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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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Just trying to gauge other peoples managemnt of the wet bulb readings
and I guess that I'm basically looking for best practice, tips, work rounds and how you rationalise them: also one quick question re dry bulb/max' temp readings. 1.) this is for those occassions when the Max' temp' is going to be at or about morning Obs - the Max' reads 9.9c, but the dry bulb reads 10.0c - what do you record as the max' temp'? 2.) WET BULB READINGS - when the wick/reservoir are frozen How do you work it - do you keep iced water handy to coat, spray the wick do you just use rain water, other, that isn't necessarily iced? do you always give it 15 mins to let the temp' fall do you just record it as it is (not the proper way) How do you annotate your daily record any other tips, considerations |
#2
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On Nov 18, 2:03*pm, wrote:
Just trying to gauge other peoples managemnt of the wet bulb readings and I guess that I'm basically looking for best practice, tips, work rounds and how you rationalise them: also one quick question re dry bulb/max' temp readings. 1.) this is for those occassions when the Max' temp' is going to be at or about morning Obs - *the Max' reads 9.9c, but the dry bulb reads 10.0c - what do you record as the max' temp'? 2.) WET BULB READINGS - when the wick/reservoir are frozen How do you work it - do you keep iced water handy to coat, spray the wick do you just use rain water, other, that isn't necessarily iced? do you always give it 15 mins to let the temp' fall do you just record it as it is (not the proper way) How do you annotate your daily record any other tips, considerations If the DB is higher than the max then one or both of them is/are wrong. The only answer is to stick to the max thermometer for maxes unless you can prove it has an error. This will ensure consistency among maxes even if slightly in error. But screens are rather arbitrary things anyway and have errors due to variable sunshine and ventilation. If the WB is frozen the approved method used to be, and may still be now, to remove the wick and paint the bulb with water just above freezing to form a thin layer of ice on it. This sounds rather tedious and what I would do, if I made this type of reading, would be to spray the bulb (with the wick still in place) with water and wait for it to freeze, ensuring that there is ice actually in contact with the whole of the bulb. Tudor Hughes, Warlingham, Surrey. |
#3
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Tudor - many thanks for the reply.
I like the 'Spray on' tip for the WB - might give that a go Re the DB and Max' readings - going with the Max' reading seems to be the consensus - not quite certain why I have had that 0.1c difference between the two. |
#4
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On Nov 18, 2:03*pm, wrote:
Just trying to gauge other peoples managemnt of the wet bulb readings and I guess that I'm basically looking for best practice, tips, work rounds and how you rationalise them: also one quick question re dry bulb/max' temp readings. 1.) this is for those occassions when the Max' temp' is going to be at or about morning Obs - *the Max' reads 9.9c, but the dry bulb reads 10.0c - what do you record as the max' temp'? 2.) WET BULB READINGS - when the wick/reservoir are frozen How do you work it - do you keep iced water handy to coat, spray the wick do you just use rain water, other, that isn't necessarily iced? do you always give it 15 mins to let the temp' fall do you just record it as it is (not the proper way) How do you annotate your daily record any other tips, considerations sovesse |
#5
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On Nov 18, 3:01*pm, Tudor Hughes wrote:
On Nov 18, 2:03*pm, wrote: Just trying to gauge other peoples managemnt of the wet bulb readings and I guess that I'm basically looking for best practice, tips, work rounds and how you rationalise them: also one quick question re dry bulb/max' temp readings. 1.) this is for those occassions when the Max' temp' is going to be at or about morning Obs - *the Max' reads 9.9c, but the dry bulb reads 10.0c - what do you record as the max' temp'? 2.) WET BULB READINGS - when the wick/reservoir are frozen How do you work it - do you keep iced water handy to coat, spray the wick do you just use rain water, other, that isn't necessarily iced? do you always give it 15 mins to let the temp' fall do you just record it as it is (not the proper way) How do you annotate your daily record any other tips, considerations * *If the DB is higher than the max then one or both of them is/are wrong. *The only answer is to stick to the max thermometer for maxes unless you can prove it has an error. *This will ensure consistency among maxes even if slightly in error. *But screens are rather arbitrary things anyway and have errors due to variable sunshine and ventilation. * * *If the WB is frozen the approved method used to be, and may still be now, to remove the wick and paint the bulb with water just above freezing to form a thin layer of ice on it. *This sounds rather tedious and what I would do, if I made this type of reading, would be to spray the bulb (with the wick still in place) with water and wait for it to freeze, ensuring that there is ice actually in contact with the whole of the bulb. Tudor Hughes, Warlingham, Surrey. If you're recording the DB and the Max remember to adjust the DB to agree with the Max (or vice verca). I've never heard of removing a wick from a wet bulb. The proper method is to paint the wick with distilled water, about 15-20 minutes before the reading time and an ice bulb should have formed by observation time. If you have a wet bulb with a temp below zero, you can induce freezing by touching the wick with a small scraping of hoar frost. |
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