Nacreous clouds, nacre clouds or polar stratospheric clouds (abbreviated: PSC) can only be seen in the winter, at an altitude of 15,000 - 25,000 m.
Only some places on earth can see nacre clouds such as Iceland, Northern Canada, Alaska, Northern Europe and Antarctic countries.After sunset or before dawn, fuzzy clouds with vivid colors can form on the dark sunset sky.
Nacreous clouds are made up of a natural mixture of water and nitric acid coming from industrial emissions.
In the past, we used chlorofluorocarbon (CFC) substances in spray cans and cold heat.This chemical has been removed but still exists today.After a few years, the CFC evaporates and moves through the troposphere to the stratosphere.Here, they are decomposed by ultraviolet light and produce free chlorine atoms that destroy the ozone layer, the shield needed to protect us from the sun's harmful rays.
Winter in extremely long regions and with little sunlight, low temperature ants let nacre clouds begin to form in the stratosphere even though the air is very dry.
Nacre clouds produce frozen crystals of water, nitric acid and sulfuric acid sometimes, providing an ideal surface for chemical reactions to occur to release free chlorine atoms back gas.
The presence of sunlight is essential to balance, so this only happens in the spring when returning, when sunlight reaches the polar regions, and ultraviolet light will disrupt the link between chlorine atoms.This process can only be stopped once nacre clouds are destroyed by low-latitude air currents.
Such chemical reactions cannot occur anywhere else in the atmosphere.
This explains why the size of the ozone layer in the polar regions is often larger than in other places.
In addition, nacre clouds often appear more in the southern hemisphere.Thus, the ozone layer in the southernmost is more exhausted than the north pole.