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Earth's Hottest June on Record
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woodburner



Joined: 06 Apr 2009
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PostPosted: Tue Jul 30, 2019 8:58 pm    Post subject: Reply with quote

PS_RalphW wrote:
woodburner wrote:


Where is the Cambridge thermometer sited? It’s all very well quoting these so called “record” temperatures, but my thermometer, which is only 20 miles from Cambridge, registered a maximum of 32ºC since I last reset it months ago. It is sited in a position that has permanent shade, plenty of airflow, so it is measuring air temperatures, and does not have a direct sun exposure element.


The university thermometer is at the West Cambridge research site, about a mile outside of the city.
https://www.cl.cam.ac.uk/research/dtg/weather/implementation.html

.


Oh dear, just above a sunlit roof. Now, wouldn’t the air temperature be affected by being in such a position?
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kenneal - lagger
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PostPosted: Wed Jul 31, 2019 8:21 pm    Post subject: Reply with quote

Perhaps you should read the information fully, woodburner, and you wouldn't get the wrong information so often!

Quote:
The temperature sensor is located out of sight, below the overhang of the roof, and beneath the metal walkway. This position is out of direct sunlight.

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kenneal - lagger
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PostPosted: Wed Jul 31, 2019 8:27 pm    Post subject: Reply with quote

ReserveGrowthRulz wrote:
kenneal - lagger wrote:
No, RGR, it will heat the air to an extent but not to the extent that you don't feel the radiant heat.


So when you say a properly screened thermometer, you are referring to a screen that will not allow the infrared emissions to effect the thermometer?


The screen is designed to eliminate the effects of direct radiation so that the true air temperature is measured. IR will always effect the temperature measured because the IR heats the air.
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ReserveGrowthRulz



Joined: 19 May 2019
Posts: 507
Location: Colorado

PostPosted: Wed Jul 31, 2019 8:37 pm    Post subject: Reply with quote

kenneal - lagger wrote:
ReserveGrowthRulz wrote:
kenneal - lagger wrote:
No, RGR, it will heat the air to an extent but not to the extent that you don't feel the radiant heat.


So when you say a properly screened thermometer, you are referring to a screen that will not allow the infrared emissions to effect the thermometer?


The screen is designed to eliminate the effects of direct radiation so that the true air temperature is measured. IR will always effect the temperature measured because the IR heats the air.


Interesting. Also, recommended to be more than 100' from paved or concrete surfaces and whatnot
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adam2
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PostPosted: Wed Jul 31, 2019 8:44 pm    Post subject: Reply with quote

A reasonably accurate indication of air temperature may be obtained by an accurate thermometer placed in the shade and away from structures that may influence the reading.

For an official temperature reading as recognised by the met office, the thermometer needs to be placed within a white painted Stevenson screen which is a louvered wooden box placed at about 4 or 5 feet above ground level.
The louvers permit of plentiful air flow whilst preventing any direct access by radiant heat.
It is usual when great accuracy is desired to use several thermometers of different types.
The Stevenson screen also often contains a recording barometer, and a recording humidity instrument.

Adjacent to but outside the screen will usually be found a rain gauge, an anemometer, a wind direction recorder, a sunlight recorder and sometimes other instruments.
If it is desired to collect data on pollution this is often done at the same site.
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woodburner



Joined: 06 Apr 2009
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PostPosted: Thu Aug 01, 2019 12:21 am    Post subject: Reply with quote

kenneal - lagger wrote:
Perhaps you should read the information fully, woodburner, and you wouldn't get the wrong information so often!

Quote:
The temperature sensor is located out of sight, below the overhang of the roof, and beneath the metal walkway. This position is out of direct sunlight.


Look at the picture. You can see the walkway with the poles sticking up, you can see at the far end of the walkway the roof overhang. You can see just beyond that the sunlit roof. The sensor may be out of direct sunlight, but there is a lot of collected heat on that roof, it will be moved around by air currents, and it will be radiating. Of course that wouldn’t affect the sensor. Or would it?
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ReserveGrowthRulz



Joined: 19 May 2019
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PostPosted: Thu Aug 01, 2019 2:42 am    Post subject: Reply with quote

adam2 wrote:
A reasonably accurate indication of air temperature may be obtained by an accurate thermometer placed in the shade and away from structures that may influence the reading.


And apparently paving and concrete as well.
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woodburner



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PostPosted: Thu Aug 01, 2019 2:31 pm    Post subject: Reply with quote

I think paving and concrete can reasonably defined as “structures”.
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PS_RalphW



Joined: 24 Nov 2005
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PostPosted: Thu Aug 01, 2019 2:42 pm    Post subject: Reply with quote

woodburner wrote:


Look at the picture. You can see the walkway with the poles sticking up, you can see at the far end of the walkway the roof overhang. You can see just beyond that the sunlit roof. The sensor may be out of direct sunlight, but there is a lot of collected heat on that roof, it will be moved around by air currents, and it will be radiating. Of course that wouldn’t affect the sensor. Or would it?


The photo is of the Cambridge University weather station. It is not one of the met office stations that recorded the record temperatures. It peaked at 36.1C, not 37.8C

It clearly does not meet the scientific requirement for standardised data logging, and so is not included in the met office official records.
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ReserveGrowthRulz



Joined: 19 May 2019
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PostPosted: Thu Aug 01, 2019 3:43 pm    Post subject: Reply with quote

woodburner wrote:
I think paving and concrete can reasonably defined as “structures”.


SOME concrete anyway. I know of very few paved structures. Although, if you consider asphalt flung down on some dirt is a "structure", you would be right. I don't naturally think of a road or parking lot as a structure though.
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