日照百分率，即实际日照时间与可能日照时间（全天无云时应有的日照时数）之比。它表明了气候条件（主要是云、雨、雾、尘、沙等）减少了多少日照时间（%）。
年日照百分率呈双波型变化。
本文根据日照百分率年变程曲线类型，应用聚类分析方法，把全国划分为12个日照区。
By using the method of cluster analysis, the annual variation curve types of the sunshine percentage in China are divided into 12 divisions.
主要研究结论如下：（1）1951-2008年，年和生长季的日照时数及日照百分率均呈减少趋势。
The main research achievements are as follows:There was a decreasing trend of the sunshine duration and sunshine percentage of year and growing season from 1951 to 2008.
应用推荐