Second, temperatures must be cold enough to form Pscs.
State Pscs conduct periodic and special exams as per requirement.
This is useful for all Civil Services exams- UPSC and State Pscs.
During winter, even though Pscs are at their most abundant,
there is no light over the pole to drive chemical reactions.
During the last week of January, however, a major warming event sent temperatures well above normal-
much too warm to support Pscs.
The Cl-catalyzed ozone depletion can take place in
the gas phase, but it is dramatically enhanced in the presence of polar stratospheric clouds Pscs.
Pscs were abundant over many high-latitude areas until dissipated by a big warming event,
which started in the upper stratosphere during February and spread throughout the Arctic stratosphere in March.
These clouds also contribute to ozone depletion over Antarctica,
as reactions on the surfaces of solid and liquid Pscs can significantly increase the abundance of the most reactive chlorine gases.