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Weather Station Hardware => Davis Instruments Weather Stations => Topic started by: DRoberts on May 30, 2018, 08:01:28 PM

Title: Vantage Pro2 humidity reading high?
Post by: DRoberts on May 30, 2018, 08:01:28 PM: New set up. Is it possible that the AWOS 6 miles away at the airport can be 26% while my VP2 is showing 49% on the console? Location of my ISS is rural, grassland/prairie.

Thoughts?

(FYI, my tech vocab and level is beginner)
Title: Re: Vantage Pro2 humidity reading high?
Post by: Old Tele man on May 30, 2018, 08:18:15 PM: How "new" is that setup? I advise NOT making any changes for the first month...just collect and compare...because local "micro-climate" differences are real. Learn first what your local differences are before making changes.

Any other CWOP stations nearby (within 20-30 miles)? The closer they are the more likely they are to provide "guidance" (assuming they're semi-calibrated).

What does the MADIS (Gladstone) "Quality Checking" say about your data?
Title: Re: Vantage Pro2 humidity reading high?
Post by: CW2274 on May 30, 2018, 08:19:31 PM: Quote from: DRoberts on May 30, 2018, 08:01:28 PM
New set up. Is it possible that the AWOS 6 miles away at the airport can be 26% while my VP2 is showing 49% on the console? Location of my ISS is rural, grassland/prairie.

Thoughts?

(FYI, my tech vocab and level is beginner)
What AWOS please?
Title: Re: Vantage Pro2 humidity reading high?
Post by: Mattk on May 30, 2018, 08:22:34 PM: Quote from: DRoberts on May 30, 2018, 08:01:28 PM
New set up. Is it possible that the AWOS 6 miles away at the airport can be 26% while my VP2 is showing 49% on the console? Location of my ISS is rural, grassland/prairie.

Thoughts?

Yes
Title: Re: Vantage Pro2 humidity reading high?
Post by: DRoberts on May 30, 2018, 08:46:30 PM: Old Tele man, Very new. Third day of use. Might be a CWOP about 30 miles from me. Have to check. MADIS? I have heard the term, but know nothing about it.

CW2274, http://www.saiawos3.com/PHG/index2.html

Mattk, Thanks.

I will wait and compare data. Will look to see if I can access a CWOP site, but it is pretty far away I think.

Thanks for advice. Any other thoughts welcome.
Title: Re: Vantage Pro2 humidity reading high?
Post by: jas340 on May 30, 2018, 08:59:47 PM: Comparing humidity to another station is a "bad" idea. They don't call it "relative humidity" for nothing. Dew point is the number you want to compare. Dewpoint is the actual amount of moisture in the air. Use this calculator and enter in temp and dew point to your comparison station.

http://andrew.rsmas.miami.edu/bmcnoldy/Humidity.html (http://andrew.rsmas.miami.edu/bmcnoldy/Humidity.html)
Title: Re: Vantage Pro2 humidity reading high?
Post by: CW2274 on May 30, 2018, 09:07:32 PM: Obviously continue monitoring. Here's your AWOS's Mesowest page.
http://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=KPHG&unit=0&timetype=LOCAL

Here's another temp/dew/humidity calculator, little easier I think.
http://www.dpcalc.org/
Title: Re: Vantage Pro2 humidity reading high?
Post by: DRoberts on May 30, 2018, 09:13:44 PM: jas340, Figures are close using that link. RH is 3% higher when I enter the DP with current temp. DP is right on the dot when I enter the RH with current temp.

CW2274, Thanks for those links. I am a bit caught up in the acronyms right now. Have to try to figure what they all mean and how they relate to each other.

I am CoCoRaHS, but that may be the only one I really understand. :-)

Guess everybody can come close to finding where I live. :-)

Thanks, all
Title: Re: Vantage Pro2 humidity reading high?
Post by: ValentineWeather on May 30, 2018, 11:24:35 PM: Quote from: DRoberts on May 30, 2018, 09:13:44 PM

Guess everybody can come close to finding where I live. :-)

Not very hard, most here publicly post our locations If we have websites or give data to CWOP, Cocorahs etc. Ken has a map somewhere for putting your location. ;)