6 replies to this topic

[khodds]

Hi there,

I set up my new WS yesterday, but im not convinced about the positioning of my temperature sensor. I have put it up in the eaves of the garage which is adjoined to the house. The reason I'm not sure its positioned correctly is that there was a 2 degree difference in temperature between my ws and my car. The car read 3*c and the sensor read 5.8*c. What do you all think? I live in a bungalow so the sensor is at around 2 meters height.

Thanks

[4wd]

It's not ideal, you'll get some heat from the house and the 'correct' height is four feet and shielded but in an open area (so far as possible)
The car will be reading too low though - the metal radiates heat and the onboard thermometer will be closer to what a thermometer would show on the grass.
I would leave it for now unless you have a realistic plan B.

At the end of the day you're recording temperatures 'at your house' and comparing that location primarily with previous months years at that location so it's not desperately important to be close to other stations nearby or whatever.
Almost all Personal Weather Stations have some degree of compromise unless you have a 5 acre field with fenced off area in the open, away from the house.

[wimblettben]

Ultimately its up to you where you place your temperature sensor. Bare in mind though that most meterological stations wan't to only record the temperature of the air, and not the temperature of the suns rays.

It isn't important really whether you wan't to record the air temperature or the sun and air together, but if you were reporting for the Met Office for example then you would have to find a suitable location so that the sensor would only record the temperature of the air and not the sun or heat from nearby objects. Best way to do this would be to place it under a tree or ideally in a Stevenson screen if you can afford it as most are exspensive.

[Terminal Moraine]

The alternative to a Stevenson Screen would be to buy a mini screen and mount it on a post in the garden, however the practicality of this does depend on the type of sensor you have as the mini screens I've seen are designed to house a small torpedo shaped sensor at the end of a thin cable.
It also depends on your finances as it wouldn't really be worth spending about £50 on a mini screen if you've only paid £25 for a whole weather station.
It is likely that the current positioning of the sensor would cause it give higher values than if it was situated in the shade in the open at 1.2m above the ground. You'll definitely be getting secondary radiation from the building, particularly so in summer, and the minimum temperatures will be higher than otherwise due to a combination of secondary radiation and increased height above the ground.
As 4wd states above though, it's only a real problem if you want to compare your readings with those of other stations whose instruments/sensors are positioned more closely to the Met' Office ideal.

[Miguel Hugo Roberto]

If it helps, mine is currently mounted on a north-facing wooden fence, about 4ft off the ground, partly sheltered by a hedge on two sides of it.

[khodds]

Thanks for all your replies, I'm going to leave it where it is for the time being. We are due a frost on Sunday I believe, I'll see what it says then.

[khodds]

I have now moved it onto a north facing side of our shed, under the eaves, as there was a frost last night and the reading only went down to 3.3c where it was originally positioned..