In message , Paul Hyett
writes
On Tue, 17 Jun 2008 at 01:32:31, Graham Easterling
wrote in uk.sci.weather :

Excellent visibility dowm in SW Cornwall - Lundy easily visible from
the back of St Ives (around 100km?)

.

I tried plugging some numbers into this :

http://www.ringbell.co.uk/info/hdist.htm

... and you'd need to 800m up for the horizon to be at 100km - and I
know there's no land that high around St Ives.

Wouldn't it depend also on the height of land at the distant point?

I was on a ferry returning to the Isle of Man from England last
Thursday, 12th, in a very clear northerly air flow. The high ground of
the Isle of Man - say above about 1,000 feet - was clearly visible and
my handheld Garmin indicated it to be still some 58 miles (about 90km)
away.

--


Jim