SAHARA IN LOWER SILESIA? SOMETIMES IT HAPPENS…
Yesterday and today there were reports in the media about a spectacular influx of Saharan dust over Europe. Due to the intense snowfall, the phenomenon was easy to observe, as the dust tinted the snow cover to a delicate sand-yellow color (such a layer is visible at the bottom of the snow profile in the title photo).
And how did this “guest” from warm countries affect the concentration of dust in our air? This is well illustrated by the comparison of PM2.5 and PM10 dust concentrations. Why these two fractions? Well, in winter our air is dominated (unfortunately) by soot from the combustion of solid fuels – these are small particles, most often with a diameter of less than 2.5 micrometers – i.e. they belong to the PM2.5 dust.
Mineral dust (this type includes desert dust, among others) are bigger particles – their size generally exceeds 2.5 micrometers. In the conditions of our country, this dust most often enters the air in summer, during drought, it rises from the dried ground under the influence of gusts of wind. In winter, when the weather is wet or snowy, there are generally no favorable conditions for mineral dust to rise from the ground, so there is very little of it in the air. Of course, the situation changes in exceptional cases, when guests from distant deserts visit us …
If we look at the attached graphs, we will see that on 06.02 PM2.5 dust constituted about 90% of PM10 dust – this is a typical winter situation (a lot of soot from combustion processes, negligible amounts of coarse mineral dust). However, during the night from 6 to 7 February, the situation clearly changed – the concentrations of PM10 increased significantly, the concentrations of PM2.5 remained more or less at the previous level. This phenomenon was recorded simultaneously throughout the region, indicating a common source of thicker dust fractions – the Saharan dust.
The author of the article is Tymoteusz Sawiński PhD from the Department of Climatology and Atmosphere Protection.
The text comes from the Life-Mappingair / Pl website