Ozone is a form of oxygen with the chemical formula O3 that is formed when O2 is affected by UV radiation from Sunlight. What is there very little of over the poles during the winter periods? You know that - Sunlight.
I created the ozone hole with the Van de Graaff generator I made as a 7th grade Science Project!
True that. Most of the ozone creation however occurs in the equatorial region where sunlight is strongest. It then moves via the stratosphere toward the poles. The polar ozone hole sizes, always were a function of the amount of ozone creation at the equator. Scientists assumed it was a constant. Very big mistake.