Refraction really does happen
 

On both Thursday and Friday evenings I was able to see the setting sun when its calculated geometrical altitude was -0.5°. From my front bedroom window the land slopes to the NW but at a shallow angle (about 0.7°) and there are useful gaps in the trees. The height of this viewpoint only adds 0.1-0.2 degree to the dip of the horizon.
I shall probably be able to do this observation Saturday night, Sunday night and far as I can see, for ever. Soil is now like concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

Refraction really does happen
 

On 23/06/2018 04:47, Tudor Hughes wrote:
On both Thursday and Friday evenings I was able to see the setting sun when its calculated geometrical altitude was -0.5°. From my front bedroom window the land slopes to the NW but at a shallow angle (about 0.7°) and there are useful gaps in the trees. The height of this viewpoint only adds 0.1-0.2 degree to the dip of the horizon.
I shall probably be able to do this observation Saturday night, Sunday night and far as I can see, for ever. Soil is now like concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

If the horizon is really clear and distant watch out for the green flash
as the very last 5% sliver of the sun finally sets a thin line of green
will appear to separate from it. Hot sunny days most likely to have the
right atmospherics to create the right dispersive refraction effects.

Usual warnings apply about staring at the sun through optical aids (DON'T).

Don't look directly at it too soon naked eye though either!

I find watching it intermittently reflected off a window aids timing
when to look directly without being dazzled and stand the best chance of
catching the fleeting green line effect which only lasts 2-10s.

https://en.wikipedia.org/wiki/Green_flash

Setting up a camera to photograph one pretty much ensures that it won't
occur even if conditions seem perfect.

--
Regards,
Martin Brown

Refraction really does happen
 

On Saturday, June 23, 2018 at 9:13:53 AM UTC+1, Martin Brown wrote:
On 23/06/2018 04:47, Tudor Hughes wrote:
On both Thursday and Friday evenings I was able to see the setting sun when its calculated geometrical altitude was -0.5°. From my front bedroom window the land slopes to the NW but at a shallow angle (about 0.7°) and there are useful gaps in the trees. The height of this viewpoint only adds 0.1-0.2 degree to the dip of the horizon.
I shall probably be able to do this observation Saturday night, Sunday night and far as I can see, for ever. Soil is now like concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

If the horizon is really clear and distant watch out for the green flash
as the very last 5% sliver of the sun finally sets a thin line of green
will appear to separate from it. Hot sunny days most likely to have the
right atmospherics to create the right dispersive refraction effects.

Usual warnings apply about staring at the sun through optical aids (DON'T).

Don't look directly at it too soon naked eye though either!

I find watching it intermittently reflected off a window aids timing
when to look directly without being dazzled and stand the best chance of
catching the fleeting green line effect which only lasts 2-10s.

https://en.wikipedia.org/wiki/Green_flash

Setting up a camera to photograph one pretty much ensures that it won't
occur even if conditions seem perfect.

--
Regards,
Martin Brown

I've seen the green flash a couple of times out at Sennen, near Lands End. Mainly because I spend a lot of time staring across the sea to the horizon, and the garden of the Old Success faces the summer sunset.

Being in the far SW the air tends to be cleaner than inland & further east, which helps.

I should think trying to predict it is a virtually a lost cause. You are guaranteed to get a slither of cloud in just the wrong place.

The strangest conditions over the sea are when you are sitting on the beach late evening, and can clearly hear people talking whilst they are sitting in a boat 1 mile offshore. It takes a while for the brain to accept what you're hearing.

Graham
Penzance

Refraction really does happen
 

On 23/06/2018 10:06, Graham Easterling wrote:
On Saturday, June 23, 2018 at 9:13:53 AM UTC+1, Martin Brown wrote:
On 23/06/2018 04:47, Tudor Hughes wrote:
On both Thursday and Friday evenings I was able to see the setting sun when its calculated geometrical altitude was -0.5°. From my front bedroom window the land slopes to the NW but at a shallow angle (about 0.7°) and there are useful gaps in the trees. The height of this viewpoint only adds 0.1-0.2 degree to the dip of the horizon.
I shall probably be able to do this observation Saturday night, Sunday night and far as I can see, for ever. Soil is now like concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

If the horizon is really clear and distant watch out for the green flash
as the very last 5% sliver of the sun finally sets a thin line of green
will appear to separate from it. Hot sunny days most likely to have the
right atmospherics to create the right dispersive refraction effects.

Usual warnings apply about staring at the sun through optical aids (DON'T).

Don't look directly at it too soon naked eye though either!

I find watching it intermittently reflected off a window aids timing
when to look directly without being dazzled and stand the best chance of
catching the fleeting green line effect which only lasts 2-10s.

https://en.wikipedia.org/wiki/Green_flash

Setting up a camera to photograph one pretty much ensures that it won't
occur even if conditions seem perfect.

--
Regards,
Martin Brown

I've seen the green flash a couple of times out at Sennen, near Lands End. Mainly because I spend a lot of time staring across the sea to the horizon, and the garden of the Old Success faces the summer sunset.

Being in the far SW the air tends to be cleaner than inland & further east, which helps.

I should think trying to predict it is a virtually a lost cause. You are guaranteed to get a slither of cloud in just the wrong place.

The strangest conditions over the sea are when you are sitting on the beach late evening, and can clearly hear people talking whilst they are sitting in a boat 1 mile offshore. It takes a while for the brain to accept what you're hearing.

Graham
Penzance


And the inverse.
I was on a boat anchored off the beach in Beer Cove, Dorset.
Just so happened to be at the audio focus of the curve of the cliffs and
a really wird sound effect of the breaking waves, being summed together.

One of the talks , of the series I run, was on atmpspheric refraction
effects, transcript towards the end of this file
http://www.diverse.4mg.com/scicaf2012b.htm

Refraction really does happen
 

Tudor Hughes wrote:

On both Thursday and Friday evenings I was able to see the setting
sun when its calculated geometrical altitude was -0.5°. From my
front bedroom window the land slopes to the NW but at a shallow angle
(about 0.7°) and there are useful gaps in the trees. The height of
this viewpoint only adds 0.1-0.2 degree to the dip of the horizon.
I shall probably be able to do this observation Saturday night,
Sunday night and far as I can see, for ever. Soil is now like
concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

In my years on the Ocean Weather Ships in the 1960s our ship did
occasional tours of duty at Ocean Station 'Alpha' (62°N 33°W) in the
Denmark Strait. I remember at least a couple of occasions when the
Greenland icecap was clearly visible to the NW even though it was more
than 300 miles away. No doubt refraction played a part in that but it
also says a lot for the clarity of the air.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

Refraction really does happen
 

On Saturday, 23 June 2018 11:07:03 UTC+1, Norman Lynagh wrote:
Tudor Hughes wrote:

On both Thursday and Friday evenings I was able to see the setting
sun when its calculated geometrical altitude was -0.5°. From my
front bedroom window the land slopes to the NW but at a shallow angle
(about 0.7°) and there are useful gaps in the trees. The height of
this viewpoint only adds 0.1-0.2 degree to the dip of the horizon.
I shall probably be able to do this observation Saturday night,
Sunday night and far as I can see, for ever. Soil is now like
concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

In my years on the Ocean Weather Ships in the 1960s our ship did
occasional tours of duty at Ocean Station 'Alpha' (62°N 33°W) in the
Denmark Strait. I remember at least a couple of occasions when the
Greenland icecap was clearly visible to the NW even though it was more
than 300 miles away. No doubt refraction played a part in that but it
also says a lot for the clarity of the air.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

Or maybe the earth is flat and very clean.

There is never such clarity here, obviously, but I was surprised how low the apparent horizon was from what is basically a villagey outer suburb. Maybe a short trip to Botley Hill (877 ft) is called for but not tonight with all the thick Cs around.

Tudor Hughes, Warlingham, NE Surrey, 557 ft, 170 m.

Refraction really does happen
 

"Norman Lynagh" wrote in message
...
Tudor Hughes wrote:

On both Thursday and Friday evenings I was able to see the setting
sun when its calculated geometrical altitude was -0.5°. From my
front bedroom window the land slopes to the NW but at a shallow angle
(about 0.7°) and there are useful gaps in the trees. The height of
this viewpoint only adds 0.1-0.2 degree to the dip of the horizon.
I shall probably be able to do this observation Saturday night,
Sunday night and far as I can see, for ever. Soil is now like
concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

In my years on the Ocean Weather Ships in the 1960s our ship did
occasional tours of duty at Ocean Station 'Alpha' (62°N 33°W) in the
Denmark Strait. I remember at least a couple of occasions when the
Greenland icecap was clearly visible to the NW even though it was more
than 300 miles away. No doubt refraction played a part in that but it
also says a lot for the clarity of the air.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

Your note, Norman, reminded me of the occasion when I was on the Weather
Monitor in 1962, I think it was station Juliet, while we were doing the 0600
pilot ascent. I was at the plotting table, and glanced out of the porthole
as the sun rose in my line of sight. I was excited to see my first green
flash, then as the ship rose and fell on the swell, I saw a brilliant blue
flash, then another green one, all in the space of about 10 seconds. I have
seen a couple of lesser examples of the green flash since, but never again
seen the blue one.
I did 2 trips to station Alpha, but never had the experience of a visual
sighting of the Greenland coast. However, we did have radar refraction
during anticyclonic weather, so that the Greenland coast was clearly visible
on the radar display, well beyond the maximum radar range. Then, as the
anticyclone moved eastwards, a couple of days later, after the Greenland
coast had faded, the coast of Iceland appeared. If my memory serves me, the
normal maximum radar range was about 150 km.

--
Bernard Burton

Satellite images and weather data for Wokingham at:
www.woksat.info/wwp.html



---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Refraction really does happen
 

Bernard Burton wrote:

"Norman Lynagh" wrote in message
...
Tudor Hughes wrote:

On both Thursday and Friday evenings I was able to see the setting
sun when its calculated geometrical altitude was -0.50. From my
front bedroom window the land slopes to the NW but at a shallow
angle (about 0.70) and there are useful gaps in the trees. The
height of this viewpoint only adds 0.1-0.2 degree to the dip of
the horizon. I shall probably be able to do this observation
Saturday night, Sunday night and far as I can see, for ever.
Soil is now like concrete (heavy clay over chalk).

Tudor Hughes, Hamsey Green, Warlingham, Surrey, 557 ft, 170 m.

In my years on the Ocean Weather Ships in the 1960s our ship did
occasional tours of duty at Ocean Station 'Alpha' (620N 330W) in the
Denmark Strait. I remember at least a couple of occasions when the
Greenland icecap was clearly visible to the NW even though it was
more than 300 miles away. No doubt refraction played a part in that
but it also says a lot for the clarity of the air.

-- Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

Your note, Norman, reminded me of the occasion when I was on the
Weather Monitor in 1962, I think it was station Juliet, while we were
doing the 0600 pilot ascent. I was at the plotting table, and glanced
out of the porthole as the sun rose in my line of sight. I was
excited to see my first green flash, then as the ship rose and fell
on the swell, I saw a brilliant blue flash, then another green one,
all in the space of about 10 seconds. I have seen a couple of lesser
examples of the green flash since, but never again seen the blue one.
I did 2 trips to station Alpha, but never had the experience of a
visual sighting of the Greenland coast. However, we did have radar
refraction during anticyclonic weather, so that the Greenland coast
was clearly visible on the radar display, well beyond the maximum
radar range. Then, as the anticyclone moved eastwards, a couple of
days later, after the Greenland coast had faded, the coast of Iceland
appeared. If my memory serves me, the normal maximum radar range was
about 150 km.


I'm still waiting to see my first green flash. Not much chance of it in
the Derbyshire hills!

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr