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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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#11
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#12
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On Friday, November 11, 2016 at 5:26:40 PM UTC, wrote:
Having just read the piece on observation timing on the FAQ pages, I wanted to see what the majority do with regards timings. 10 or so years ago, as a teenager with admittedly not much of an eye for detail, I used to take my readings at 1800 local time each day, noting the max/mins for the previous 24 hours. However, having had a little look on various sites I see 0900 local seems to be a more common time, along with splitting the climatological day into two periods. Or is a "normal" day seen as acceptable (00-24 local)? Thanks, Luke If you want to align with WMO standards 09-09h is the correct way to do it! So many weather station these days use the period 0000-2400, which does make more sense. An example of how errors occur with 09-09h is when minimum temperatures occur before midnight. If for arguments sake a minimum of -2.5C occurs at 2300 this would go down as on the day it occur ed. However on the 09-09 time period a minimum at this time would be recorded on the following day if -2.5C was the minimum. (minimum between 2100-0900h) This situation occurs quite frequently during the winter months! |
#13
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I've always thought it a bit daft when recording 09-09 that particularly
In winter your 09 obs of for example -2C is quite often your min for the next 09-09 period if there is a change to a milder airmass. 2 air frost days for the price of 1. Ian Raunds E Northants |
#14
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Ian wrote:
I've always thought it a bit daft when recording 09-09 that particularly In winter your 09 obs of for example -2C is quite often your min for the next 09-09 period if there is a change to a milder airmass. 2 air frost days for the price of 1. The same can happen with 00-24. On Friday night for example the temp dropped below zero here before midnight before much milder air moved in around 00:30. 2 air frosts when the temp was only sub zero for a couple of hours. -- Brian Wakem Lower Bourne, Farnham, Surrey http://www.brianwakem.co.uk/weather Live obs @ 09:11:00 : 5.9C, DP 5.9C, RH 100%, 0.2 mm |
#15
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Ian wrote:
I've always thought it a bit daft when recording 09-09 that particularly In winter your 09 obs of for example -2C is quite often your min for the next 09-09 period if there is a change to a milder airmass. 2 air frost days for the price of 1. Ian Raunds E Northants The same sort of thing happens no matter what recording period you use. For example, if there is a very short period of air frost from 2330 till 0030 that would only count as 1 air frost day if using the 09-09 recording period but it would count as 2 air frost days if you use the 00-24 recording period. Indeed a single night of air frost lasting, say, from 2000 till 0800 would count as 1 air frost day in the 0900-0900 recording system but would count as 2 days in the 0000-2400 system, even though there was actually only one night of air frost. No system is perfect. The important thing is to have a system and stick to it so that there is internal consistency withing your own set of observations. Strictly speaking, comparison with surrounding "official" stations is valid only if you use the 0900-0900 GMT recording period. -- Norman Lynagh Tideswell, Derbyshire 303m a.s.l. http://peakdistrictweather.org @TideswellWeathr |
#16
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On Friday, 11 November 2016 17:26:40 UTC, wrote:
Having just read the piece on observation timing on the FAQ pages, I wanted to see what the majority do with regards timings. 10 or so years ago, as a teenager with admittedly not much of an eye for detail, I used to take my readings at 1800 local time each day, noting the max/mins for the previous 24 hours. However, having had a little look on various sites I see 0900 local seems to be a more common time, along with splitting the climatological day into two periods. Or is a "normal" day seen as acceptable (00-24 local)? Thanks, Luke I never realised my post would create such a debate. I think I'll go with the 09-09 period so my observations can be directly compared to other "official" stations. Thanks all. |
#17
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On Sun, 13 Nov 2016 02:06:57 -0800 (PST)
wrote: I never realised my post would create such a debate. I can't think why you didn't. This subject has been causing big debates here for the past couple of decades. ;-) -- Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer] Web-site: http://www.scarlet-jade.com/ There are more fools than knaves in the world, else the knaves would not have enough to live upon. [Samuel Butler] |
#18
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On 13/11/2016 09:27, Norman Lynagh wrote:
Ian wrote: I've always thought it a bit daft when recording 09-09 that particularly In winter your 09 obs of for example -2C is quite often your min for the next 09-09 period if there is a change to a milder airmass. 2 air frost days for the price of 1. Ian Raunds E Northants The same sort of thing happens no matter what recording period you use. For example, if there is a very short period of air frost from 2330 till 0030 that would only count as 1 air frost day if using the 09-09 recording period but it would count as 2 air frost days if you use the 00-24 recording period. Indeed a single night of air frost lasting, say, from 2000 till 0800 would count as 1 air frost day in the 0900-0900 recording system but would count as 2 days in the 0000-2400 system, even though there was actually only one night of air frost. No system is perfect. The important thing is to have a system and stick to it so that there is internal consistency withing your own set of observations. Strictly speaking, comparison with surrounding "official" stations is valid only if you use the 0900-0900 GMT recording period. On the Winter 1947 website I wrote 'Finally, from other sources, the minimum overnight temperature at Writtle (Essex) on the 28th/29th January was a rather chilly -5.1°F (-20.6°C) recorded at 0900 on the 29th. That 0900 reading has been assigned to 28th and/or 29th depending where you look. -- George in Swanston, Edinburgh, 580'asl www.swanstonweather.co.uk www.eppingweather.co.uk www.winter1947.co.uk |
#20
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On Friday, 11 November 2016 17:26:40 UTC, wrote:
Having just read the piece on observation timing on the FAQ pages, I wanted to see what the majority do with regards timings. 10 or so years ago, as a teenager with admittedly not much of an eye for detail, I used to take my readings at 1800 local time each day, noting the max/mins for the previous 24 hours. However, having had a little look on various sites I see 0900 local seems to be a more common time, along with splitting the climatological day into two periods. Or is a "normal" day seen as acceptable (00-24 local)? Thanks, Luke Having just visited the Met Office website, I notice on the "extremes" page for the last 24 hours, they have high/low max temp as having occurred between 09-21 on the date listed, and low min between 21-09 (along with rainfall and sun between 21-21). Do anyone of you follow this way of recording your extremes or should I follow the COL standards on this page http://www.met.reading.ac.uk/~brugge..._protocols.pdf |
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