Yes Whirly you are right.
Wind shear and sudden gusts will be evident in airspeed fluctuation's.
Try throwing your rubber ducky in a fast moving stream and watching it react to sudden changes in the water flow in rapids and sharp changes of the direction of the flow.
Your helicopter like the rubber ducky will react in the same manner in the fluid called air.
Just as the ducky changes velocity, direction and bobs up and down so will your helicopter. If the ducky was powered his / her speed also would change in relation to the changes in the water speed.... and the change would be evident as it reacts to the sudden changes in water flow speed, once established in a new flow speed the indicated speed will recover to the same as before the sudder change in the fluid speed..
Jeesees I,m getting myself confused...but I'm sure you get the drift? get it? drift? rubber ducky down stream? He HE HE
Chuck