There Is a Desert That Gets Snow

While we picture deserts as eternally scorching landscapes, their defining trait is actually a lack of precipitation, not constant heat. This is why snow can, on rare occasions, blanket the iconic orange dunes of the Sahara. For snow to form, two conditions must be met: freezing temperatures and atmospheric moisture. Parts of the Sahara, such as the Algerian town of Ain Sefra, are located at high altitudes in the Atlas Mountains. This elevation allows winter temperatures to drop below freezing, especially overnight, satisfying the first condition.

The second ingredient, moisture, is the truly rare element. The Sahara's dry air is precisely why it experiences such dramatic temperature swings; with no humidity to trap warmth, the day's heat rapidly escapes into the atmosphere after sunset. For snow to fall, an unusual weather pattern must occur, typically a low-pressure system from the North Atlantic or Mediterranean pushing much farther south than normal. When this cold, moist air mass moves over the freezing high-altitude desert, it can produce a stunning, albeit temporary, snowfall. The 2018 event was one of several in recent years, with the first widely photographed occurrence in that region happening back in 1979.