Munich in the haze: Weather phenomenon caused by aerosols causes cloudy visibility!

Munich in the haze: Weather phenomenon caused by aerosols causes cloudy visibility!

There is currently bright sunshine in Munich, making the city shine. But as dusk sets in, a milky veil passes over the city, clouding the view.
Christian Plaß-Dülmer from the Hohenpeißenberg Meteorological Observatory has now taken on the phenomenon. He explains that the reason for this special effect is the increase in organic aerosols in the ground layer. These aerosols, mixtures of gases and finely divided particles, collect in the air through a range of atmospheric conditions.

The total amount of aerosols in the upper atmosphere is not exceptionally high, but there is an increase in the lower air layers. The suspected sources for this are diverse: On the one hand, they probably come from the high emissions from vegetation, which increase as a consequence of rising temperatures after rainfall. On the other hand, forest fires from Spain, France and Canada could also contribute, as observed in June, when these fires produced a similar milky appearance.

Insights into aerosol research

Although Sahara dust is buzzing in people's minds as a possible cause, Plaß-Dülmer makes it clear that the optical properties and air currents do not match, so that it can be ruled out as the cause. The high pressure situation also contributes to the increase in the haze, as the aerosols can collect in the lower air layers. In addition, relatively high humidity could have caused the aerosol to swell further.

The good news is that no worrying increases in carbon dioxide or nitrogen oxides have been detected. There is only a moderate increase in carbon dioxide. This could rob the people of Munich of some sleep, but it should be kept within limits. The importance of understanding the connections between aerosols and weather phenomena is also reflected in the international studies on this topic. Studies carried out at CERN's CLOUD research center, for example, have provided detailed insights into the chemical reactions of organic compounds. This work could help further clarify how air composition affects local weather patterns.

In an experiment at the CLOUD, a special chamber with precisely defined conditions was used to analyze the chemical reactions of aromatic precursors. These experiments are part of extensive research that shows how a wide range of conditions, from temperatures to humidity, can influence aerosol formation. Various gases were used to observe the chemical reactions and gain a better understanding of the particle distribution.

Just as the weather situation in Munich is currently fluctuating, research into the causes of weather phenomena is no less dynamic. It remains exciting to see how these findings will impact future weather forecasts.

For anyone who would like to deal more intensively with this topic, we recommend articles and studies in the Süddeutsche Zeitung and the Nature. There you will find further interesting information about current research results and their effects on the weather.