Early this morning (0450) the humidity recorded by my AWS was 3%, the DP
-29.6.

I suppose everyone's figures were similar? So what caused this surely
exceptionally low figure? Simply the Spanish or Saharan plume?

Hugh

--

Hugh Newbury

www.evershot-weather.org

On 24/07/2014 17:01, Hugh Newbury wrote:
Early this morning (0450) the humidity recorded by my AWS was 3%, the DP
-29.6.

I suppose everyone's figures were similar? So what caused this surely
exceptionally low figure? Simply the Spanish or Saharan plume?

Sounds more like a glitch to me, or was it sustained over a significant
period of time?



--

Paul Hyett, Cheltenham

On Thu, 24 Jul 2014 17:01:11 +0100, Hugh Newbury
wrote:

Early this morning (0450) the humidity recorded by my AWS was 3%, the DP
-29.6.

I suppose everyone's figures were similar? So what caused this surely
exceptionally low figure? Simply the Spanish or Saharan plume?

I think your instrument recording DP failed, or it transmitted/you
recieved an incorrect value. At 04:50 BST here, air temp was 18.0 deg
C, dew point +14.2 deg C, humidity 78%.

This afternooon I did record my lowest humidity of the year so far,
when the air temp. was 29.6 deg C, dewpoint 11.2 deg C, relative
humidity 32%.

--
Dave
Fareham (W)

On 24/07/14 17:15, Vidcapper wrote:
On 24/07/2014 17:01, Hugh Newbury wrote:
Early this morning (0450) the humidity recorded by my AWS was 3%, the DP
-29.6.

I suppose everyone's figures were similar? So what caused this surely
exceptionally low figure? Simply the Spanish or Saharan plume?

Sounds more like a glitch to me, or was it sustained over a significant
period of time?

About 15 minutes. But I expect you're right: a glitch.

Hugh

On Thursday, 24 July 2014 17:20:15 UTC+1, Dave Ludlow wrote:
On Thu, 24 Jul 2014 17:01:11 +0100, Hugh Newbury
wrote:

Early this morning (0450) the humidity recorded by my AWS was 3%, the DP
-29.6.

I think your instrument recording DP failed, or it transmitted/you
received an incorrect value. At 04:50 BST here, air temp was 18.0 deg
C, dew point +14.2 deg C, humidity 78%.

This afternoon I did record my lowest humidity of the year so far,
when the air temp. was 29.6 deg C, dew-point 11.2 deg C, relative
humidity 32%.

Don't dismiss it though. A blip like that might be a resource for geo-physics when the next generation replaces this lot of sheeple.

Hello Hugh. I'm afraid that your instrument is telling porkies. Make sure
all your connections are sound, and the battery, if it uses one, is good. If
you use a radio link, check the receiver unit too. RH below 20% is quite
rare. My lowest value in the past 17 years is 13% in May 2013. The average
lowest per month ranges from 53% in December to 26% in April.

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html

"Hugh Newbury" wrote in message
...
Early this morning (0450) the humidity recorded by my AWS was 3%, the
DP -29.6.

I suppose everyone's figures were similar? So what caused this surely
exceptionally low figure? Simply the Spanish or Saharan plume?

Hugh

--

Hugh Newbury

www.evershot-weather.org

Hello Hugh. I'm afraid that your instrument is telling porkies. Make sure
all your connections are sound, and the battery, if it uses one, is good. If
you use a radio link, check the receiver unit too. RH below 20% is quite
rare. My lowest value in the past 17 years is 13% in May 2013. The average
lowest per month ranges from 53% in December to 26% in April.

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html

I strongly suspect so.

According to Robin Sterling's "The Weather in Britain", the lowest RH on record in the UK is 4%, at both Ringway and Great Dun Fell on 29 March 1965. Here's the synoptic chart:

http://i.imgur.com/UVS59Di.gif

However, I think that these are suspect as well, and the 8% alleged at Altnaharra on 18 February 2003 has since been discredited.

In "Weather" Vol 56, June 2001, Stephen Burt lists the lowest relative humidities in the UK since 1880, and has the very lowest as 9.5% at Parkstone, Dorset, on 24 May 1901 (citation: Hawke, 1944).

http://onlinelibrary.wiley.com/doi/1....tb06569.x/pdf

Synoptics:

http://imgur.com/55GoPKq

More recently there were relative humidities widely below 20% on 18 June 2000.

http://imgur.com/wg2mli3

The lowest was 11.5% at Brize Norton with a dry bulb temperature of 29.5 deg C and a dew point of -3.5 deg C at 16:00 UTC.

This is fourth lowest relative humidity in the UK record since 1800, equal with Parkstone again. In fact Parkstone appears three times in the top four.

Stephen.

On 24/07/14 18:36, Bernard Burton wrote:
Hello Hugh. I'm afraid that your instrument is telling porkies. Make sure
all your connections are sound, and the battery, if it uses one, is good. If
you use a radio link, check the receiver unit too. RH below 20% is quite
rare. My lowest value in the past 17 years is 13% in May 2013. The average
lowest per month ranges from 53% in December to 26% in April.


Bernard, Thanks so much for your help and advice. That's exactly what
this group does best, helping an amateur.

Hugh

Bernard Burton wrote:
Hello Hugh. I'm afraid that your instrument is telling porkies. Make sure
all your connections are sound, and the battery, if it uses one, is good. If
you use a radio link, check the receiver unit too. RH below 20% is quite
rare. My lowest value in the past 17 years is 13% in May 2013. The average
lowest per month ranges from 53% in December to 26% in April.

------------------------------
Was that May 3rd 2013 Bernard? I got 19% at 16.30 which is my record.
Dave

Bernard, Thanks so much for your help and advice. That's exactly what
this group does best, helping an amateur.

Hugh
---------------------------------------------------
Well said Hugh, I agree. Despite some leaving and a few trying to spoil
it I am so glad there are still several contributors who are there to
observe, help and inform and enjoy weather comments. Makes sticking it
out worth it.
I seem to remember from a couple of years back you had a Watson type
station similar to mine? If so, whilst they are capable of some
excellent and accurate measurements, they do occasionally have their
"funny half hours" ! I tend to find one of the following fixes most things.
1. Reboot of PC
2. Shutdown software (Cumulus?) and restart
3. Disconnect and reconnect USB lead
4. Check batteries in sender unit (and console although they seem to
last forever)
5. Check connections of leads although not really applicable to humidity
as this is sent directly wirelessly from the sensor.

Good luck,
Dave