Maybe it was a combination of both. Damage due to UV radiation in combination with mechanical load.
@hornychz During research with the ultrasonic anemometers I saw that the Netatmo anemometer comes for 90 EUR. This seems in comparison with the other available devices not so expensive. Could be a solution...
Edit: I found out that this topic was already discussed in the forum.
@hornychz During research with the ultrasonic anemometers I saw that the Netatmo anemometer comes for 90 EUR. This seems in comparison with the other available devices not so expensive. Could be a solution...
Edit: I found out that this topic was already discussed in the forum.

