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Author Topic: Should thermometers be shielded?  (Read 1541 times)

Offline Bob Lindo

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Should thermometers be shielded?
« on: 05/05/2010 12:30:02 »
Bob Lindo asked the Naked Scientists:
   
Dear Doctor Smith
 
I'm recording night time minimum temperatures using a data logger, and also a conventional max/min mercury thermometer.  

Is it necessary to encase these thermometers in the way they are usually done during the day, to isolate the direct sun?  

In other words, I know there's no sun, but is there an effect where the thermometer can cool below it's surroundings as it presumably radiates heat away too?
 
Many thanks
 
Bob Lindo


What do you think?
« Last Edit: 05/05/2010 12:30:02 by _system »


 

Offline lightarrow

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Should thermometers be shielded?
« Reply #1 on: 05/05/2010 13:37:49 »
No, you don't have that kind of effect in yhe night, brcause even if it's certainly true that it radiates heat away, it cannot go down the surrounding temperature.
 

Offline Bob Lindo

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Should thermometers be shielded?
« Reply #2 on: 07/05/2010 15:23:34 »
Thanks, but I didn't mean lower than a final stable temperature.  I was wondering if the rate of cooling, proportional to mass, Specific Heat and temperature change might vary with the set up of the data logger in relation to its surroundings and whether there was an accepted method of positioning.
 

Offline lightarrow

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Should thermometers be shielded?
« Reply #3 on: 08/05/2010 13:36:27 »
Thanks, but I didn't mean lower than a final stable temperature.  I was wondering if the rate of cooling, proportional to mass, Specific Heat and temperature change might vary with the set up of the data logger in relation to its surroundings
That's for sure, but it depends on which is the instrument's sensitivity and which is the requested precision of the measurement.

Quote
and whether there was an accepted method of positioning.
If you talk of an "accepted method of positioning" you have to refer to a specific kind of measure, then it's the firm who make the instrument who have to define the measuring procedure. If, furthermore, you are making a measurement which will have to have legal validity, then you also have to refer to the current laws and technical rules.
« Last Edit: 08/05/2010 13:38:45 by lightarrow »
 

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Should thermometers be shielded?
« Reply #3 on: 08/05/2010 13:36:27 »

 

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