Let's suppose that an airplane flying at a uniform airspeed follows a perfect, level, closed circular trajectory with respect to the mass of air. Now, seen from the ground, and in the presence of a constant wind, will no longer be a circumference. What would it be...?
It will be this :
Pilot's of slow-flying aircraft like hang gliders and paragliders see tracks like these all the time on their GPS displays, as they circle in a thermal updraft in the presence of strong wind.
Depending on the strength of the wind, the "curliques" may become so stretched out that they don't form enclosed loops at all, just "points", i.e. a "scalloped" line. This happens when the windspeed is greater than the airspeed. That means that the aircraft never makes any progress in the upwind direction at any point in the circle.