直射点
直射点-
日落的持续时间在春季和夏季最短（在这些时候太阳直射点在赤道上方），在至日和春分（秋分）的时候最长。
It 's shortest in spring and fall ( when the Sun is over the equator ) and longest in the summer and winter .
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模式模拟获得的全球季节平均和年平均感热通量与潜热通量显示地表通量的空间分布与太阳直射点的移动以及大气干湿度的空间分布存在直接关联。
The spatial distribution of simulated global seasonal and annual averaged sensible and latent heat flux to the surface flux had direct correlations with the noon solar altitude and atmospheric humidity .