How does snow form and fall during cold depressions?

Weather of Arabia - Sinan Khalaf - Many countries around the world are exposed during the winter to strong depressions accompanied by cold air masses, which work on snowfall that may be with high accumulations and impeding life, and here this question imposes itself; How is snow formed?

First, it is necessary to point out some of the conditions that must be available for the formation of snow grains, such as plankton or any solid particles suspended in the air, where these particles, in turn, form a nucleus of water condensation around it and the cold air that works to freeze the water particles to form snow crystals that stick to each other forming snow grains. Which increases in weight and begins to fall towards the ground due to gravity.

The arrival of snow grains to the ground in their frozen form depends on the temperatures in the lower layers near the surface of the earth, which the lower they are, the more they prevent the melting of snow.

In the winter of each year, some regions of the Arab world are exposed to cold depressions that cause snowfall, in the highlands of Lebanon, Syria and Jordan, and some snowfalls may extend to the north of the Kingdom of Saudi Arabia and the highlands of Sinai in the Egyptian lands, as well as Algeria, whose heights are subject to semi-snowfall. annual.