Munich in the haze: Where does the mysterious veil come from?

Munich in the haze: Where does the mysterious veil come from?

Bright sunshine has reigned over Munich in the last few days, and the sky was cloudless. In the evening, however, a veil falls over the city, clouding the view and bathing the sunset in soft colors. Christian Plaß-Dülmer from the Hohenpeißenberg Meteorological Observatory has now provided clarification on this phenomenon. [Süddeutsche] reports that an increase in organic aerosols was found in the ground layer, which could be responsible for the haze.

Aerosols, which are tiny particles of gas and solid material, are often difficult to determine. Their origins sometimes remain unclear. The total amount of aerosols in the atmosphere is not noticeably high, but there is an increase near the ground that has been observed to be related to the high temperatures following recent rainfall. In addition, regional forest fires from Spain, France and Canada may have left their mark. This haze was already caused by forest fires in Canada last June, which resulted in a milky haze.

Causes and influences

Interestingly, Saharan dust has been ruled out as the cause of the currently noticeable haze. The necessary optical properties and air flows conflict with this. However, a dominant proportion of dust in the air has recently been detected. A high-pressure situation further increases this effect because it concentrates the aerosol in lower air layers and can cause the particles to swell when the air humidity is high.

Although experts have ruled out worrying increases in carbon dioxide or nitrogen oxides, there is a moderate increase in carbon dioxide in the air. [Nature] also points out that forest fires in the Euro-Mediterranean region may have an additional impact on fine dust concentrations, which is confirmed by several studies. These include studies by Majdi et al. and Sofiev et al., who examine the impact of wildfires on air quality.

Long-term effects on air quality

Air quality monitoring measures are currently in focus. Kuenen et al. reported on the development of an emissions inventory that is intended to provide consistent data for air quality models. These also receive support from modern techniques, such as the aerosol mass spectrometer, which is used in various studies.

We can't wait to see what further developments happen on this front. The adaptations and new technologies in air quality research could be important not only for urban areas, but also for the health of populations in urban and rural areas worldwide. Given the changing air conditions, it is essential to have a good sense of the sources and quality of the air we breathe.