平均太阳日

恒星日比平均太阳日短三分五十六秒。

A sidereal day is shorter than a mean solar day by 3 minutes and 56 seconds .

本文计算了北京地区四种弧型采光屋面的温室内10～4月各月平均太阳直接辐射日总量（简称直射光总量），并进行了比较。

In this paper , we calculated and compared the mean daily amount of direct solar radiation of each month from October to April in four types of greenhouse in Beijing region . Each type of these greenhouses has its specific arc lighting surface .

主分量分析和偏相关分析表明，影响树干径向生长的气象因子可划分为3类，其中日降雨量、日最低气温、日平均太阳辐射和日平均空气饱和差是影响树干径向生长的主要因子。

Principle Component Analysis and Partial Correlation Analysis indicated that the meteorological factors could be classified into three groups , and daily precipitation , minimum daily temperature , average daily solar radiation and average daily vapor pressure deficit were four significant factors to determine daily stem growth .