How do 2D anemometers differ from 3D anemometers?

A 2D anemometer, also called a 2D ultrasonic wind sensor, measures the horizontal parts of wind speed and direction.hat is the difference between 2D and 3D anemometer?
A 2D anemometer, also called a 2D ultrasonic wind sensor, measures the horizontal parts of wind speed and direction.hat is the difference between 2D and 3D anemometer?