Shade/direct sunlight issues with all in one weather stations

[richie3846]

I'm considering investing in an all in one weather station, but have one burning question that I've not yet found an answer for. 

These all in one stations appear to be commonly fixed to some sort of pole, recording rain, temperature, wind and humidity all from the one unit. The implication is that the unit may be in direct sun. Do the units protect the temperature gauge from direct sunlight by design, or do they give false readings? 

[Mapantz]

Radiation shielding needs to be in direct sunlight, and not in the shade.

If accuracy is important to you, you'll have trade-off's with all-in-one stations. If you value wind speeds, it'll need to be mounted high and that means you'll lose accuracy with rain and temperature.

If rain and temperatures are more important, you'll need to mount it lower and sacrifice wind readings.

Most all-in-one stations do have some kind of radiation shielding to help increase accuracy. They're not perfect, but they're ok for an enthusiast.

[richie3846]

1 minute ago, Mapantz said:

Radiation shielding needs to be in direct sunlight, and not in the shade.

If accuracy is important to you, you'll have trade-off's with all-in-one stations. If you value wind speeds, it'll need to be mounted high and that means you'll lose accuracy with rain and temperature.

If rain and temperatures are more important, you'll need to mount it lower and sacrifice wind readings.

Most all-in-one stations do have some kind of radiation shielding to help increase accuracy. They're not perfect, but they're ok for an enthusiast.

Yes wind readings are not are priority in my location. There is a steep hill to the north east that shelters much of the wind. Temperature and rain I hope to measure with some reasonable accuracy. I was considering placing it more or less in the centre of the garden over grass, a few feet high, which is about 25 feet away from the nearest building. Not ideal but is the furthest I have away from buildings and fences. 

[The PIT]

The only thought i have radiation shields is that they need a fan to keep a good air flow. I had a shield which didn't have a fan and it always read to high. I had a Davis 24hr well still got but I moved the sensor into the Stevenson shelter as I got fed up with replacing fans and recharging the batteries. Without the fan it would read to high with the fan it would closely match the max thermometer. Night time without the fan too high if it was a still night. 

The other advantage of having a fan is the increase in response time.

[Penrith Snow]

I find most weather station thermometers read too high in very sunny conditions as they don't have Stephenson screen type sunlight protection ie: double vents.

It's not ideal but I find putting the thermometer in the shade near (but not on) a North facing fence or wall gives better readings particularly in summer. In winter however this can give a lower max on a sunny day but its a reasonable trade off.

Andy

[reef]

On 15/06/2023 at 18:49, The PIT said:

The only thought i have radiation shields is that they need a fan to keep a good air flow. I had a shield which didn't have a fan and it always read to high. I had a Davis 24hr well still got but I moved the sensor into the Stevenson shelter as I got fed up with replacing fans and recharging the batteries. Without the fan it would read to high with the fan it would closely match the max thermometer. Night time without the fan too high if it was a still night. 

The other advantage of having a fan is the increase in response time.

Mine has been powered from the mains running a custom fan 24/7 for over 10 years now as I got sick of the poor quality (and expensive!) fans. With a decent high flow fan the accuracy and response is excellent.

I also ran a backup temp/humidity sensor in a Davis 7714 passive radiation screen and that generally tracked within 0.5C of the 24/7 FARS on maxima even at this time of the year. If you can find a sensor that fits it's a good choice. I ran a cheap Oregon sensor in it for years and it tracked the Davis very well until it failed.