Reference: Ultrasonic Anemometer, Anemometer, Carl47
This would also tell you the wind direction.
When using a set distance ultrasonic distance sensors sense the air motion. Not a doppler effect, but the same idea. First to find out how accurate would it be using a HC-SR04s. I have 200kHz ultrasonic transducers, I’d need to find out how to drive them and what I’d need to receive.
For multiple ultrasonic sensor considerations
http://maxbotix.com/articles/031.htm
Love it!