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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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#1
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.... a bit 'left-field' this one but someone's bound to know.
Is there a word (or short phrase) that explicitly covers the situation we seem to have had many times this winter in this neck of the woods of 'upside-down' 24hr temperature profiles. By that I mean the *maximum* in the standard (09-09Z) period occurs overnight, and the minimum in the same period is often at the *start* of the 24hr (09Z). We've had five such this month already, and no less than nine where the minimum temperature has occurred the previous 09Z (rather than in the few hours leading up to today's 09Z). It would be nice to have a tally of such events but what do I call the 'event' in short? Martin. -- West Moors / East Dorset Lat: 50deg 49.25'N, Long: 01deg 53.05'W Height (amsl): 17 m (56 feet) COL category: C1 overall |
#2
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Martin Rowley scrive:
Is there a word (or short phrase) that explicitly covers the situation we seem to have had many times this winter in this neck of the woods of 'upside-down' 24hr temperature profiles. You might call it an inverse oriel ;-) -- Gianna Peterhead, Scotland buchan-meteo.org.uk |
#3
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It would be nice to have a tally of such events but what do I call the
'event' in short? Advection-dominated diurnal profile (as opposed to radiation)? Clumsy, but true ![]() -- Freddie Bayston Hill Shropshire 102m AMSL http://www.hosiene.co.uk/weather/cumulus/ |
#4
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On Jan 20, 2:46*pm, Martin Rowley
wrote: ... a bit 'left-field' this one but someone's bound to know. Is there a word (or short phrase) that explicitly covers the situation we seem to have had many times this winter in this neck of the woods of 'upside-down' 24hr temperature profiles. By that I mean the *maximum* in the standard (09-09Z) period occurs overnight, and the minimum in the same period is often at the *start* of the 24hr (09Z). We've had five such this month already, and no less than nine where the minimum temperature has occurred the previous 09Z (rather than in the few hours leading up to today's 09Z). It would be nice to have a tally of such events but what do I call the 'event' in short? Martin. -- West Moors / East Dorset Lat: 50deg 49.25'N, Long: 01deg 53.05'W Height (amsl): 17 m (56 feet) COL category: C1 overall I think I would just call it an 'inverse diurnal', Martin, although, like you, I am unaware of any generally accepted term. Dick Lovett Charlbury (Oxfordshire Cotswolds) 122m |
#5
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On Jan 20, 2:46 pm, Martin
wrote: Is there a word (or short phrase) that explicitly covers the situation we seem to have had many times this winter in this neck of the woods of 'upside-down' 24hr temperature profiles. By that I mean the *maximum* in the standard (09-09Z) period occurs overnight, and the minimum in the same period is often at the *start* of the 24hr (09Z). [and] On 20/01/2012 17:57, Dick wrote: I think I would just call it an 'inverse diurnal', Martin, although, like you, I am unaware of any generally accepted term. Dick Lovett Charlbury (Oxfordshire Cotswolds) 122m .... yes, thanks Dick - that was I admit my first thought; I realised 'inverse' would probably come into it, but was trying to avoid 'diurnal' : we meteorologists use the word as a short hand for low temps overnight/higher temps daytime, but the strict definition of 'diurnal' is (COD) ... " of the day, not nocturnal (Astron); occupying one day; daily, of each day (Zool) active in daytime .... (etc), which isn't really specific enough for *our* idea of the 'average' temperature curve. It would then mean that we'd have to add 'average' or 'normal' before 'diurnal', so we'd then be getting something like 'inverse average diurnal' which is getting long-winded. Could use 'atypical' of course, but that again isn't specific enough; many 24hr temperature curves are non-typical, yet don't always meet the specific criteria as above. It's more than just an academic exercise: the number of instances of 'X' (whatever its called) is related to the departure of the 12hr average extremes from the 24hr average extremes. For example, this month (January) using Hurn data, the current 24hr average minimum is 2.9 against 4.0 for the 18-06 mean & the 24hr average maximum is 10.9 vs. 10.4 for the 06-18Z. We've now had 9 such events so far this month. In a more 'typical' month, with no, or just one or two, events then the difference is close to zero, and not usually more than 0.2degC. Martin. -- West Moors / East Dorset Lat: 50deg 49.25'N, Long: 01deg 53.05'W Height (amsl): 17 m (56 feet) COL category: C1 overall |
#6
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![]() It's more than just an academic exercise: the number of instances of 'X' (whatever its called) is related to the departure of the 12hr average extremes from the 24hr average extremes. For example, this month (January) using Hurn data, the current 24hr average minimum is 2.9 against 4.0 for the 18-06 mean & the 24hr average maximum is 10.9 vs. 10.4 for the 06-18Z. We've now had 9 such events so far this month. In a more 'typical' month, with no, or just one or two, events then the difference is close to zero, and not usually more than 0.2degC. Martin. -- West Moors / East Dorset Lat: 50deg 49.25'N, Long: 01deg 53.05'W Height (amsl): 17 m (56 feet) COL category: C1 overall Martin, I managed to 'dig out' an old copy of a Met Office 'Climatological Memoranda' dealing with mean and extreme temperatures over the UK. It has a section dealing with the differences between 24 hour (09-09) max & min temperatures and 12 hour (09-21) day max & (21-09) night min. The results, following an investigation of 38 stations between 1957 and 1970, show that, on average, in January and December the 24 hour Max is 0.3 to to 0.4C higher than the 12 hour day max. The differences for minima show that 24 hour minima were typically 0.7C lower than the 12 hour (21-09) value during the same two months. Dick |
#7
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On Jan 22, 11:44*am, Dick wrote:
It's more than just an academic exercise: the number of instances of 'X' (whatever its called) is related to the departure of the 12hr average extremes from the 24hr average extremes. For example, this month (January) using Hurn data, the current 24hr average minimum is 2.9 against 4.0 for the 18-06 mean & the 24hr average maximum is 10.9 vs. 10.4 for the 06-18Z. We've now had 9 such events so far this month. In a more 'typical' month, with no, or just one or two, events then the difference is close to zero, and not usually more than 0.2degC. I managed to 'dig out' an old copy of a Met Office 'Climatological Memoranda' dealing with mean and extreme temperatures over the UK. It has a section dealing with the differences between: 24 hour (09-09) max & min temperatures and 12 hour (09-21) day max & (21-09) night min. The results, following an investigation of 38 stations between 1957 and 1970, show that, on average, in January and December the 24 hour Max is: 0.3 to to 0.4C higher than the 12 hour day max. The differences for minima show that: 24 hour minima were typically 0.7C lower than the 12 hour (21-09) value during the same two months. Meaning? |
#8
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On 22/01/2012 19:11, Weatherlawyer wrote:
On Jan 22, 11:44 am, wrote: It's more than just an academic exercise: the number of instances of 'X' (whatever its called) is related to the departure of the 12hr average extremes from the 24hr average extremes. For example, this month (January) using Hurn data, the current 24hr average minimum is 2.9 against 4.0 for the 18-06 mean& the 24hr average maximum is 10.9 vs. 10.4 for the 06-18Z. We've now had 9 such events so far this month. In a more 'typical' month, with no, or just one or two, events then the difference is close to zero, and not usually more than 0.2degC. I managed to 'dig out' an old copy of a Met Office 'Climatological Memoranda' dealing with mean and extreme temperatures over the UK. It has a section dealing with the differences between: 24 hour (09-09) max& min temperatures and 12 hour (09-21) day max& (21-09) night min. The results, following an investigation of 38 stations between 1957 and 1970, show that, on average, in January and December the 24 hour Max is: 0.3 to to 0.4C higher than the 12 hour day max. The differences for minima show that: 24 hour minima were typically 0.7C lower than the 12 hour (21-09) value during the same two months. Meaning? Meaning that if you have a really cold night it is likely to count for 2 days instead of only 1 if you only read your min-max thermometer at 0900 each day. This is because for much of the winter under clear skies the minimum temperature will be only an hour or so before that time (around or just after sunrise after all the night's cooling). If you read your min-max thermometer twice each day, at 0900 and 2100, the rise in temperature during the day will most likely cancel out the preceding cold night. Below are a recent set of my recorded minima (non-standard exposure, but that doesn't really matter for this illustration). These are taken by re-setting the maximum and minimum indices at times as close to 0700 and 1900 as my social routine will allow, the maximum being 0700 to 1900 and the minimum 1900 to 0700 *except* that if the temperature is still falling at 0700 or still rising at 1900 then the minimum or maximum reached in the next 12 hour period will be the one recorded. I call this the "arithmetic" maximum and minimum as it is as far as possible the values you would get from looking at a graph of the day's temperature. Jan 2012 12 0.2 13 -4.7 14 -7.8 15 2.3 16 -6.6 17 -7.9 18 -3.5 19 8.6 If I had just used the 0900 values each day, this same data set could very well have been: Jan 2012 12 0.2 13 -4.7 14 -7.8 15 *-6.5* 16 -6.6 17 -7.9 18 *-5.7* 19 *7.0* The three marked with * are now much lower than before because the temperature had hardly started to rise after the previous cold night. In the case of 19th Jan, which was a really mild night, the "0900-0900" recorded minimum could actually have been much lower than the 7.0C I have put in because you might have picked up the tail end of the 17 / 18 cold night and not the 18/19 mild night. As it happened, the mild air arrived in time to send the temperature well above freezing by 0700 on 18th in spite of the frost earlier in the night. The potential size of this effect is such that it could have to be taken into account when comparing temperature records or looking for long-term trends. The "true" or "arithmetic" mean will actually give you the highest minimum temperatures - if a cold day is followed by a mild night then there will be cases when the 12-hour periods interpreted exactly and without the "allowance" I make will also give lower minima that my methods, but not so low as the "24 hour" protocol. In the summer part of the year, the minimum temperature would be expected to be many hours before the 0900 standard, allowing the rise in temperature by then to effectively "re-set" the minimum record and so greatly reduce this error. As can be seen, the magnitude of this difference between protocols will vary both by season of the year and by weather type, so quoting an annual figure for the difference is pretty much meaningless. Now we have continuously recording thermometers widely available, some thought may need to be given as how to properly define the maximum and minimum temperatures, given that the "traditional" definition appears to be rather wanting. Over to those who collect and analyse such records... -- - Yokel - Yokel posts via a spam-trap account which is not read. |
#9
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On Jan 20, 2:52*pm, Buchan Meteo wrote:
Martin Rowley scrive: Is there a word (or short phrase) that explicitly covers the situation we seem to have had many times this winter in this neck of the woods of 'upside-down' 24hr temperature profiles. You might call it an inverse oriel ;-) -- Gianna Peterhead, Scotland buchan-meteo.org.uk Every time I see the explanation which has 366 rotations in 365 days it makes me shake my head,I wonder what happens when they encounter the leap year from Mar 1st 2011 until Feb 29th 2012 which have 366 days in it ! - http://adsabs.harvard.edu/full/1904PA.....12..649B So we have a Harvard/NASA explanation while the center of discussion here is daily temperature fluctuations which would occur within a 24 period where local influences dominate the normal response of temperature rises and falls due to the rotation of the Earth 1461 times across 4 years. No offence,you would have to be a bunch of dummies to go along with 366 rotations in 365 days and I am not talking about the ability to remain silent,if anger or intense irritation is not present then there must be tumbleweeds going through your minds. Anyone want to predict that temperatures will fall and rise within the next 24 hours and the cause behind it ?,I wouldn't count on the NASA/ Harvard explanation which is merely an extension of the one that was conceived in the late 17th century U.K.. |
#10
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On Jan 22, 7:50*pm, Yokel wrote:
On 22/01/2012 19:11, Weatherlawyer wrote: On Jan 22, 11:44 am, *wrote: It's more than just an academic exercise: the number of instances of 'X' (whatever its called) is related to the departure of the 12hr average extremes from the 24hr average extremes. For example, this month (January) using Hurn data, the current 24hr average minimum is 2.9 against 4.0 for the 18-06 mean& *the 24hr average maximum is 10.9 vs. 10.4 for the 06-18Z. We've now had 9 such events so far this month. In a more 'typical' month, with no, or just one or two, events then the difference is close to zero, and not usually more than 0.2degC. I managed to 'dig out' an old copy of a Met Office 'Climatological Memoranda' dealing with mean and extreme temperatures over the UK. It has a section dealing with the differences between: 24 hour (09-09) max& *min temperatures and 12 hour (09-21) day max& *(21-09) night min. The results, following an investigation of 38 stations between 1957 and 1970, show that, on average, in January and December the 24 hour Max is: 0.3 to to 0.4C higher than the 12 hour day max. The differences for minima show that: 24 hour minima were typically 0.7C lower than the 12 hour (21-09) value during the same two months. Meaning? Meaning that if you have a really cold night it is likely to count for 2 days instead of only 1 if you only read your min-max thermometer at 0900 each day. *This is because for much of the winter under clear skies the minimum temperature will be only an hour or so before that time (around or just after sunrise after all the night's cooling). Arrrrgh!!! Beware the trapses. Nobody loves us. We wants it, we needs it. Must have the precious. They stole it from us. Sneaky little weathermen. No. Not masters... Yes, ...precious, ...false! They will cheat you, hurt you. LIE!! If you read your min-max thermometer twice each day, at 0900 and 2100, the rise in temperature during the day will most likely cancel out the preceding cold night. Below are a recent set of my recorded minima (non-standard exposure, but that doesn't really matter for this illustration). *These are taken by re-setting the maximum and minimum indices at times as close to 0700 and 1900 as my social routine will allow, the maximum being 0700 to 1900 and the minimum 1900 to 0700 *except* that if the temperature is still falling at 0700 or still rising at 1900 then the minimum or maximum reached in the next 12 hour period will be the one recorded. *I call this the "arithmetic" maximum and minimum as it is as far as possible the values you would get from looking at a graph of the day's temperature.. Jan 2012 12 * *0.2 13 * *-4.7 14 * *-7.8 15 * *2.3 16 * *-6.6 17 * *-7.9 18 * *-3.5 19 * *8.6 If I had just used the 0900 values each day, this same data set could very well have been: Jan 2012 12 * *0.2 13 * *-4.7 14 * *-7.8 15 * **-6.5* 16 * *-6.6 17 * *-7.9 18 * **-5.7* 19 * **7.0* The three marked with * are now much lower than before because the temperature had hardly started to rise after the previous cold night. In the case of 19th Jan, which was a really mild night, the "0900-0900" recorded minimum could actually have been much lower than the 7.0C I have put in because you might have picked up the tail end of the 17 / 18 cold night and not the 18/19 mild night. *As it happened, the mild air arrived in time to send the temperature well above freezing by 0700 on 18th in spite of the frost earlier in the night. The potential size of this effect is such that it could have to be taken into account when comparing temperature records or looking for long-term trends. *The "true" or "arithmetic" mean will actually give you the highest minimum temperatures - if a cold day is followed by a mild night then there will be cases when the 12-hour periods interpreted exactly and without the "allowance" I make will also give lower minima that my methods, but not so low as the "24 hour" protocol. In the summer part of the year, the minimum temperature would be expected to be many hours before the 0900 standard, allowing the rise in temperature by then to effectively "re-set" the minimum record and so greatly reduce this error. *As can be seen, the magnitude of this difference between protocols will vary both by season of the year and by weather type, so quoting an annual figure for the difference is pretty much meaningless. Now we have continuously recording thermometers widely available, some thought may need to be given as how to properly define the maximum and minimum temperatures, given that the "traditional" definition appears to be rather wanting. *Over to those who collect and analyse such records.... Those who are going to be analysing such records will have been onto that as soon as they went digital; I assume it was a fair bit ago. Unfortunately they will have probably given that bone to the bods in back rooms in East Anglia. Pity that. For those that do manage to view their data from the night time, I hope you will pay it more attention. You don't have any friends; Nobody likes you! I'm not listening... I'm not listening... Master looks after us now. We don't need you ...anymore. |
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