Humidity tuning

Must be a very slow learner. Mine has been out there for several days and has remained stuck at 99% humidity the whole time, running some 30% higher than neighboring stations.

Hi @unkajim. Welcome to the family. As of 8 Jan, our CL system has only collected three days of data since you set up your new station. We are tracking 5 different data sources in your immediate area. Once the data set corroborates and produces a valid baseline humidity reference value…the calibration will be automatically applied to your station. - the WF team

Thanks. Good to know. Wonder if one of the tracked sources is my 1-Wire humidity sensor, located two feet to the south of the Air.

Just measured via my Assman psychrometer (the good old one), I get a reading of 78° when my Airs show 81°. Think it is pretty ok, as the Airs are in a stevenson screen and I measure just outside them. Added the standard deviations of the Airs and my eyes :wink:

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Mine’s still stuck on 99%. If I could get at it via some interface, I would give it a negative 25 offset which would get it in the ballpark.

Hello @unkajim . Appreciate the heads up. Took a peek at the CL comparison data for humidity for your station and the reference values have not been in agreement. Will have our humans take a look.

FYI – calibration is not as simple as a fixed value or % offset. Rather, we look at the spectrum of comparison humidity values to determine linear slope and offset. For example, your sensor might need to be tuned down xx% at the top end of the humidity spectrum, might be perfect in the mid-range, but under-reporting yy% in the lowest range. (This is very common with humidity sensors.)


@WFstaff-One ongoing issue I’ve had is with my Air’s humidity readings lagging actual changes. Today we had a rain storm and although humidity in my area was 98% or a bit higher at most reporting stations, including my own Davis VP2, my Air reported a peak of only 94%. However the more significant issue is that now that the storm has passed, humidity has dropped to the 74-79% in my area (79% on my VP2) and my Air is still stuck at 91%, falling only 3% since 12pm. I’m not sure why this long lag exists or if this is something the CL system can or will detect and adjust.

Describe the area around the Air. Posting a photo would be even better.

How high above ground is the Air sitting? How close is the nearest plant life. Does the Air have good ventilation?

Gary, my VP2 is actually fairly close to a bush (too dark to take a pix now, but I’ll get one tomorrow) and my Air is sitting on a table for now, quite a bit further from any plant life. Both the Air & VP2 are about at the same height, 12’ or so above ground level. The Air has excellent ventilation in all directions.

Here are 2 pix of the humidity/DP plots. The VP2 plot is from WU and doesn’t give humidity directly, but does give temp & DP. My Air is still sitting at 91%, unchanged.

IMG_1273 IMG_1274

Ah. What is the table top made of and is the table top wet?

Gary, that might be a good call. Table is metal. I just went out to take a pix with the iPhone flash. There is definitely dampness on the table, but the Air is raised a bit off the table. Do you think that’s enough moisture to impact the slow drying? I’ve also included a shot of my VP2. IMG_1270 IMG_1275

From my experience it does not take much moisture to raise the humidity. Move it to a dry area and see it if changes.

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Gary, if you look closely you can see that there is still quite a bit of moisture on the Air itself. So I wonder if even if the table were totally dry, how much would the Air be impacted by the moisture on the unit itself?

Move the Air but don’t dry it off. See if it changes.

I’ll give it a shot. I actually dried off the table after having shot this picture. :slight_smile:

OK, moved it to a dry ladder I just put out on the deck. Thanks for the idea, we’ll see what impact this has. But I still wonder about all the moisture still on the Air’s casing.

Once in a dryer area the rain on the Air will evaporate quicker and the humidity should drop.

Gary, thanks, I’ll let you know in the morning how this progressed. I’ve ordered a passive radiation shelter for the Air as I’ll probably have an issue for total shade as the seasons change. Do you know what impact a shelter has on the Air’s ability for lightning detection?

I don’t personally know but others have had little to no issues.

none as long it isn’t full metal and grounded.
Mine are in a wooden Stevenson shelter and detect normal