Answer:
The hairs would have acquired charge by the passing of dry winds resulting in the loss of electron.
Explanation:
While standing on the top of a mountain if a person gets its hairs stand up after a cloud passes over, this might happen due to the static electric charges on the lower surface of the cloud are opposite in nature to that of hairs which the hairs would have acquired by the passing of dry winds which would have resulted in the loss of electron from the hair tip.
Similar case happens when we rub a dry plastic ruler or a dry plastic comb on our hairs.