Cows standing in a circle is well known to originate from ancient celtic times, when they all paid homage to the sun and moon gods. What you have observed is amost certainly a vestage of these ancient ceremony and nothing to do with wind direction. Of more concern is that some herds have begun to exhibit positive antagonism to increased aircraft movements in certain areas, particularly the south east and there is concern that they deliberately point in the wrong direction to confuse aircraft. There have been a couple of arrests for endangering aircraft, the offenders have been suitably punished and are now occupying several shelves in their local Tescos