Maplin N96FY - (Watson 1081) - wind and rain

[Aberthin]

As someone new to all this I bought the Maplin N96FY and installed Cumulus.
I have noticed that the base station shows the minimum windspeed is never less than 1.1km/hr (apart from zero when there is no wind).
I also wonder if the higher speeds indicated are are low because they are so much lower than those at RAF St Athan some five miles away. Is this normal for this weather station?

I also notice that Cumulus tells me the minimum rainfail rate, when raining, is never less than about 3.5mm per hour. Again, this normal for this weather station?
However it will show minimum rainfall of 0.3mm, which I have interpreted from other posts, to be about right for this machine.

Any advice would be appreciated

[steve]

Cumulus calculates the rainfall rate from a simple formula based on the rain in the last 5 minutes (the station doesn't bother, I guess it was too hard for them) which is why it tends to be restricted to a small set of values, when you take into account the 0.3 mm per tip resolution. I'd like to improve the algorithm a bit, but my last attempt caused problems, so that's shelved for a while.

Rain rate is a funny beast with TBRs because you never know at any given moment if it's actually raining, or how hard.

Steve

[Aberthin]

Thank you, Steve. Your reply is helpful.

[harrym1byt]

As someone new to all this I bought the Maplin N96FY and installed Cumulus.
I have noticed that the base station shows the minimum windspeed is never less than 1.1km/hr (apart from zero when there is no wind).
I also wonder if the higher speeds indicated are are low because they are so much lower than those at RAF St Athan some five miles away. Is this normal for this weather station?

The location of the anemometer can make huge differences to the higher speeds. Only if you can get this sensor up high and well clear of buildings and trees can you get reliable speeds recorded and accurate directions Mine reads low at the higher speeds, but I would expect it because its mounting location was very much a compromise.

[dc1500]

As Harry says, and with temperature, siting can make a vast difference. If you can't get a high clear location the best thing might be to monitor it for a while against the local RAF station and then apply a calibration factor (Cumulus drop down menu). Often, we just have to accept the error and use it as a relative measurement for our own little environment.
Dave

[Aberthin]

Thank you, both. I guess I will never get accurate readings here because of the proximity of trees and houses. I really wondered if anyone else noticed a minimum speed of 1.1km per hour (apart from zero) from their machine.

[harrym1byt]

Thank you, both. I guess I will never get accurate readings here because of the proximity of trees and houses. I really wondered if anyone else noticed a minimum speed of 1.1km per hour (apart from zero) from their machine.

Difficult to be sure, but I'm seeing a sometimes flat line at around 2/3rds of 1mph if I really zoom into the wind speed graph - which roughly coincides with your 1.1kph. There are bound to be discrete steps, after all it is digital.

[steve]

The station measures in m/s, and 1.1 kph is 0.3 m/s, so perhaps that is the lowest value it does.

Steve