December Down the Ages

This forum is for comments about the weather spanning several days, developing phenomena eg drought, comparisons with previous years, local climatic features eg Cheshire Gap showers, and anything that does not fit any of the other forums.

December Down the Ages

Postby Darren Rogers » 2014 Dec 09, 22:00

Over the last few months on the 'Weather On-line' website Philip Eden has had monthly articles regarding the weather 'down the ages' for that particular month - as yet the site has not been updated with a 'December down the ages'.
However, when it does, I suspect that Philip may make comment on the fact that December is a month that is generally unaffected by global warming.
Does anyone know or have any theories as to why this may be so?

Using the Newton Rigg (Penrith) data we have the following by way of example (digital records commence 1914 with the 1920's and 40's incomplete):
1914-1919 = 3.23c
1930's = 3.34c
1951-59 = 4.25c
1960's = 2.31c
1970's = 4.02c
1980's = 3.94c
1990's = 3.48c
2000's = 3.58c
2010-13 = 2.81c

ALSO - and I'm thinking UK mountain sites, does anyone know if the affect of GW remains constant or slower/increased at altitude within the UK?
Darren Rogers
Maulds Meaburn
Cumbria (Half way between Shap and Appleby)

http://www.mauldsmeaburnweather.co.uk
Darren Rogers
 
Posts: 145
Joined: 2011 Nov 27, 20:22
Location: Cumbria - half way between Shap and Appleby in the Eden valley

Re: December Down the Ages

Postby greg_gruner » 2014 Dec 10, 10:35

Hi Darren
yes, I noticed that December anomaly looking at the data for Wokingham as well. When the 30-year reference averages changed from 1971-2000 to 1981-2010 December was the only month to show a fall in temperature. Some of that drop, though not all of it, could be attributed to the record-breaking December 2010.
I'm sure this would be a good research project, but my hunch is that it is something to do with the jet stream and the stratosphere and possibly arctic ice cover. If GW has caused some shift in upper level patterns, it may be that December is now more open to incursions of cold air. Certainly as far as my childhood memories go (not scientific, of course!) I remember mild Decembers generally in the 70s, but colder weather later in the winter (with Easter often colder than Christmas).
As for GW and altitude, that would really depend on whether the air mass frequencies have changed. The lapse rate is generally high in polar maritime air and low in tropical maritime air. So again, if December is more open to polar maritime air masses, that may have more effect at altitude.
Greg
Greg Gruner
Farnborough, Hampshire
greg_gruner
 
Posts: 224
Joined: 2012 Feb 04, 17:28

Re: December Down the Ages

Postby Darren Rogers » 2014 Dec 11, 17:09

weather online has now updated with Philip's 'December Down the ages' and there is a section on this thread:

The mean December temperature, according the Professor Gordon Manley's Central England Temperature (CET) record, was 3.9°C during the eighteenth century, 4.0°C in the nineteenth, and 4.7°C during the twentieth century. The average for the standard reference period 1981-2010 was 4.7°C, apparently showing a stalled warming. But that warming process in December has been very erratic. The warmest decades of all were the 1970s and 1980s but these followed a run of cold Decembers in the 1960s; meanwhile the 1990s and 2000s brought several colder months including 2010, the coldest December since 1890.
Darren Rogers
Maulds Meaburn
Cumbria (Half way between Shap and Appleby)

http://www.mauldsmeaburnweather.co.uk
Darren Rogers
 
Posts: 145
Joined: 2011 Nov 27, 20:22
Location: Cumbria - half way between Shap and Appleby in the Eden valley

Re: December Down the Ages

Postby Graham Easterling » 2014 Dec 12, 19:35

I've just checked December averages for Penzance, and it is certainly significantly different than for any other month.

1961-1990 8.0C
1981-2010 7.8C
The only month where the mean temperature did not rise during this period apart from November, when it remained the same. So it would appear the late Autumn-early winter temperature rise has stalled.

Taking the entire year:-
1961-1990 11.1C
1981-2010 11.6C

There has also been a marked decrease in gales during recent years.
In Penzance:-
1993-1999 averaged 3.9 gales in November & December combined.
2000-2013 averaged 2.4 gales

Penzance is, of course, very sheltered by west Cornwall standards. Exposed nearby areas average over 20 gales a year, the highest lowland figures anywhere in England & Wales.
Graham

Penzance Weather Station
Grid Ref:
SW464231 - Post Code: TR18 4TP
19m AMSL - Aspect SSE
In a SE - NW orientated valley

23 Years of Penzance Weather Records : http://penzanceweather.atspace.com/weather.html
Graham Easterling
 
Posts: 316
Joined: 2011 Nov 30, 20:29
Location: Penzance, Cornwall

Re: December Down the Ages

Postby Darren Rogers » 2014 Dec 13, 10:35

Still using the Newton Rigg data I looked at some other comparisons and found:

months of the year colder in the decade of 2000-09 than they were in the 1970's = OCT + DEC.

months of the year colder in the decade of 2000-09 than they were in the 1960's = OCT

Months of the year (other than Oct+Dec) to show no appreciable difference in temp from 1970's to this century = AUG - with a slight case for June
Darren Rogers
Maulds Meaburn
Cumbria (Half way between Shap and Appleby)

http://www.mauldsmeaburnweather.co.uk
Darren Rogers
 
Posts: 145
Joined: 2011 Nov 27, 20:22
Location: Cumbria - half way between Shap and Appleby in the Eden valley


Return to Everything Else Weatherwise



Who is online

Users browsing this forum: No registered users and 1 guest

cron