By Dr Jasper Knight, PhD, University of The Witwatersrand — The Conversation, 31 January 2022
Snowfall in a hot desert may seem a contradiction, but snow has been recorded several times in the Sahara Desert over recent decades, most recently in January 2022. Although the Sahara commonly experiences very high temperatures (more than 50°C), low temperatures are also recorded — particularly at night — because of the bare land surface and cloudless skies. A maximum cold of -14°C was recorded in Algeria in January 2005.
In order for snow to form, two distinctive weather properties are needed: cold temperatures and moist air. Winter air circulation patterns draw cool, moist air towards the northern Sahara from the Atlantic and Mediterranean. Over higher ground — such as the Atlas Mountains of Morocco and Algeria — rising air can cool, condense, and if cold enough, its moisture can freeze to form snow crystals. The Atlas Mountains in particular act as a snowtrap because of their proximity to the Atlantic and their elevation. The Algerian town of Ain Sefra received snow in 1979, 2016, 2017, 2018, 2021 and 2022. Several ski resorts are found in the Atlas Mountains as evidence shows that snow falls relatively frequently there.
Is snow in the Sahara becoming more or less common? The short answer is that we don’t yet know, partly because of the lack of historical data and partly because climate modelling has not focused on the Sahara. Globally, climate change is leading to more unpredictable weather patterns. Snow events in the Atlas Mountains are likely to continue and may become more variable in timing and quantity. Meanwhile, the bigger climate threat to the Sahara is that its landward side will become drier, groundwater aquifers are being over-pumped, and the Sahara itself is growing as the southern Sahel turns to desert. This article has been republished under Creative Commons licence.