Munich in the haze: What causes the milky sunsets?

Munich in the haze: What causes the milky sunsets?

In Munich you are currently enjoying a wonderful summer with bright sunshine and hardly any clouds in the sky. But in the evening a milky veil falls over the city, which amazes many Munich residents. Christian Plaß-Dülmer from the Hohenpeißenberg Meteorological Observatory has investigated the causes of this fascinating weather phenomenon and shed light on how the increase in organic aerosols in the air layer near the ground is related to the beautiful sunsets. South Germans reports his findings, which point to a combination of various factors.

Aerosols, a mixture of gas and fine particles, are the main cause of this haze. However, the exact origin of the cloudy particles is difficult to determine. Plaß-Dülmer explains that although the total amount of aerosols in the atmosphere is not unusually high, their proportion increases near the ground. He sees the most likely sources as the high emissions from vegetation, caused by increased temperatures after recent rainfall. There are also possible contributions from forest fires from distant regions such as Spain, France and Canada.

Global connections

The problem with aerosols is by no means just a local phenomenon. In June, forest fires in Canada resulted in a similar milky haze. These fine particles not only influence local air quality, but also have an impact on the global climate. Studies show that organic aerosols from biomass combustion and vegetation are particularly responsible for changes in air quality. Numerous research results, such as those by Majdi et al. (2019) and Chen et al. (2022), underline the role of forest fires and their emissions in the Euro-Mediterranean region, which are associated with particulate matter. Nature highlights the importance of more accurate source attribution in order to develop targeted strategies to improve air quality.

A high pressure area increases the haze as the aerosols collect in the lower layers of the air. This could have caused the aerosol to swell further, especially in combination with relatively high humidity. Despite these assessments, however, there is an all-clear: According to the meteorologist, there is no worrying increase in carbon dioxide or nitrogen oxides in the air, only a moderate increase in carbon dioxide has been detected.

What does this mean for the people of Munich?

For the people of Munich, the situation remains an exciting natural spectacle - the evening atmosphere is made unique by the milky twilight. But it also shows that behind this beautiful sight there are complex climatic and environmental processes that play a role worldwide. The balance between pleasant weather and air quality challenges remains an important issue that needs to be discussed not only locally but also globally. The key is to show a good hand at monitoring and improving air quality so that you can continue to enjoy the blooming summer evenings to the fullest in the future.