A very localized phenomenon linked to pollution. If some inhabitants of Indre or Haute-Garonne had the pleasant surprise to wake up to a landscape covered in white on Saturday 13 January.
Indeed, the people who have been able to benefit from this small white film are those living near an industrial area or a highway, hence the name "industrial snow". This phenomenon is linked to the combination of specific winter weather conditions and human activities. More specifically, they are observed when the humidity level in the air is high, coupled with temperatures close to zero degrees, the absence of wind and the presence of airborne pollution particles.
" READ ALSOWeather: some snowfall expected from Île-de-France to the Grand Est
While these conditions are often synonymous with stubborn fog and stratus clouds in the plains and valleys, it is human activity that produces this snow. "Pollution related to industries, traffic, heating appliances charges the ambient air with additional humidity but also small solid particles called condensation nuclei," explains Météo France. It is then that "in sub-zero temperatures and in the absence of wind, water vapour attaches itself to these cores, freezes and turns into snow," says the meteorological service.
Snowfall difficult to predict
In the district of Saint-Simon, in Toulouse (Haute-Garonne), this snow also called "pollution" fell due to the presence of the Mirail incinerator, the most polluting in France. This explains why these areas where industrial snow falls are very localized.
In Châteauroux (Indre), the same phenomenon was observed in the south-west of the city. In an aerial photo taken by the Châteauroux Villers flying club and shared by the Association Météo Centre sur X, we can observe a glaring difference between the area where the industrial snow fell and the one where it did not.
Another telling photo of this industrial #neige phenomenon to #Châteauroux last night! pic.twitter.com/tJTCHPJ2vm
— Weather Centre Association (@AssoMeteoCentre) January 14, 2024
In its publication, the Association Météo France also explains that these low snowfalls are "difficult or even impossible" to predict, as emissions from factories and transport are not taken into account in weather models. In addition, "it is difficult to predict the persistence of cold and humid anticyclonic conditions necessary for its formation," says Météo France.