Abstract:
Fog and low stratus clouds (FLS) form as a result of complex interactions of multiple factors in
the atmosphere and at the land surface and impact both the anthropogenic and natural environments. Here, we
analyze the role of synoptic conditions and aerosol loading on FLS occurrence and persistence in the Po valley
in northern Italy. By applying k‐means clustering to reanalysis data, we find that FLS formation in the Po valley
is either based on radiative processes or moisture advection from the Mediterranean sea. Satellite‐based data on
FLS persistence shows longer persistence of radiatively formed FLS events, likely due to air mass stagnation
and a temperature inversion. Ground‐based aerosol optical depth observations further reveal that FLS event
duration is significantly higher under high aerosol loading. The results underline the combined effect of
topography, moisture advection and aerosol loading on the FLS life cycle in the Po valley.
