Alan White wrote:
What did happen to it?

From Roehampton University website
(http://www.roehampton.ac.uk/weather/...p#frosthollow: )

"1. The Chiltern Hills and North Downs

Since London lies in a basin, valleys tend to run towards the capital -
hence the potential interaction between the frost hollow and the
heat-island. The 'donor' areas for the cold air are the hills around
London - notably the Chiltern Hills to the north-west and the North
Downs to the south. The dip slope of both Chalk outcrops runs towards
London. Dry valleys in Chalk are most appropriate 'reception' areas for
frost hollows. On a calm, clear evening, cold air will run down these
shallow valleys towards the edge of London. The most famous frost hollow
probably is that at Rickmansworth in Hertfordshire, where a dry valley
from the Chiltern Hills meets the larger valley of the river Colne.

Confluences of valleys are effective frost hollows because two streams
of cold air meet and therefore become trapped in that location. This
effect is accentuated at Rickmansworth by a railway embankment across
the end of the dry valley. Air frost has been recorded in every month of
the year here, comparable to the Scottish Highlands. On 29th August 1936
the temperature climbed from 1.1 C at dawn to 29.4 C within 9 hours, the
largest daily range in temperature recorded in Britain.

To the south of London, dry valleys running northwards towards Croydon
have the additional favouring factor of a northward aspect. The
Chipstead valley has similarities to Rickmansworth, even including a
railway embankment which acts as a dam, above which cold air can 'pond-up'."

--
Joe
Wolverhampton

"George Booth" wrote
From 'The English Climate' by H.H. Lamb

'Among the foothills of the Chiltern Hills between Rickmansworth and
Chorleywood, Herts, is a residential district in a little valley 177 feet
above sea level, with the surrounding hills a hundred feet higher. This is
our best studied frost hollow.

This, plus the location given as "Valley Road" have enabled me to make a
better guess of the location.

http://tinyurl.com/5nr7n

(hope that link works!)

However, now that the area is so heavily built up, I would expect that the
frost hollow is very much a thing of the past and there will be much colder
places elsewhere in the local area (eg my original suggstion of Chorleywood
Common)

Jack

On Tue, 1 Feb 2005 07:19:09 -0000, "Jack Harrison"
wrote:

"George Booth" wrote
From 'The English Climate' by H.H. Lamb

'Among the foothills of the Chiltern Hills between Rickmansworth and
Chorleywood, Herts, is a residential district in a little valley 177 feet
above sea level, with the surrounding hills a hundred feet higher. This is
our best studied frost hollow.

This, plus the location given as "Valley Road" have enabled me to make a
better guess of the location.

http://tinyurl.com/5nr7n

(hope that link works!)

However, now that the area is so heavily built up, I would expect that the
frost hollow is very much a thing of the past and there will be much colder
places elsewhere in the local area (eg my original suggstion of Chorleywood
Common)

Yes the link works, Jack - and I'm sure from what the locals have said
that Valley Road is right. My estimate of Hawke's location is about
400 metres East of yours, closer to the junction of Valley Road and
The Drive (National Grid ref: TQ 05370 95300, elevation 177 feet
amsl). Streetmap link for the junction is http://tinyurl.com/5pa49 .
The nearby A404 is about 50 feet up the valley side at its junction
with Valley Road.

The extract from Lamb's book suggests that the blocking railway
embankment (and a road or foot bridge under) is 300 yards to the SSW
of the road junction I mentioned. The route to the railway embankment
would be South along The Drive then SW along Winchfield Way. As to
Hawke's exact location, I'd guess he was on Valley Road, about 100
yards West of the road junction I mentioned.

Can any "locals" or National Weather Historians confirm that Jack
and I have it right and hopefully be even more exact?

--
Dave

Yes the link works, Jack - and I'm sure from what the locals have said
that Valley Road is right. My estimate of Hawke's location is about
400 metres East of yours, closer to the junction of Valley Road and
The Drive (National Grid ref: TQ 05370 95300, elevation 177 feet
amsl). Streetmap link for the junction is http://tinyurl.com/5pa49 .
The nearby A404 is about 50 feet up the valley side at its junction
with Valley Road.

The extract from Lamb's book suggests that the blocking railway
embankment (and a road or foot bridge under) is 300 yards to the SSW
of the road junction I mentioned. The route to the railway embankment
would be South along The Drive then SW along Winchfield Way. As to
Hawke's exact location, I'd guess he was on Valley Road, about 100
yards West of the road junction I mentioned.

Can any "locals" or National Weather Historians confirm that Jack
and I have it right and hopefully be even more exact?

--
Dave
I can't confirm that to be the exact location but the drop from the A404 to
that point is very steep.

Alan

In article ,
Alan White writes:
On Mon, 31 Jan 2005 20:12:54 +0000, John Hall
wrote:

Yes, I recall reading somewhere (Manley?) that the construction of the
railway embankment completed the hollow.

I first came across it in 'Climate and the British Scene', Manley, but
it never seems to be mentioned these days.


The record there seems to have been maintained by EL Hawke. When he
moved on (or possibly died), it may have lapsed. Or of course the site
may have changed in some way, such that conditions are now less extreme.
--
John Hall
"Honest criticism is hard to take,
particularly from a relative, a friend,
an acquaintance, or a stranger." Franklin P Jones

If I might be permitted to disobey the injunction in another thread not to add
to this one - I'll be brief :-) - a large scale map of the frost hollow will
appear in a two-part article (examining whether the frost hollow has weakened)
written for Weather by Jim Galvin. It will appear this spring. Dave and Jack
have the location right - immediately north of the railway embankment.

Julian Mayes
Molesey
Surrey.

On Mon, 31 Jan 2005 18:19:54 +0000, Alan White
wrote:

What did happen to it?

So the answer would appear to be 'nothing, it's still there'.

Thanks to all for their answers.

--
Alan White
Twenty-eight miles NW of Glasgow, overlooking Loch Goil and Loch Long in Argyll, Scotland.
Web cam, http://www.ufcnet.net/~alanlesley1/kabcam.htm
Web site, http://www.alan.lesley.ukgateway.net