Christmas Lighting and Its Impact on the Brightness of the Night Sky: A Case Study of Funchal

The Christmas period reshapes urban cultural experience by temporarily suspending everyday routines and placing collective celebration at the centre of public space. During this time, festive illuminations transform cities, intensifying the symbolic role of light and reinforcing seasonal rituals of exceptionality. In many European cities, large-scale decorative lighting is used not only for aesthetic enhancement but also to create distinctive urban atmospheres. This study examines the effects of seasonal festive lighting on light pollution and perceptions of urban space, using Funchal (Madeira, Portugal) as a case study. Combining in situ photometric measurements, satellite-derived night-time data, and a questionnaire-based perception survey, this mixed-methods study compares periods when festive lighting was active and inactive. The results indicate that Christmas lighting was associated with higher levels of artificial illumination, shifts in the spatial distribution of artificial light at night (ALAN), and changes in night-sky brightness. These findings suggest that festive lighting shapes both the visual character of urban space and the seasonal dynamics of light pollution.