DSST Environmental Science Practice Exam 2025 - Free Environmental Science Practice Questions and Study Guide

Polar stratospheric clouds (PSCs) form under very specific atmospheric conditions. The primary requirement for their formation is extremely low temperatures, typically occurring in the stratosphere over polar regions during winter. When temperatures drop below approximately -80 degrees Celsius, the conditions become favorable for the formation of these clouds.

At such low temperatures, water vapor and other trace gases can condense, forming clouds composed of ice particles and polar stratospheric cloud crystals. These clouds play a significant role in the depletion of the ozone layer, particularly during the spring when sunlight returns to the polar regions, triggering chemical reactions that break down ozone.

In contrast, temperatures above -60 degrees Celsius are not conducive to the formation of these clouds, as the necessary condensation of gases into solid or liquid form cannot occur. Solar maximum and summer solstice also do not directly relate to the formation of PSCs, since these events typically correlate with increased solar activity and warmer temperatures, neither of which support the extreme cold necessary for polar stratospheric cloud development.