Understand the phenomenon that turned snow orange in Europe; see images

An exceptionally rare haze of Saharan dust blanketed Switzerland and southeastern France this weekend, prompting public health warnings as a yellow hue tinted the sky. The dust turned the snow orange in the Alps. The phenomenon, which began on Friday in Switzerland, brings with it “a very clear deterioration in sunlight and visibility. Added to this is an increase in concentrations of fine particles,” weather service MeteoSuisse posted on X.

With dust concentrated at less than 3,000 meters altitude, air quality was particularly affected, with air quality monitoring indicating high levels of particulate matter in the atmosphere. Calculations estimate that the amount of dust reached around 180,000 tonnes, double the levels recorded during recent similar events, said Roman Brogli, meteorologist at SRF Meteo.

In neighboring France, local authorities in the Southeast and South announced that the air pollution limit had been exceeded on Saturday, with the department of Herault asking residents to avoid intense physical exertion, especially those with heart or respiratory problems.

The Saharan dust cloud turned snow orange in mountains and at ski resorts in Italy, France and Switzerland, especially in the Alps region. Although it is a natural phenomenon that has already occurred, this episode was more intense than the previous ones.

The Sahara desert releases 60 to 200 million tons of mineral dust per year. While larger particles quickly return to Earth, smaller ones can travel thousands of kilometers. A wind called Sirco transports particulate matter from the desert to the European continent.

Sand gives snow an orange hue and can affect melting processes, notably in glaciers, which are shrinking as average temperatures rise, reducing the ice’s ability to reflect sunlight. The situation improved in France and Switzerland this Sunday.

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