Author Topic: Temperature in shade vs temperature in enclosure with aspirator  (Read 767 times)

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Offline rainman1962

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Let's start with an assumption...I was always taught that temperature readings should be made in the shade.  I currently have a 5-1 Acurite Pro (2 solar panels).  Temperature is measured in full sun but there is an aspirating fan build in.

Question:  Is temperature measured in shade RIGHT NEXT TO temperature measured in full sun with an aspirator supposed to be equal? 

  • The height is the same for both conditions (about 6 feet); 
  • there is greenery below and grass on all sides;
  • the aspirating fan is brand new and working fine.
  • 30 feet from any structures
  • the thermometer in the shade is analog, alcohol filled +/-1 degree model.  I have verified that it is spot on at 32 degrees by filling a glass full of ice and water and mixing it for about 5 minutes.

The 5-1 with aspirator consistently measures 4-5 degrees warmer at the peak of the day and at night (or cloudy days) both thermometers read about the same.

I have reviewed many of these problems on this forum and the Acurite forum with sometimes quite heated back and forth.   It seems to me that I have isolated all the variables (accuracy of reference thermometer, horizontal/vertical position, proximity, fan operation).  Hopefully the NWS isn't using these devices...4-5 degrees warmer might explain anthropomorphic warming  ;)!

Am I missing something or are these weather stations not accurate in full sun?


Offline CW2274

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #1 on: August 06, 2017, 03:45:58 PM »
If your station is to be in the sun, a quality radiation shield is a must, and preferably aspirated. How many airports have their wx stations in the shade? If I were a betting man, I'd say none. ;)
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Offline rainman1962

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #2 on: August 06, 2017, 08:10:28 PM »
If your station is to be in the sun, a quality radiation shield is a must, and preferably aspirated. How many airports have their wx stations in the shade? If I were a betting man, I'd say none. ;)


Put more concisely...Does a reading in the shade=a "quality radiation shield, preferably aspirated"? Or, at least, should it?
« Last Edit: August 06, 2017, 08:13:34 PM by rainman1962 »

Offline CW2274

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #3 on: August 06, 2017, 08:23:36 PM »
If your station is to be in the sun, a quality radiation shield is a must, and preferably aspirated. How many airports have their wx stations in the shade? If I were a betting man, I'd say none. ;)


Put more concisely...Does a reading in the shade=a "quality radiation shield, preferably aspirated"?
To the "nth" degree, no. Even the best shields money can buy cannot completely eradicate solar insolation, fan or not. That being said, they can be very good, only adding a few tenths of C at worst. Not having your PWS exposed to the elements properly kinda defeats the purpose of owning it in the first place, at least for my me.
Davis Wireless VP2 SHT31 24hr 67CFM FARS
RW Tipper w/ CoCoRaHS

Offline benay ra'am

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #4 on: August 06, 2017, 09:41:17 PM »
Let's start with an assumption...I was always taught that temperature readings should be made in the shade.  I currently have a 5-1 Acurite Pro (2 solar panels).  Temperature is measured in full sun but there is an aspirating fan build in.

Question:  Is temperature measured in shade RIGHT NEXT TO temperature measured in full sun with an aspirator supposed to be equal? 

  • The height is the same for both conditions (about 6 feet); 
  • there is greenery below and grass on all sides;
  • the aspirating fan is brand new and working fine.
  • 30 feet from any structures
  • the thermometer in the shade is analog, alcohol filled +/-1 degree model.  I have verified that it is spot on at 32 degrees by filling a glass full of ice and water and mixing it for about 5 minutes.

The 5-1 with aspirator consistently measures 4-5 degrees warmer at the peak of the day and at night (or cloudy days) both thermometers read about the same.

I have reviewed many of these problems on this forum and the Acurite forum with sometimes quite heated back and forth.   It seems to me that I have isolated all the variables (accuracy of reference thermometer, horizontal/vertical position, proximity, fan operation).  Hopefully the NWS isn't using these devices...4-5 degrees warmer might explain anthropomorphic warming  ;)!

Am I missing something or are these weather stations not accurate in full sun?

Most of the Acurite Station on WU in my local area read High anywhere from 3-10 degrees. My 5-in-1 reads 3 High, sometimes 4 in full sun in the afternoon. I just bought a Davis 6153 ( 24 Hour Fan ). Does this mean I'm dumping on Acurite? Nope, it's going to stay up along with the Davis once I get it installed. I have modding plans for the Acurite.




CoCoRaHS: NC-JH-80

Offline Bashy

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #5 on: August 07, 2017, 12:22:08 AM »
The shade will read cooler than even a Met O approved SS and to me, it would not be an official reading due to all the official
stations being in direct sunlight. However, that is not to say that the shade is inaccurate, its not, its prob more accurate than
in sunlight due to no warming of  the ground, having said that, you being at 6ft negates any and all readings as you are too high.

You see, you are trying to be perfect in a non perfect setting, not often is it achieved in back yard stations, my answer to you is,
If you are happy with the readings in the shade, then  place it there, i have done in the past when being in the sun was not working.
If it works for you, do it, cant be any worse than a Netamo station ;)
Kind regards
Bashy

Offline skysummit

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #6 on: August 13, 2017, 11:50:06 PM »
I've been having some great results from my radiation shield in comparison to my 5 in 1.  However, I will be modifying my shield soon with a solar panel on top and fan below it to pull air in.
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Offline WxLover16

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #7 on: August 15, 2017, 04:47:50 PM »
I've been having some great results from my radiation shield in comparison to my 5 in 1.  However, I will be modifying my shield soon with a solar panel on top and fan below it to pull air in.

Nothing beats a fan for more accurate data, that's for sure.
Davis Wireless VP2 SHT31 24hr 24CFM FARS

Offline Garagedude

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #8 on: September 03, 2017, 12:34:51 PM »
I built a 6in thick insulated box with fan for my Acurite Pro+. It keeps same temps as Davis. If I remove shield the temp soars.

Offline jonkjon

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #9 on: September 07, 2017, 01:09:08 PM »
I built a 6in thick insulated box with fan for my Acurite Pro+. It keeps same temps as Davis. If I remove shield the temp soars.

Have any pics of it? That would be interesting to see....

--Jon

Offline NinnJinn

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #10 on: September 19, 2017, 08:44:15 PM »
I would be interested in seeing pics as well.

Offline Glenn

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Re: Temperature in shade vs temperature in enclosure with aspirator
« Reply #11 on: September 20, 2017, 09:20:35 AM »
I've found both of my 5 in 1 stations to be pretty spot on..even when in the sun. They tend to actually run a bit cooler than other local stations in my area.
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