The thalweg in loess hill area is an important terrain structural line, reflecting topography and landform character.

黄土丘陵区的沟沿线,是反映该区貌特征的重要的结构线。

Guangzhou is the rainstorm pilosity city of China.The climate, weather system, geographical position and topography are main factors of the rainstorm.

摘要广州是中国的暴雨多发城市，气候、天气系统、理是成暴雨的主要因素。

Such results are gotten: (1) Due to the unique topography the wind of Beijing area during the day time is southern anabatic wind and in the night is northern katabatic wind in summer.

(1)北京区域夏季边界层风场受西北特殊的影响,夜间低层大气流场常表现为由北向南的下坡风,白天逐渐转为由南往北的上坡风。