Three facts about fog in autumn

Fog is a constant companion of autumn

Fog occurs when visibility is less than a kilometer, according to MeteoSwiss. Fog is especially common during the autumn months, so fog can be expected every three days in October. In high altitude areas, foggy days are much rarer.

Three facts about fog

1. Less than 1 kilometer clear vision:
   If at some point in the day you can no longer see, or at least more than a mile, it is considered a foggy day. On the other hand, if the visibility is up to four kilometers, it is considered haze.
2. Almost the fifth less foggy day:
   Climate change doesn’t stop at foggy days either: From 1971 to 1990 there was an average of 30 foggy days a year in central Switzerland. In the measurement period from 1995 to 2014, it was only 25 days – a decrease of almost a fifth.
3. A droplet measures 10–40 μm, i.e. micrometer:
   Fog is water vapor of the smallest droplets, usually only 10 to 20 mm, i.e. a thousandth of a millimeter. Because they evenly scatter the light refracted by them, in fact the transparent droplets appear collectively as white or grayish.

Disadvantages of fog

During the winter, fog is a significant burden for most of the lowland inhabitants and affects their well-being. Also, fog is important to other areas of daily life. For example, visual impairment also affects road safety. Also, fog formation is closely linked to air hygiene aspects: in foggy weather conditions, air exchange in the lower atmosphere is severely restricted. As a result, pollutants such as fine dust can accumulate and reach concentrations dangerous to health.