I went up Bushbury Hill (613ft) yesterday, and noticed the air is quite
dirty. I could just about see the outline of the Wrekin 20 miles away.
Blue sky above at the zenith, dirty grey at the horizon.

It had methinks, at the distance of 20 miles what's difference between
the true and astronomical horizon?



--
Joe Egginton
Wolverhampton
175m asl

I went up Cairnsmore of Carsphairn (2650 ft) yesterday and there was a
rather nice temperature inverstion with other hill tops standing out above
the mist. An absolutely fabulous day in the hills by the way with wall to
wall blue skies above (and cloud below). Ben Lomond visible to the north and
the Lake District hills to the south.

Photo: http://members.multimania.co.uk/scot...edP1030737.jpg

Paul






"Joe Egginton" wrote in message
...
I went up Bushbury Hill (613ft) yesterday, and noticed the air is quite
dirty. I could just about see the outline of the Wrekin 20 miles away.
Blue sky above at the zenith, dirty grey at the horizon.

It had methinks, at the distance of 20 miles what's difference between the
true and astronomical horizon?



--
Joe Egginton
Wolverhampton
175m asl

I went up Cairnsmore of Carsphairn (2650 ft) yesterday and
there was a rather nice temperature inverstion with other hill
tops standing out above the mist. An absolutely fabulous day in
the hills by the way with wall to wall blue skies above (and
cloud below). Ben Lomond visible to the north and the Lake
District hills to the south. Photo:
http://members.multimania.co.uk/scot...edP1030737.jpg

I took a glider up to a little under 3000 feet yesterday
afternoon, and observed the same blue skies above a layer of
mist with the hilltops protruding. The air was absolutely still,
with just a couple of knots of light breeze at ground level. No
photos, I'm sorry, because I didn't take a camera with me. Our
tug pilot, who is a commercial pilot by profession, had flown to
Stornoway and back in the morning and said there had been a
magnificent view over the inversion. However I saw no evidence
of dirty air.

Anne

Joe Egginton wrote:

I went up Bushbury Hill (613ft) yesterday, and noticed the air is quite
dirty. I could just about see the outline of the Wrekin 20 miles away.
Blue sky above at the zenith, dirty grey at the horizon.

It had methinks, at the distance of 20 miles what's difference between the
true and astronomical horizon?


On Sunday I drove over the Cat & Fiddle road to Macclesfield. The summit (515m)
was just at the top of the haze. There was clear deep blue sky above but
everywhere below was filled with grey/brown crud.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.

On Oct 12, 8:59*am, "Anne Burgess"
wrote:
I went up Cairnsmore of Carsphairn (2650 ft) yesterday and
there was a rather nice temperature inverstion with other hill
tops standing out above the mist. An absolutely fabulous day in
the hills by the way with wall to wall blue skies above (and
cloud below). Ben Lomond visible to the north and the Lake
District hills to the south. Photo:
http://members.multimania.co.uk/scot...edP1030737.jpg

I took a glider up to a little under 3000 feet yesterday
afternoon, and observed the same blue skies above a layer of
mist with the hilltops protruding. The air was absolutely still,
with just a couple of knots of light breeze at ground level. No
photos, I'm sorry, because I didn't take a camera with me. Our
tug pilot, who is a commercial pilot by profession, had flown to
Stornoway and back in the morning and said there had been a
magnificent view over the inversion. However I saw no evidence
of dirty air.

Anne

Air in the boundary layer looks decidedly polluted here on the south
coast this morning.

A grey/brown colour appearing surprisingly deeper over the sea.
Camborne ascent shows a strong inversion to 882 mb, about 1200 m.

http://weather.uwyo.edu/cgi-bin/soun...200&STNM=03808

Who is to blame? Our continental neighbours?

Len Wood
Wembury, SW Devon

On Tue, 12 Oct 2010 07:31:01 -0000, Paul C wrote:

Photo: http://members.multimania.co.uk/scot...edP1030737.jpg

members.multimania.co.uk - Host not found. B-(

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.

Dave Liquorice wrote:

On Tue, 12 Oct 2010 07:31:01 -0000, Paul C wrote:

Photo: http://members.multimania.co.uk/scot...edP1030737.jpg

members.multimania.co.uk - Host not found. B-(

No problems here viewing the photo using both Firefox 3 and Internet
Explorer 8.
--
MCC

"Joe Egginton" wrote in message
...
I It had methinks, at the distance of 20 miles what's difference between
the true and astronomical horizon?



--
Joe Egginton
Wolverhampton
175m asl

Joe, not sure what your question is in this context, but a rough-and-ready
figure I use is that at 1000 feet altitude the horizon is 40 miles away. It
is essentially a square root relationship, so that to see a point on the
surface 20 miles away you need to be 250 feet up.

Roger

Photo:
http://members.multimania.co.uk/scot...edP1030737.jpg

members.multimania.co.uk - Host not found. B-(

No problems here. Opened immediately, and well worth the effort
of the click to do so.

Anne

On 12 Oct, 10:46, "Roger Smith" wrote:
"Joe Egginton" wrote in message

...I It had methinks, at the distance of 20 miles what's difference between
the true and astronomical horizon?

--
Joe Egginton
Wolverhampton
175m asl

Joe, not sure what your question is in this context, but a rough-and-ready
figure I use is that at 1000 feet altitude the horizon is 40 miles away. *It
is essentially a square root relationship, so that to see a point on the
surface 20 miles away you need to be 250 feet up.

In a navigator's table the reductions allow for sighting to be reduced
from ship's bridges. I think the horizon observed at sea level is 3
miles. At least, IIRC, that is the computed limb observation time.