Related to propeller types
https://www.renewablenrgsystems.com/ser ... anemometer
Simply put, lift based devices with an air-foil such as wind turbines are affected by changes in air density, drag based devices such as cup anemometers are not affected by air density.
This is for tube types
https://en.wikipedia.org/wiki/Anemomete ... asurements
Effect of density on measurements
In the tube anemometer the dynamic pressure is actually being measured, although the scale is usually graduated as a velocity scale. If the actual air density differs from the calibration value, due to differing temperature, elevation or barometric pressure, a correction is required to obtain the actual wind speed. Approximately 1.5% (1.6% above 6,000 feet) should be added to the velocity recorded by a tube anemometer for each 1000 ft (5% for each kilometer) above sea-level.
Interesting
http://www.mdpi.com/1996-1073/5/3/683 https://www.researchgate.net/publicatio ... ir_Density
"I think" the answer "may" be in there. I mean
Deviation_of_Cup_and_Propeller_Anemometer_Calibration_Results_with_Air_Density 
Abstract
The effect of air density variations on the calibration constants of several models of anemometers has been analyzed. The analysis was based on a series of calibrations between March 2003 and February 2011. Results indicate a linear behavior of both calibration constants with the air density. The effect of changes in air density on the measured wind speed by an anemometer was also studied. The results suggest that there can be an important deviation of the measured wind speed with changes in air density from the one at which the anemometer was calibrated, and therefore the need to take this effect into account when calculating wind power estimations.
http://barani.biz/kb/air-density-change ... o-weather/
10% air density error due to Weather (temperature, pressure and humidity) may severely limit accuracy of your wind energy calculations rendering your anemometer accuracy irrelevant.
and some interesting calculations on density changes
Air Density Change Examples:
Relative Humidity change from 30% to 90% can change air density by 1% at 31°C (88°F). At 22°C (72°F) air density change is 0.6% and 0.4% at 15°C (59°F).
Air temperature change from winter to summer (5°C to 32°C, 41°F to 90°F) can change air density by as much as 10%.
Elevation height change of only 82 meters (270′ vertical feet) from sea level can change air density by 1%. (101325Pa -100344Pa =981 Pascals)
Weather front pressure changes range from 980 and 1050 hPa which corresponds to a 7% fluctuation in air density.
https://books.google.com/books?id=Zj4_v ... &q&f=false around page 135
books are great
?
Air density has an effect upon the threshold speed and distance constant of cup and
propeller anemometers. The threshold speed is inversely proportional to the density
because it represents a balance between the aerodynamic force and the friction forces
in the anemometer bearings.
What that means is density is more likely to change the wind reading at lower speeds like we are discussing. i.e. lower wind readings are more likely to represent actual wind power and not just speed.
ridiculous or not
