Author Topic: High Dewpoint due to high relative humidity reading Calibration?? WS2000  (Read 437 times)

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Offline jay2001

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I have a Ambient Weather WS-2000 Wi-Fi OSPREY Solar Powered Wireless Weather station. The temperature always checks out as good in relation to nearby airports and stations, the humidity however seems to run 4% higher pretty consistently and the dew point is affected by being 1.5 degrees higher also compared to nearby stations.

My question is do I simply go to the Humidity calibration and lower it by 4% which would correct both the humidity and the dewpoint to more closely match nearby airport and PWS readings? And by doing so will the station never read above 95% as the range is 1-99% and i corrected it by -4% (99-4=95)

Just want the data to be as accurate as possible as I am feeding data into MADIS.
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« Last Edit: January 26, 2023, 09:52:23 AM by jay2001 »

Offline Rover1822

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #1 on: January 26, 2023, 12:42:04 PM »
Do you have another unit to compare to, at your precise location? Humidity levels vary wildly, worse than temperature.


Edit: Kudos if every other measurement you have matches, but then , that would also be unusual. For me, the point is not to match others at off locations , it is , to get my measurement as accurate as possible at my location, on whatever I am concerned about. I mean within reason, I mean if you are way off , beyond known device error , etc. 4% on humidity , is actually quite small.
« Last Edit: January 26, 2023, 12:54:34 PM by Rover1822 »
Ambient:
  WS-2000
  PM 2.5(2)
  WH31B(2)
  WH40E
  WH31P
EcoWitt:
  GW1100
  GW1000(4)
  WH31(2)
  WH57
  WH51(12),
  WH40
  WH5360B
  WN34S
  WittBoy WS90 + GW2000
  WS90 (other one) + GW1100
Personal Sites: Weather Cam

Offline jay2001

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #2 on: January 26, 2023, 01:38:42 PM »
No, I dont have another unit here at my exact location to compare.  :-( but what relitive humidity should i be seeing if its raining at the time? I always see 99% solid when it rains.

Offline Gyvate

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #3 on: January 26, 2023, 02:46:51 PM »
No, I dont have another unit here at my exact location to compare.  :-( but what relitive humidity should i be seeing if its raining at the time? I always see 99% solid when it rains.
99% (=condensed water = rain) makes a lot of sense during rainfall
WS2350 1.6.5, GW1000(3) 1.7.6, WH2650 WiFi (2) 1.7.6 (test/backup), GW1100 2.2.3, GW2000(3) 2.2.3, HP2551 1.9.0, WN910 1.2.2;
Ecowitt WS90(2), WS80, WH40, WH65, WH31(5), WH31-EP, WN30, WN34L, WN35, WH32, WH32-EP, WH32B, WH57 [Lightning], WH41 [PM2.5] (2), WH51 (4), WH45, WH55
MeteobridgePro(2)[test,prod] 5.5 Oct 27 2022, 14855 - Blake-Larsen Sun Recorder - RPi4/weewx 4.8.0/CumulusMX 3244/Meteobridge RPi4B-2GB(2977)
Barani Meteoshield Pro, MetSpec Rad02 - Ecowitt 5763,34418;WU ISAARB3(WH4000SE), ISAARB22(HP2553), http://meshka.eu

Offline Rover1822

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #4 on: January 26, 2023, 02:47:58 PM »
What Gyvate said... I agree
Ambient:
  WS-2000
  PM 2.5(2)
  WH31B(2)
  WH40E
  WH31P
EcoWitt:
  GW1100
  GW1000(4)
  WH31(2)
  WH57
  WH51(12),
  WH40
  WH5360B
  WN34S
  WittBoy WS90 + GW2000
  WS90 (other one) + GW1100
Personal Sites: Weather Cam

Offline jay2001

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #5 on: January 26, 2023, 02:58:54 PM »
No, I dont have another unit here at my exact location to compare.  :-( but what relitive humidity should i be seeing if its raining at the time? I always see 99% solid when it rains.
99% (=condensed water = rain) makes a lot of sense during rainfall
I know it sounded like a silly question, but I just thought it should vary some between maybe 90-99 during rain but its always pegged at 99 during light rain even now its snowing lightly. That's another reason i was kinda wondering if the humidity needed calibrated a little.

Irregardless what would be the best way to make sure that the humidity sensor is reading properly (accurately)
« Last Edit: January 26, 2023, 03:04:16 PM by jay2001 »

Offline CW2274

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #6 on: January 26, 2023, 04:12:51 PM »
No, I dont have another unit here at my exact location to compare.  :-( but what relitive humidity should i be seeing if its raining at the time? I always see 99% solid when it rains.
99% (=condensed water = rain) makes a lot of sense during rainfall
I know it sounded like a silly question, but I just thought it should vary some between maybe 90-99 during rain but its always pegged at 99 during light rain even now its snowing lightly. That's another reason i was kinda wondering if the humidity needed calibrated a little.
Rainfall alone does not 99% humidity make. As a generality, you need fog for that. Sounds like your sensor is a little off IMHO.

Offline Gyvate

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #7 on: January 26, 2023, 04:51:53 PM »
Rainfall alone does not 99% humidity make. As a generality, you need fog for that. Sounds like your sensor is a little off IMHO.
sure - only fog as the predecessor of bigger rain drops will create 99% - raindrops are much drier -
of course not the raindrops (they are 100%) but the whole air.
Humidity depends on the saturation of the air by water vapour and is temperature dependent.
However, inside these small radiation shields of the sensor arrays where the T/RH sensors are usually located (WS69/WH65/WS80/WS90), the airflow is quite restricted and an artificial foggy micro environment can be easily created during longer rainfalls.
If your T/RH sensor is inside a professional radiation shield - like with my Barani MeteoShield Pro - such a "fog congestion" doesn't occur due to the design.
My T/RH sensor inside my MeteoShield shows generally much lower RH values than the sensor arrays.
« Last Edit: January 26, 2023, 05:07:26 PM by Gyvate »
WS2350 1.6.5, GW1000(3) 1.7.6, WH2650 WiFi (2) 1.7.6 (test/backup), GW1100 2.2.3, GW2000(3) 2.2.3, HP2551 1.9.0, WN910 1.2.2;
Ecowitt WS90(2), WS80, WH40, WH65, WH31(5), WH31-EP, WN30, WN34L, WN35, WH32, WH32-EP, WH32B, WH57 [Lightning], WH41 [PM2.5] (2), WH51 (4), WH45, WH55
MeteobridgePro(2)[test,prod] 5.5 Oct 27 2022, 14855 - Blake-Larsen Sun Recorder - RPi4/weewx 4.8.0/CumulusMX 3244/Meteobridge RPi4B-2GB(2977)
Barani Meteoshield Pro, MetSpec Rad02 - Ecowitt 5763,34418;WU ISAARB3(WH4000SE), ISAARB22(HP2553), http://meshka.eu

Offline CW2274

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #8 on: January 26, 2023, 05:02:23 PM »
Rainfall alone does not 99% humidity make. As a generality, you need fog for that. Sounds like your sensor is a little off IMHO.
sure - only fog as the predecessor of bigger rain drops will create 99% - raindrops are much drier - I see ...
I've been looking at wx instruments data daily for 45 years, professionally, and as a hobbyist. I call it as I see it.

Offline Gyvate

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #9 on: January 26, 2023, 05:04:28 PM »
Rainfall alone does not 99% humidity make. As a generality, you need fog for that. Sounds like your sensor is a little off IMHO.
sure - only fog as the predecessor of bigger rain drops will create 99% - raindrops are much drier - I see ...
I've been looking at wx instruments data daily for 45 years, professionally, and as a hobbyist. I call it as I see it.
Maybe have a look at the edited post  ;) - it got saved before completion.  :roll:
I think we are on the same page.
« Last Edit: January 26, 2023, 05:06:11 PM by Gyvate »
WS2350 1.6.5, GW1000(3) 1.7.6, WH2650 WiFi (2) 1.7.6 (test/backup), GW1100 2.2.3, GW2000(3) 2.2.3, HP2551 1.9.0, WN910 1.2.2;
Ecowitt WS90(2), WS80, WH40, WH65, WH31(5), WH31-EP, WN30, WN34L, WN35, WH32, WH32-EP, WH32B, WH57 [Lightning], WH41 [PM2.5] (2), WH51 (4), WH45, WH55
MeteobridgePro(2)[test,prod] 5.5 Oct 27 2022, 14855 - Blake-Larsen Sun Recorder - RPi4/weewx 4.8.0/CumulusMX 3244/Meteobridge RPi4B-2GB(2977)
Barani Meteoshield Pro, MetSpec Rad02 - Ecowitt 5763,34418;WU ISAARB3(WH4000SE), ISAARB22(HP2553), http://meshka.eu

Offline weatherdoc

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Offline jay2001

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #11 on: January 28, 2023, 11:31:33 AM »
Thank you I ended up constructing my own sling psychrometer (cost seemed a little excessive for something I could get at my local hardware for a couple dollars per thermometer.) Once I learned how to use it and practiced I was getting consistent results within +/- 3 RH of my WS-2000 weather station. I used an online calculator to get the RH% from my sling psychrometer taking into account wet bulb, dry bulb and barometric pressure observations at the time of the reading. I also found out that being between +/- a couple percent RH is pretty good.
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Offline weatherdoc

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Re: High Dewpoint due to high relative humidity reading Calibration?? WS2000
« Reply #12 on: January 28, 2023, 01:34:18 PM »
Yes, much better than $62! I [barely] remember making a sling psychrometer in middle school (50-ish years ago!).

 

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