Anyone know of a discussion - ideally available online - of the
preferred criteria for locating an observing site? (To be clear,
recommendations for the site itself, ie the physical geography, not
for instrument positioning).

There's some obvious things like preferring at least a semi-rural and
not a built-up location, ensuring a suitable distance from trees and
other obstacles. But what I have in mind more is whether there's any
official preference say for a hill-top location where there's
obviously going to be better wind exposure, but which may not be very
representative of the surrounding area. Maybe hilltops should be
avoided? Is it best to avoid locations near to rivers, reservoirs etc,
again as being potentially unrepresentative of the area as a whole?
And so on.

I suspect that many official sites were set up years ago in particular
locations chosen for some rather arbitrary reason such as availability
or convenience. But if you were to have at least some choice for
locating a new site then are there any guidelines for deciding between
possible sites?

John Dann
www.weatherstations.co.uk

"John Dann" wrote :

Anyone know of a discussion - ideally available online - of the
preferred criteria for locating an observing site? (To be clear,
recommendations for the site itself, ie the physical geography, not
for instrument positioning).

snip

John, allow me to quote from the /Observer's Handbook/:
quote
Selection of site
To ensure that the observations are representative of the place
and sufficient comparable with those made at other stations to
permit their use in national or regional studies, the following
basic requirements are laid down for synoptic and climatological
stations.
(A) Outdoor instruments should be installed on a level piece
of ground, approximately 10m by 7m, covered with short grass
and surrounded by open fencing or palings to exluded
unauthorized persons ......
(B) There should be no steeply sloping ground in the vicinity
and the site should not be in a hollow. If these conditions are
not complied with, the readings of temperature and amount of
precipitation may show peculiarities of entirely local significance.
(C) The site should be well away from trees, buildings, walls
or other obstructions. The distance of any such obstacle (including
fencing) from the rain-gauge should not be less than twice the
height of the object from the rim of the gauge, and preferably
four times the height.
(D) The sunshine recorder, rain-gauge and anemometer must
be on sites with exposures to satisfy their requirements and they
need not be on the same site as the other instruments.
(E) As noted [elsewhere] the enclosure may not be the best
place from which to estimate the wind speed and direction;
another observation point, more exposed to the wind, may be
desirable.
(F) Very open sites which are satisfactory for most instruments
are unsuitable for rain-gauges. For such sites the rainfall catch
is reduced in other than light winds and some degree of
shelter is needed [refers to section on turf walls]
(G) If the instrument enclosure does not command a
sufficiently extensive view over the surrounding country,
alternative viewpoints should be selected for observations of
visibility.

The position used for observing cloud and visibility should be
as open as possible and command the widest possible view
of the sky and surrounding country.

In selecting a site the future should be considered as well
as the present. A good site may become a bad one because
of the growth of trees or the erection of buildings on
adjacent plots. Where the station is owned by an urban
authority it should preferably be sited on a scheduled open
space, and the layout of the remainder of the open space
should be such that the exposure will remain unimpaired
for many years.
end quote

These rules were written over half a century ago and
reflect (e.g. the open fencing) a rather different social
environment to today. But they give a good idea of what
was considered important.

Philip

Many thanks Philip - that's very helpful.

I've been trying for some time to get hold of a copy of the Observer's
Handbook but it still appears to be out of print whenever I look -
unless I'm looking in the wrong place! I presume that no-one has any
news of a reprint possibly or any sort of online availability?

(I did see something the other day about a new print-to-order service
that may become available in certain bookshops IIRC for individual
copies of an otherwise out-of-print title - at a price of course but
provided it was not too extortionate then it might be an attractive
option.Too much to hope I guess that the Handbook might become one of
the titles on offer.)

JGD

"John Dann" wrote in message
...
Many thanks Philip - that's very helpful.

I've been trying for some time to get hold of a copy of the
Observer's
Handbook but it still appears to be out of print whenever I look -
unless I'm looking in the wrong place! I presume that no-one has any
news of a reprint possibly or any sort of online availability?

.... Amazon have a few: not sure if it will ever be reprinted; most of
the Met Office stuff is now done online.

Martin.

--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023

John Dann wrote:

Many thanks Philip - that's very helpful.

I've been trying for some time to get hold of a copy of the Observer's
Handbook but it still appears to be out of print whenever I look -
unless I'm looking in the wrong place! I presume that no-one has any
news of a reprint possibly or any sort of online availability?

(I did see something the other day about a new print-to-order service
that may become available in certain bookshops IIRC for individual
copies of an otherwise out-of-print title - at a price of course but
provided it was not too extortionate then it might be an attractive
option.Too much to hope I guess that the Handbook might become one of
the titles on offer.)

JGD


John,

There are several second-hand copies currently available through

http://www.bookfinder.com/

Norman
--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

Thanks for the pointers everyone. I managed to get a copy from Biblio
for £3.99 (plus the same again for 2nd class post). The copy I
received was a hardback in non-mint but generally good condition. It
seems to have belonged to Cornwall County Library, but was last taken
out in 1980 and is marked 'withdrawn' so has probably found its way
legitimately on to the used market. It's a 3rd edition dated 1969 - I
guess I could have asked here what was the latest available edition
but presumably 1969 is not too out-of-date for most of the issues that
it covers.

JGD

On 29 Aug, 17:33, John Dann wrote:
Thanks for the pointers everyone. I managed to get a copy from Biblio
for £3.99 (plus the same again for 2nd class post). The copy I
received was a hardback in non-mint but generally good condition. It
seems to have belonged to Cornwall County Library, but was last taken
out in 1980 and is marked 'withdrawn' so has probably found its way
legitimately on to the used market. It's a 3rd edition dated 1969 - I
guess I could have asked here what was the latest available edition
but presumably 1969 is not too out-of-date for most of the issues that
it covers.

JGD

The latest (and presumably now last) edition is dated 1982, but you're
right - descriptions on sites etc haven't changed all that much from
the 1969 version (I have both).

As I recall, one of the main improvements was in the updating of the
cloud pictures, some of which were distinctly long in the tooth in the
1969 edition, and if I remember rightly the original printing plates
had been lost anyway when the HMSO press was relocated out of the
Bracknell building, so new photographs were included, including a
number of mine as it happens.

--
Stephen Burt
Stratfield Mortimer, Berkshire

On Fri, 29 Aug 2008 at 18:33:05, John Dann wrote in
uk.sci.weather :

Thanks for the pointers everyone. I managed to get a copy from Biblio
for £3.99 (plus the same again for 2nd class post). The copy I
received was a hardback in non-mint but generally good condition. It
seems to have belonged to Cornwall County Library, but was last taken
out in 1980 and is marked 'withdrawn' so has probably found its way
legitimately on to the used market. It's a 3rd edition dated 1969 - I
guess I could have asked here what was the latest available edition
but presumably 1969 is not too out-of-date for most of the issues that
it covers.

You should worry - my edition is dated 1926!
--
Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me)