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.