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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2026-06-11 23:58 |
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Conference: Bucharest University Faculty of Physics 2026 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Fog Microphysics Variability and Visibility Relationships in an Urban Environment: Observations from Bucharest
Authors:
Alex Vlad (1,2), Bogdan Antonescu (1,3), Sorin Nicolae Vâjâiac (1), Gabriela Iorga (4,1)
*
Affiliation:
1) Faculty of Physics, University of Bucharest, 077125 Bucharest-Magurele,Romania
2) National Institute for Aerospace Research “Elie Carafoli” – INCAS, Bucharest, Romania
3)National Institute for Earth Physics, 077125 Bucharest-Magurele,Romania
4)Faculty of Chemistry, University of Bucharest, 030018 Bucharest,Romania
E-mail
vlad.florentinalex@gmail.com
Keywords:
fog microphysics, visibility, urban aerosols, in situ measurments, aviation meteorology
Abstract:
Fog is a low-level cloud forming in direct contact with the Earth’s surface, consisting of suspended water droplets or ice particles that significantly reduce near-surface visibility. According to meteorological criteria, fog occurs when horizontal visibility decreases below 1 km due to the scattering and absorption of light by these particles. Beyond its impact on visibility, fog plays an important role in the Earth system by modifying the surface radiation budget, contributing to daytime cooling and nighttime warming. Furthermore, fog represents a major hazard for terrestrial, maritime, and particularly aviation transport, where reduced visibility can substantially affect the operational safety.This study investigates the variability of fog microphysical properties and their relationship with horizontal visibility under urban atmospheric conditions. The analysis is based on continuous in situ measurements collected during the winter season of 2025–2026 in Bucharest, Romania, using a Fog Monitor FM-120. Concurrent meteorological observations, including air temperature, atmospheric pressure, relative humidity, wind speed, and wind direction, were obtained using a Lufft WS600-UMB weather station. Measurements were conducted at the National Institute for Aerospace Research in Bucharest, an urban location strongly influenced by road traffic and anthropogenic aerosol emissions, potentially providing abundant condensation nuclei for fog formation. The analysis focuses on key fog microphysical parameters, including droplet number concentration (N), effective diameter (ED), liquid water content (LWC), and mean volume diameter (MVD), within a particle size range of 2–50 μm. The observational dataset is further employed to evaluate multiple fog visibility parameterizations in order to identify the most suitable relationship between fog microphysics and visibility for the Bucharest urban environment.The findings contribute to the growing body of research on fog characterization and regional visibility parameterization, supporting a better understanding of fog formation processes and potentially improving visibility forecasting and operational safety in transportation sectors, particularly aviation.
Acknowledgement:
AV was supported by the University of Bucharest, PhD research grant. AV was supported by the Romanian Ministry of Research, Innovation and Digitalization (National Research Authority) under Contract no. 36N/12.01.2023, within the project "PN – Advanced Research to Increase Competitiveness and Capacity for Design, Analysis and Specific Expertise in the Aerospace Field – AEROEXPERT 2023–2026", project code 23 17 08 01, entitled "Development of Technological Capabilities in Support of Earth Monitoring and Environmental Activities".
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