Wokingham 6 July 2005
2215z NLC observed between gaps in lower cloud, Az 320-340 deg, El 5 deg.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.btinternet.com/~wokingham.weather/wwp.html

"Bernard Burton" wrote in message
...
Wokingham 6 July 2005
2215z NLC observed between gaps in lower cloud, Az 320-340 deg, El 5 deg.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.btinternet.com/~wokingham.weather/wwp.html


Bernard

Surprised by the clear sky I looked north from J4 on the M3 (Farnborough) at
22.55 GMT last night and saw some white clouds which contrasted clearly with
the black ones still visible. I did not know whether the white clouds were
simply high cirrus still illuminated by the sun (the northern sky was not
completely dark of course) or whether they were indeed of the noctilucent
type. How would I tell the difference?

Regards, Roger

Roger,
To be illuminated by the sun at that time and in that location, they would
have to be at noctilucent cloud height, ca 80km, as any tropspheric clouds
would be in the earth's shadow, and appear black, or nearly so, even cirrus
cloud.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.btinternet.com/~wokingham.weather/wwp.html
"Roger Smith" wrote in message
...

"Bernard Burton" wrote in message
...
Wokingham 6 July 2005
2215z NLC observed between gaps in lower cloud, Az 320-340 deg, El 5
deg.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.btinternet.com/~wokingham.weather/wwp.html


Bernard

Surprised by the clear sky I looked north from J4 on the M3 (Farnborough)
at
22.55 GMT last night and saw some white clouds which contrasted clearly
with
the black ones still visible. I did not know whether the white clouds
were
simply high cirrus still illuminated by the sun (the northern sky was not
completely dark of course) or whether they were indeed of the noctilucent
type. How would I tell the difference?

Regards, Roger

"Bernard Burton" wrote in message
...
Roger,
To be illuminated by the sun at that time and in that location, they would
have to be at noctilucent cloud height, ca 80km, as any tropspheric clouds
would be in the earth's shadow, and appear black, or nearly so, even
cirrus
cloud.

--
Bernard Burton
Wokingham, Berkshire, UK.


Thanks Bernard. I did not have time to do my sums. Because of the clear
sky and the recent reports I was indeed glancing up for sight of noctilucent
clouds when I joined the motorway, but when I saw the illuminated streaks
low down in the north I felt unable to judge whether they were what I was
looking for.

Regards, Roger