2020, 2021 and 2022 are being some pretty crazy years; marked, to begin with, by a global pandemic. For this reason, we think that many extreme phenomena are the result of the apocalypse that seems to be approaching. In meteorologyIn fact, we do not fall short with these phenomena. Rays almost as extensive as the entire Iberian Peninsula, iguana rainsa storm that last year covered in white areas of Spain that hardly remembered snow… And now, as if all that were not enough, comes the snow in the Sahara desert.
It sounds like a disaster, but the truth is that we are now so vigilant that even the simplest thing can seem like an exception. Snow in this part of the world is rare, yes. But It’s not at all unusual. In fact, it is not even clear that the climate change is worsening the situation, as explained in The Conversation the physical geography teacher Jasper Knight.
But then why does it happen? How can it be that a place so dry and warm like the Sahara desert experiences snowfall from time to time? Well, basically, for something very simple. Because it is not always dry and warm.
Hot during the day and cold at night
Deserts in general, not only the Sahara desert, are characterized by very high temperatures during the day, but much lower at night.
This is mainly due to two reasons. On one side, to its bare surface, hardly any vegetation. They are usually basically covered by sand, which absorbs heat from solar radiation and immediately releases it into the surrounding air, but is not efficient at retaining it. For this reason, while the sun shines on it, temperatures are very high, but as soon as it hides below the horizon, temperatures plummet.
Now, this is not the only factor. Remember that on tropical beaches there is also only sand and the temperature remains high at night. But there the humidity is high. And in deserts, generally, the air is very dry. If there is water in the form of vapor in the air, more energy is needed to heat it, but also the other way around, for it to dissipate. However, when the air is dry, there is nothing to cushion those temperature changes.
Now, if we have said that the air is dry and for there to be snowfalls, humidity is needed, what is the reason for the snow in the Sahara desert?
The causes of snow in the Sahara desert
As Knight explains in his article, moist air comes from the Atlantic Ocean, the Mediterranean Sea and the Indian Ocean, by low pressure cyclones in the north of the Sahara during the winter and monsoon rains in the south during the summer. Therefore, although the center of the desert is very arid, humidity can accumulate on its periphery.
Besides, the atlas mountain range, higher than the rest of the desert and very close to the Atlantic, acts as a trap for that humid air. For this reason, this is the area where snow is usually concentrated in the Sahara desert. Since records began in the 1970s, there has been snowfall in 1979, 2016, 2017, 2018, 2021 and now in 2022. This last one, which occurred in January, has been very light, nothing to do with the intense snowfall of 2018, in which up to 30 centimeters of snow were reached.
In fact, a curious fact is that in the Atlas there are some ski resorts. Yes, they normally use artificial snow, but if they are there it is because they know that sometimes the real thing arrives.
But even so, it is striking that there were 27 years without snow in the Sahara desert and then there were so many snowfalls in a row. This leads us to think that climate change may have had something to do with it. However, the expert explains that it is not easy to know, basically because there is no data.
Being a very extensive and sparsely populated area for a long time there was no weather tracking. now there is satellites attentive to what happens in the region, but there is a period of history not too distant that is unknown. It could be interesting to collect testimonials, after all, not so long ago. Or even anthropological evidence for older times. But so far this has not been done, so it is not possible to know if climate change is a trigger for the frequency of snow in the Sahara. What we do know is that it triggers many other things, so there are plenty of reasons to fight it.