...we often find our country. This is because in the “Czech basin surrounded by mountains”, fog is a relatively frequent phenomenon, in part because of the geomorphology. We talk about fog when a cloud of suspension of water droplets reduces the visibility to less than one kilometer in at least one direction. If the visibility is from 1 to 2 km, it is called mist and from 2 to 5 kilometers, haze. The most intense fog in terms of visibility and density is found in the mountains, where they also have a significant impact on the water balance, so we can talk about a major influence on the mountain ecosystem. In the lowlands, fog does not occur as often. In urban agglomerations, however, the occurrence of condensation nuclei formed by aerosol particles with radii from 10-8 to 10-5 support its occurrence. At the same time, the high levels of pollutants present a great danger. Individual places in Czechia differ not only in intensity, range and type, but also in the fog frequency, from only tens of days to almost 300 days a year. Several studies from different parts of Europe show a decrease in fog frequency due to either climate change or an improvement of the ambient air quality. And how does the long-term trend look in our territory? A group of scientists under the leadership of Iva Hůnová from the Institute for Environmental Studies is dealing with the question.
Published Mar 25, 2019