副热带高压给西安城墙送来“限定皮肤”，专家解读背后原因

Core Points - Continuous rainy weather in Shaanxi Province since September has led to the growth of moss on sections of the Xi'an City Wall, particularly between Yongning Gate and Wenchang Gate, attracting public attention [1] - Experts indicate that the moss is only growing on the surface of the wall and does not penetrate deeply, thus not damaging the structural integrity of the wall [3] - The local meteorological department reported that the cumulative rainfall in many areas of Shaanxi has reached historical highs for this period, with six regional heavy rain events recorded, ranking second since 1961 [7] Weather Conditions - The persistent rainy weather is attributed to the stable presence of the subtropical high pressure in the Huaxi-Huanghuai region, with Shaanxi located in a warm and humid airflow zone, combined with multiple short-wave troughs from the westerly wind belt [5] - The local meteorological department forecasts intermittent rainfall in most of Shaanxi on the 15th, with a return to rain on the 16th and 17th, but a significant reduction in rainfall intensity is expected after the 20th [9]