Question

Q. What are the polar stratospheric cloud?

Answer 1

in winter near the North or South Pole, temperatures in the lower stratosphere get that cold. That's when PSCs can form. POLAR STRATOSPHERIC CLOUDS

Answer 2

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Polar stratospheric clouds are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 m. They are best observed during civil twilight, when the Sun is between 1 and 6 degrees below the horizon, as well as in winter and in more northerly latitudes.