
. . .

I've discussed the difference between sky and ground wave, and Brown,
Lewis, and Epstein's measurements a number of times on this newsgroup in
response to pretty much the same questions by Richard, so there's no
need to do it again. Anyone interested in my comments can do a search of
my postings which include "ground wave" or "surface wave".

Roy Lewallen, W7EL