Re: What piece of equipment is used to measure wind?

Wind velocity is measured by use of a pitot tube.  It is essentially an open 
tube that is held perpendicular to the wind direction.  The other side of 
the tube measures the decrease in pressure due to the flow over the open 
side.  It uses basic bernoulli principles to calculate the wind velocity 
necessary to create the decrease in pressure.

[Moderator note:  There are other types of anemometers. One common type uses 
rotating "cups", with the frequency of rotation related to wind speed.]