A few weeks now I run my own weather station, a Ultimeter2100 from Peet Bros. At least once a day I check my weather data against that from the neighboring Royal Dutch Meteorological Institute (KNMI). It turns out that my temperature readings are off a few degrees (too high) only in the morning. Which is not surprising when you consider my temperature sensor is attached to our chimney. This turn out to be the only place that has shade almost all day. Almost… But not in the early morning (only if the sun shines).
It seems I’m in need of a UV-shield for my temperature sensor. After visiting the local DIY-shop I sawed, I glued and painted… Some people asked me if I had build me a nice bird-residence, but no. It is an UV-shield! It’s a familiar construction for this application: because the strips overlap each other, the sun can not shine between. But the air can flow freely around the sensor. Which has two advantages: no warming up of the sensor by sun rays and no fast cooling down by water drops on the sensor when it rains.
My second comparing of data turned out way better, my UV-shield seems to work.