Modifying dew point

[StratoQ]

Is there a way for meteohub to modify the dew point temperature?

In the settings area both temperature and humidity can be given assigned a new correction factor. Can the same be down for dew point?

[wfpost]

but most likely your humidity sensor is showing lower values than the correct ones, because it is placed in a protected location,
resulting in a lower dew point as well.
Temp shouldn´t be an issue.
So, if you correct Hum, dew point will be adjusted automatically as it is derived from Temp and Hum.

[StratoQ]

but most likely your humidity sensor is showing lower values than the correct ones, because it is placed in a protected location,

It is nothing to do with its location. It is an oregon combined temp/humidity sensor. The air temp values are fine but this type of sensor is not noted for great accuracy when it comes to humidity. So I always had to apply a correction factor for humidity.

So, if you correct Hum, dew point will be adjusted automatically as it is derived from Temp and Hum.

I have already used a correction factor to adjust the humidity reading - however meteohub does not adjust the dew point value accordingly. The dew point reported is still the original (uncorrected) value.

[StratoQ]

So to give an example, yesterday at 17:20 :

Oregon base station gave a reading of: Air Temp = 12.3 C and humidity = 29% and gives dew point of -5.1 C

I have a correction factor set up for both the air temp (-0.1C) and also to adjust the low humidity.

This then gives me more correct values on my meteohub/website of : Air Temp = 12.2 C and humidty = 48%. However the dew point is not adjusted accordingly and is still giving/graphing a reading of -5.1 C when it should be at +1.6 C.

Is there anyway to adjust the low dew point in line with the humidity correction factor? On my meteohub it doesnt do it automatically.

[wfpost]

then it´s a case for boris, because it seems like dew point is calculated with the raw values coming straight from the weatherstation ...

in the meantime you could use jscript on your website to calculate your dew point with printing in the corrected values for temp and hum as var and use them with jscript ...

http://en.wikipedia.org/wiki/Dew_point

[StratoQ]

I have sorted out my low dew point problem by setting up a virtual sensor.

To recap, I had set up a correction factor for my outdoor sensor humidity reading of 0.742 (a) and an offset (b) of +25.3. I am pretty happy with this correction - however I found the dew point is not adjusted in line.

So I set up a new virtual sensor. This takes the raw values coming from my outdoor sensor. I then had to make the same adjustments I had already made in the settings page( ie same correction factor for parameter $3 (outdoor temp) $4 (humidity) and include a new calculation for $5 (the dew point).

My dew point calculation is one of the more cruder methods of dp calc. But it is good enough for me. The final maths calculation for parameter $5 ended up somewhat complicated (involving 5 nested brackets) - but it worked!

Here is my gawk code:

awk '{ printf ''%s %s %s'', ($3-3), (($4*0.742)--25.3), (($3-3)-((100-(($4*0.742)--25.3))*2))}'

[Wessel]

Hi,

I have the same problem. I already adjusted the humidity, however the dew point is wrong yet. For example:

Temperature: 20.6ºC
Humidity: 92%
Dew point: 13.8ºC

The wrong dew point appears on WDL and Weather Underground. How could I solve it? I tried to create a virtual sensor, but it didn't work. Can somebody help me?