Wind sensors: Propeller vs Rotating cups

I made an interesting observation the other day. I have two wind sensors on the same mast located 33 feet above the ground. One is a rotating-cup type, the other is a propeller type.

During the same wind storm, the propeller type consistently logged higher peak gust speeds, while the average speeds were nearly the same. The highest peak for the day was 54.7 MPH on the propeller and 47.5 MPH on the rotating cups, both recorded the same minute.

Both wind sensors are made by LaCrosse.

My theory is that the propeller has less rotating mass (less inertia to overcome) and therefore can accelerate more quickly. This makes the propeller type more responsive to sudden, short-term gusts.

Does that make sense? Has anyone else experienced similar results?

Knowing LaCrosse… neither measurement was accurate. #-o

(Hey look, I’m a Davis snob now!)

Those are significant differences. Is the cup anemometer level? I’m wondering if it has something to do with the angle of attack of the wind on the anemometer? Just speculating here… :? Could be something completely different. :frowning:

I have a La Crosse WS3610 (propeller wind) and an AAG Wind Sensor (cup). I noticed that generally speaking the La Crosse wind speed reads a bit higher than the AAG on current wind speed. The other day the La Crosse recorded a gust of 65 mph and the AAG recorded 35 mph.

Bill