气象部门解读北京今年首场降雪为何“分配不均”

Core Viewpoint - The recent snowfall in Beijing is attributed to a typical backflow snowfall pattern in North China, resulting in significant snow accumulation in various districts, particularly in the western mountainous areas [4][6]. Group 1: Snowfall Data - The average snowfall in Beijing from January 17 to January 18 was 1.2 mm, with an average of 1.6 mm in urban areas and a maximum of 9.9 mm recorded in Fengtai District [1]. - Snow accumulation in areas such as Fangshan, Mentougou, Shijingshan, Haidian, and Fengtai reached depths of 9 cm to 20 cm [2]. Group 2: Meteorological Explanation - The snowfall was caused by an easterly cold air flow from the Bohai Bay, which brought moisture to Beijing, leading to the formation of snow clouds at temperatures between -10°C and -20°C [4]. - The structure of the snowflakes was fluffy, contributing to the visual effect of "feather-like snow" and resulting in thicker snow accumulation [4]. Group 3: Regional Variations - The western mountainous areas of Beijing experienced greater snowfall due to the terrain enhancing the uplift of the easterly winds and moisture [6]. - The snowfall distribution was uneven, with significant snowfall occurring in the western regions during the evening and night of January 17 [6].