.... just got around to looking at the Hurn sunshine figures for June
and setting them against the record as published on the Met Office web
site (starts 1969 for sunshine).

As Philip would say, the usual caveats apply (Kipp & Zonen sensors
[KZS] in use since May 2004, these figures 'rectified' to a pseudo
Campbell-Stokes (CSR) figure using the Kerr/Tabony 'fudge' factors as
published.

The total for June 2010 was 279 hr (KZS), which 'rectifies' to a CSR
figure of 338 hr.

By this measure, June 2010 was the sunniest such-named month in the
1969+ record and the second-sunniest *any* month in that record at
Hurn. The previous sunniest June was in 2006, and this was followed by
the (currently) sunniest *any*-named month of July 2006 (368
hr/CSR-equivalent)

Using the figures published by Ian Currie in his "Dorset Weather
Book", then it's possible that this June just gone is close to or
perhaps exceeds the values for sunshine recorded in 'Bournemouth' in
1925 (site not listed - perhaps King's Park?). This was part of an
extended 'absolutely dry' period (British Rainfall Organisation
definition) across much of England.

Allowing for the caveats, for this area of England anyway, I think we
can say that June 2010 was amongst the 2 or 3 sunniest Junes in over
80 years, and perhaps within the top-5 or so *any*-named sunniest
months in that period.

Martin.

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

The total for June 2010 was 279 hr (KZS), which 'rectifies' to a CSR
figure of 338 hr.

I recorded 316 hours of sunshine for this June with a R&D type sun sensor.

How would that compare with the old CSR?

Thinking about it, the R&D sensor would not record as much sunshine during
days with frequent sunny intervals. But I cannot imagine the CSR would
record sunshine to within 10 - 15 minutes after sunrise and before sunset,
as my R&D does. I did think that over time the two differences cancel each
other out and the values would be pretty similar.

Whatever the outcome, this June was certainly sunny and there were days
where the sun shone through thin, high cloud but there was too diffuse a
shadow for the R&D sensor and it failed to record as much sunshine as there
really was. Maybe a CSR would have registered more sunshine under those
conditions. Are there any studies to determine the differences? If I had a
CSR I would certainly trial them side-by-side.
_____________________
Nick
Otter Valley, Devon
83 m amsl
http://www.ottervalley.co.uk

"Nick Gardner" wrote in message
...
The total for June 2010 was 279 hr (KZS), which 'rectifies' to a
CSR figure of 338 hr.

I recorded 316 hours of sunshine for this June with a R&D type sun
sensor.

How would that compare with the old CSR?

.... can't help there; not sure if a side-by-side study has been
performed - does anyone know?


Thinking about it, the R&D sensor would not record as much sunshine
during days with frequent sunny intervals. But I cannot imagine the
CSR would record sunshine to within 10 - 15 minutes after sunrise
and before sunset, as my R&D does. I did think that over time the
two differences cancel each other out and the values would be pretty
similar.

.... the (long acknowledged) problem with the CSR is that on days of
broken / fitful but strong sunshine, the card 'overburns' and so in
general, CSR values are/were higher than for 'electronic' sensors; I
believe that during the summer months, the difference can be as much
as 15-20%.

Martin.


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

Weymouth had 320.5h in June.
It was the second sunniest June there since 1890.
They still use a C/S recorder - I hope!

Roger