Topic: High Humidity Readings In The Morning

[Jack Bowman]

   I seem to be getting high humidity readings early in the morning hours. As soon as the sun comes up, and the aspiration fan starts in the 5-in-1 sensor, it become accurate. I am comparing to nearby weather stations in my area. The sensor is 10 feet off the ground (short Grass) away from any structures, or trees. I have a large cottonwood tree, and house to the west of the sensor about 100 feet. I think this shade actually helps keep the temperature accurate at the end of the day when the aspiration fan stops. Anybody ever powered there fan 24/7? Is the 5-in-1 supposed to make a whirring noise when it is powered by the solar panel?

Jack

[DanS]

" as the sun comes up, and the aspiration fan starts in the 5-in-1 sensor, it become accurate "

I'm not sure I'd be worried about it because humidity (as well as many other) readings can vary greatly in short distances so maybe not good to use neighbors as a reference. If it is something you believe is wrong do you have another, trusted, hygrometer you can place nearby your station sensor to validate the readings? The early morning hours are when humidity can be it's highest before the sun rises and dries things out.

[Jack Bowman]

Thanks DanS! I do have another hygrometer that I can place near it. Great idea. I don't think there is anything wrong with the sensor as it is very accurate the rest of the time. The unit is maxing out at 99 for about an hour in the mornings. Just wondering why surrounding weather stations are able to maintain consistent readings. I would like to achieve this as well if possible. Thanks again for your feedback.

Jack

[Weather Display]

maybe hardwire the fan to an external power source

[Jack Bowman]

maybe hardwire the fan to an external power source

I was thinking about this. I just elevated the sensor another 4 feet off the ground just to see if it makes a difference. My grass is pretty wet, and the ground is still muddy from recent storms. I guess we will find out in the morning. Thanks for the feedback!

Jack

[Jack Bowman]

UPDATE: Raising the sensor farther off the ground seems to have kept the humidity from pegging at 99, and brought the readings down to within other local weather stations in my area. My 5-in-1 sensor is now at 12 feet. I used a 4 foot section of 3/4 inch PVC electrical conduit with an outside diameter of 1 inch to increase the height. I need to replace this with something more ridged to stabilize, and level the sensor.

[nincehelser]

The whirring noise is normal.  It's when you don't hear it and the sun is out that you might be concerned.

As for the humidity, I agree with DanS.  It can vary greatly depending on your surroundings.  Trying to make it match some else's reading might not be a a good idea.

I have had high humidity in the morning lately, but that's why there's fog.  It burns off quickly as the sun rises.

You might get another tower sensor (about $8) and mount somewhere else on your property and see if you notice a difference.

Historically, some 5-in-1s get "stuck" showing a high humidity.  This was/is due to a faulty sensor.  Hopefully all those have been replaced by now, but you still hear of one every once in a while.  If you get one that seems "stuck", call customer service and they often replace them regardless of warranty status.

[Jack Bowman]

I really appreciate all the insight, and knowledge you share nincehelser. Thanks!

Jack

[nincehelser]

As to the pole, you really do need to replace it with something more rigid as you say.

If the pole sways in high winds, the motion may cause the rain buckets to tip and register "false rain".

[Jack Bowman]

     I have this all taken care of now. A 1/2 inch conduit slides perfectly inside the 3/4 inch grey pvc conduit. This straightened it out completely, and made it very rigid. leveled of the the sensor nicely. Very solid mount now. The wind is blowing, and the rain is falling as I type this. No movement except for the wind instrumentation.    Here is a photo of the finished product...

[DaculaWeather]

Keep in mind that the humidity is going to rise as the temperature falls, all else being the same. Mine almost always gets up in the 90% range, the last two days it was 100%. Watch your dewpoint and humidity as the temperature begins to fall.

And yes, the closer to the ground, generally the more moist, especially in the early morning hours. This morning I had a low fog over my backyard... really nice to look at.

And remember, temp and humidity should be measured at 5 feet.

[Weather Display]

humidity is relative
its the dew point you should be using to compare

[Jack Bowman]

And remember, temp and humidity should be measured at 5 feet.

...and this is the downfall for all-in-one sensors. The anemometer needs to be higher, and the rain gauge, temperature/humidity at a lower height. This is my compromise height for my environment. My next weather station will be separate sensors for sure.

[nincehelser]

...and this is the downfall for all-in-one sensors. The anemometer needs to be higher, and the rain gauge, temperature/humidity at a lower height. This is my compromise height for my environment. My next weather station will be separate sensors for sure.

I keep wrestling with this issue, particularly with the wind.

Take wind chill, for example.  My understanding is that it should be calculated with wind speed at "face-level".   If your anemometer is at 30', can you really have a meaningful wind chill value?

For most of my daily activities, wind speed at face-level seems most meaningful.  However, I can see where 30' can be useful for things like aviation, kite flying, and regional weather prediction.

Maybe the best weather stations should have two anemometers... one at face level and one at 30' (or whatever height is considered "optimal")

[DanS]

" Maybe the best weather stations should have two anemometers... one at face level and one at 30' "

That's an interesting point! Like you say, a lower located anny used for the wind chill and "feels like" temp calculations and a normally located upper anny/vane used for the local area wind speed/direction.

[Spartan300]

Nicely mounted there Colorado! You have those sensors high and level.