Factors Encouraging more ozone depletion over Polar Regions:

Winter:

Severe drop in stratosphere temperatures = strong circular winds will form (aka polar vortex)
Vortex prevents warmer air from entering
Total Darknesses at the poles (keeps temperature extremely low and maintains the polar vortex)
Polar Vortex + Extremely cold conditions promote formation of polar stratospheric clouds over the poles (formation of ice crystals, compounds with Cl (HCl and ClONO2) trapped inside the crystals
Surfaces of ice crystals act as catalysts for the formation of Cl2

Spring:

More sunlight available in spring
Therefore: Cl2 molecules start to photo-dissociate from CFCs in the stratosphere
Rate of ozone depletion increases

Summertime:

	Created by IBMichelle about 10 years ago

IB Chemistry (E: Environmental Science (UNMODIFIED)) Note on E9: Ozone Depletion HL (UNMODIFIED), created by IBMichelle on 07/04/2014.