Cumulus Support

the car sensor -8.4 when standing still westher station reading -4.4

I'm not sure how reliable these car sensors are.

I did a quick search of other readings in your area and they are showing -5C

I have doubted by station sensor a few times so I used another thermometer to check and it was right. If you doubt yours I would suggest getting another device to confirm your readings.

As Car sensors are mounted low down .usually on the bottom of the front bumper..... I would have expected a lower reading The closer to the ground the lower the ambient temp would be ( Especially if yer parked on Ice or Snow)

You can't really compare readings like that.

I have several thermometers outside.

At the present time the digital inside a Stevenson screen reads -4.2, the one outside the screen reads -2.6 and the remote WH1080 one 10 metres up reads -2.0.

It depends on the height and whether it's enclosed or shielded to the wind, etc.

A good calibrated mercury thermometer is probably the best to calibrate it with but it has to be in the same position as the remote WX station one.

Theoretically the outside temperature should be measured at around 2 Metres above ground level which may be impractical for many.

Mike.

With a temperature reading yesterday by mercury thermometer in the shade at the back of the house of -4C and the AWS sensor giving over +5C (with a home built extra screen similar to others shown here) I'm giving this more thought. The WS sensor is front/side of the house on the boundary with the field next door. There was very strong sunshine and no wind. I'm thinking the maybe the screen needs aspirating or I might build a standard type wooden Stevenson screen. In my view there's not much point in having a weather station if the readings are way off the mark.

I have the wind sensors on a mast about 10 ft above ground and the temperature sensor a couple of yards away on another post about 4ft above ground. The cable length from wind sensors to tx unit limits positioning.

I have the temperature sensor (and transmitter) on the north side of my shed, about 2 metres above ground (easy to get to when batteries need changing . No need for artificial aspiration or Stevenson: it matches quite well with other thermometers used for checking.

The rain sensor is attached firmly to the edge of the roof - within reach for the standard cable.
Anemometer etc. are up on a mast, and the cable has been extended using standard RJ-11/12 cable.

The Google map picture attached shows most of our property with the current location of the tx unit marked with a red dot (lower RH corner) and the mercury thermometer at north side of house shown in yellow. The wind sensors are on a 10ft pole just to the north of the red dot well clear of the small apple tree just north of that. This seems to be the clearest area for the most accurate wind measurements. The grass area to the north of the sheds is shielded with big trees and a barn to the west and north. There's a row of large oak trees to the west of the property.

As far as I can tell the current position has least wind turbulence and therefore best for wind and rain measurements. The rain gauge is about a couple of feet above grass and the tx/temperature/humidity unit on a post about 4ft or so above ground.

The ground rises to the north and west, and the area to the east and south is clear fields falling away to the river valley.