中国亚热带西部山区夜雨特征的农业气候学研究

AN AGROCLIMATIC STUDY ON NIGHT RAIN FEATURES IN MOUNTAINOUS REGIONS IN THE WESTERN PART OF SUBTROPICAL ZONE IN CHINA

This paper studies weather-climate features and laws of spatial and temporal distri-bution of night rains and advances the decrease or disappearance of topographic effect gradually with the rise of elevation and the night rainfall more than daytime rainfall in the middle-lower layers in mountainous regions. The more night rainfall is caused prin-cipally by both rainfall hours and rainfall density. The phenomenon of "clear in daytime and rain at night"appears in some mountains and altitudes. The night rain appears prin-cipally in growing seasons, especially in April to May of spring sowing and in July to August of autumn crop in the milk-filling and milk stage. According to the meteorologi-cal data(1989-1990) from stations in different sloping positions and altitudes above sea level. Monthly rainfall of both daytime and night and the rain days in mountainous re-gions in the western part of subtropical zone were counted. The night rain resources will become an important basis for preventing drought countermeasures in mountainous re-gions in the western part of subtropical zone.