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Air Frosts 09/10


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Posted
  • Location: Nr Appleby in Westmorland
  • Location: Nr Appleby in Westmorland

Judging by the forecast for the week coming up, and by the fact that there have only been two occasions when I've had air frosts beyond this date (May 19th 2008 and June 2nd 2001) I'm fairly confident that the final figures are in for the autumn/winter/spring period, with a final total of 91 nights of air frost. This is far more than previously recorded:-

2008/09 - 69

2007/08 - 59

2006/07 - 39

2005/09 - 74

2004/05 - 56

2003/04 - 72

2002/03 - 53

2001/02 - 62

2000/01 - 72

I don't know what this proves other than it was bloody cold, and that I rather neatly had 133% more air frosts last winter than I did in 2006/07.

Does anyone else have their total air frosts? I suspect Coleraine will have had 92.

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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

77 air frosts here October 2009- May 15th 2010.

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Posted
  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral

26 here, usually we get between 10-15 or so, so this year was much worse than normal

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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

60 air frosts here, the last being only several days ago. 60 is more than normal.

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Posted
  • Location: South Derbyshire nr. Burton on Trent, Midlands, UK: alt 262 feet
  • Weather Preferences: Extreme winter cold,heavy bowing snow,freezing fog.Summer 2012
  • Location: South Derbyshire nr. Burton on Trent, Midlands, UK: alt 262 feet

The last air frost recorded here was May 13th, though I don’t normally finalise my data until June.

Since local records began here in 1991, this air frost season is running in second place with a total of 65, next to a total of 74 in 1995/ 96.

I would say it’s forgone conclusion that 95/ 96 will keep it’s crown, unless something dramatic happens.

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Posted
  • Location: Derbyshire Peak District. 290 mts a.s.l.
  • Weather Preferences: Anything extreme
  • Location: Derbyshire Peak District. 290 mts a.s.l.

63 air frosts here this season and very unlikely there will be any more. This figure compares to 54 in 2008/09 and is equal with 1994/95 but well behind several other seasons.1995/96 had 71, 1985/86 had 79, 1986/87 had 84 and top of the list was 1978/79 with 100.

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Posted
  • Location: Southsea, Portsmouth on the Costa Del Solent
  • Location: Southsea, Portsmouth on the Costa Del Solent

We had 11 air frosts here (temperatures below 0C) with the last one being on January 30th. Normally we would only have a couple of nights just below freezing each winter.

We also had 43 ground frosts (temperatures down to at least 3C) quite remarkable to have that many here as well. The last ground frost here was on March 10th.

Temperatures have not gone below 5C here since March 31st.

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Posted
  • Location: G.Manchester
  • Location: G.Manchester

October 2009; 1

November 2009; 0

December 2009; 12

January 2010; 13

February 2010; 8

March 2010; 7

April 2010; 6

Total 47

2008/2009

October 2008; 3

November 2008; 4

December 2008; 11

January 2009; 13

February 2009; 9

March 2009; 9

April 2009; 2

Total 51

2006/2007

October 2006; 0

November 2006; 6

December 2006; 5

January 2007; 3

February 2007; 8

March 2007; 6

April 2007; 1

Total 29

More frosts in 2008/2009 but the much milder period outweighed the temperature anom. Less frosts in 2009/2010 but it was persistantly colder.

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Posted
  • Location: Dundee
  • Weather Preferences: Snow, thunderstorms, gales. All extremes except humidity.
  • Location: Dundee

66 air frosts here over the winter. Didn't add any in May though got down to 0.1C twice with a further two nights sub 1C. The nearby Met O station at Invergowrie did record one airfrost [just] on one of those nights.

A bit surprised to see that 66 was only four more than that recorded in 2008/9 which had 62, double that of the 31 in 2007/8. There must have been a lot more slight frosts in 2008/9 as it certainly did not appear to feel anything like as cold as last Winter.

The Highland valleys must have recorded 100+ this Winter I would imagine.

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Posted
  • Location: North York Moors
  • Location: North York Moors

57 here, only one in November and that was the very last day.

Only 10 miles from North Sea, so not especially frost prone at least in first part of winter.

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

63 air frosts here this season and very unlikely there will be any more. This figure compares to 54 in 2008/09 and is equal with 1994/95 but well behind several other seasons.1995/96 had 71, 1985/86 had 79, 1986/87 had 84 and top of the list was 1978/79 with 100.

Very suprised to see this year equalling 94/95 which in the main was very mild and unsettled - did you mean to say 84/85?

Looks like 95/96 for many saw slightly more frosts, largely I suspect due to the cold March and May and also first half to December.

Certainly a notably frosty winter here in Cumbria, I think we managed an air frost nearly every day between the 17th Dec and 15th Jan, and the first half of March saw many frosts. Feb saw many nights just at or above 0 degrees, had it been slightly colder I think we would easily have beaten 95/96 figures.

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Posted
  • Location: Skirlaugh, East Yorkshire
  • Location: Skirlaugh, East Yorkshire

There were 45 air frosts here in 2009/10 (1971-2000 average is 25):

December: 10

January: 14

February: 11

March: 10

This compares to the following in past years:

2008/09: 21

2007/08: 13

2006/07: 11

2005/06: 37

2004/05: 25

2003/04: 26

2002/03: 29

2001/02: 18

2000/01: 35

1999/00: 19

1998/99: 22

1997/98: 14

1996/97: 29

1995/96: 44

1994/95: 28

1993/94: 28

1992/93: 34

1991/92: 29

1990/91: 30

1989/90: 14

1988/89: 17

1987/88: 20

1986/87: 43

1985/86: 50

1984/85: 49

1983/84: 24

1982/83: 24

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Posted
  • Location: Newton Aycliffe, County Durham
  • Location: Newton Aycliffe, County Durham

I'd just like to point out to the person that said about air frosts (below 0.0) is that 0.0ºC is also an air frost. It does not need to be BELOW freezing to be an air frost it needs to be 0.0c OR below.

One or two people may have a seasonal miscount due to this.

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Posted
  • Location: Derbyshire Peak District. 290 mts a.s.l.
  • Weather Preferences: Anything extreme
  • Location: Derbyshire Peak District. 290 mts a.s.l.

I'd just like to point out to the person that said about air frosts (below 0.0) is that 0.0ºC is also an air frost. It does not need to be BELOW freezing to be an air frost it needs to be 0.0c OR below.

One or two people may have a seasonal miscount due to this.

I think you may need to re-count your air frosts Paul. 0.0c does not count as an air frost, the temp' has to be -0.1c or lower.

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Posted
  • Location: Rugby, Warks
  • Weather Preferences: Dangerous
  • Location: Rugby, Warks

I have nothing to compare these figures to as this is my first full season of a frost recordings. But i'll be very interested to see if future years come close.

Dec 09: 16

Jan 10: 17

Feb 10: 12

Mar 10: 9

Apr 10: 1

May 10: 1

Total: 56

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Posted
  • Location: Newton Aycliffe, County Durham
  • Location: Newton Aycliffe, County Durham

I think you may need to re-count your air frosts Paul. 0.0c does not count as an air frost, the temp' has to be -0.1c or lower.

0.0ºc is the temperature that water freezes, not -0.1.

0.0ºc is freezing point, and defines when liquid water turns to ice and when dew turns to ground frost.

0.0ºc (air temperature) is also, meteorologically speaking, therefore an airfost. Obviously. Freezing is freezing, not just below.

We've all had this conversation before, and I was right then, too.

Google it up if you don't believe me - not that anybody should need to, we all know what defines freezing point right? And air and ground frost is defined upon freezing point.

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Posted
  • Location: Newton Aycliffe, County Durham
  • Location: Newton Aycliffe, County Durham

I'd just like to add that a quick Google sees most online answer sites and wikipedia etc, defining an airfrost as below 0.0º. However that does not make them right.

They either do not know what they are talking about, or are too lazy to define frost properly, which should be "when the air/ground temperature is at 0.0º or below then an air/ground frost is recorded"

To me defining airfrost as "when the air temperature falls below 0c" is just a lazy explanation for the layman, as well as being technically incorrect.

Luckily for me, BBC Weather are on my side http://www.bbc.co.uk/weather/features/understanding/frost.shtml

Clearly defined on the link provided as "When the temperature in the Stephenson screen reaches zero, there is said to be an 'air frost'."

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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

All this for 0.1c :)

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Posted
  • Location: Newton Aycliffe, County Durham
  • Location: Newton Aycliffe, County Durham

Well at the end of the day it could make a difference to the figures.

You may be asked how many days did you go below zero, to which you might answer "29" because 29 is the amount of minus minimums that you had, but if somebody asks how many air frosts your answer may be "30".

There is a difference between air frosts and days below zero, people often forget or don't know that.

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Posted
  • Location: Derbyshire Peak District. 290 mts a.s.l.
  • Weather Preferences: Anything extreme
  • Location: Derbyshire Peak District. 290 mts a.s.l.

I'd just like to add that a quick Google sees most online answer sites and wikipedia etc, defining an airfrost as below 0.0º. However that does not make them right.

They either do not know what they are talking about, or are too lazy to define frost properly, which should be "when the air/ground temperature is at 0.0º or below then an air/ground frost is recorded"

To me defining airfrost as "when the air temperature falls below 0c" is just a lazy explanation for the layman, as well as being technically incorrect.

Luckily for me, BBC Weather are on my side http://www.bbc.co.uk/weather/features/understanding/frost.shtml

Clearly defined on the link provided as "When the temperature in the Stephenson screen reaches zero, there is said to be an 'air frost'."

As far as the Met' Office are concerned, and the World Meteorological Organisation, an air frost is when the temperature falls to -0.1c or lower. 0.0c may be the generally accepted temperature at which water freezes but in reality it's also the temperature at which ice begins to melt.

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Posted
  • Location: South Derbyshire nr. Burton on Trent, Midlands, UK: alt 262 feet
  • Weather Preferences: Extreme winter cold,heavy bowing snow,freezing fog.Summer 2012
  • Location: South Derbyshire nr. Burton on Trent, Midlands, UK: alt 262 feet

As far as the Met' Office are concerned, and the World Meteorological Organisation, an air frost is when the temperature falls to -0.1c or lower. 0.0c may be the generally accepted temperature at which water freezes but in reality it's also the temperature at which ice begins to melt.

Hi TM,

Also this link may help others to understand the complications of 0.0c, the melting point and freezing point of water.

'At the right is a container of water with an ice cube in it. The water and ice are at 0°C, which is the melting point of ice and the freezing point of water.

Molecules of ice are constantly escaping into the water (melting), and molecules of water are being captured on the surface of the ice (freezing).

When the rate of freezing is the same as the rate of melting, the amount of ice and the amount of water won't change. The ice and water are said to be in dynamic equilibrium with each other. The ice is melting, and the water is freezing, but both are occurring at the same rate, so there is no net change in either quantity.

This balance will be maintained as long as the water stays at 0°C, or unless something happens to favour one of the processes over the other.'

http://www.worsleyschool.net/science/files/saltandfreezing/ofwater.html

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LOL.... why so much arguing over 0.1C even if 0.0C wasn't an air frost, thermometers and their positioning could make them 0.5C to 1C warmer than the actual temperature is anyway.

This from weatheronline from this morning still going for frosts this week, GFS 00Z i think is on its own in not bringing the cooler air properly south, all other runs do.

Issued: 08:15hrs Sunday 23th May 2010

Simon: Gardeners beware! We are not out of the woods just yet. With northerly winds bringing cooler conditions southwards through the country this week, the threat of a slight ground frost returns. Keep a careful eye on the forecast throughout the coming days.

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