Rain Duration Sensor

To start of I will explain how this has come about. Basically without the Rain Duration sensor the Weather software (Weather Display) I am using could not determine if it was raining until the rain bucket made a tip (when full) thus telling the software its raining, this could actually take anything up to and beyond a few hours for very fine drizzle.

Now, imagine the scenario, its just started drizzling (fine rain), because its not much at all the rain bucket has not tipped, therefore the weather software does not know its raining and also the website does not know its raining and the icon will be anything other than rain, perhaps sunny or overcast. This in turn could be very misleading, more so if someone wants to visit Desborough but only if its not raining, well imagine there surprise to find out it is when they get here, not good really.

So I asked the question about this on the Weather Watch forum and a chap called Mick from Weather Above mentioned that he could have a go at building a Rain Duration sensor. The sensor would know straight away if its raining or not, that sounded exactly what I wanted and he went ahead and built it.

Basically the rain sensor itself is attached to an Oregon Scientific extra temperature probe (THC238), this then connects to my console as an extra sensor. How it works is, when its dry the sensor will read 20.4 for no rain and 54.2 for  rain. Now, I have only just received the sensor and its still under testing, any figure in between going up should be rain just started and if its going back down again then this should indicate that the rain has stopped. If the graph has not gone above 38 then I would say its possibly Dew.

You can see from the image below, the 1st circle was when I 1st tested it with a fine mist from the hose. the 2nd circle was when it actually rained, you can see from the 1st 2 little steps lower down at that point it was actually spitting, then the rain started, the 3rd circle is when it started again but not for long and again a few more times, this is indicating a few showers. Now just before it really drops off, you can see 4 small spikes around 37, 36.5, 36 then one more at about 27, this was  Dew. Also from the graph you can see the pale blue line, this is the actually the rain amount in millimetres 0.5mm and then 0.3mm after midnight and as you can see the Rain Duration sensor picked up the rain long before the rain bucket tipped, so from this you can actually see the benefit of having the Rain Duration sensor