小时的阳光并不是唯一的因素,决定了日晒(太阳能在表面)。思想实验:铺床单在地板上,关掉灯,发光手电筒直接放在床单从一只脚上面。你会得到一个小的,相当的亮点的表。现在倾斜手电筒,照在它在一个平角——比如说,45或60度仍保持约一英尺远的地方照亮。当你平角度,伸长的覆盖面积越来越大。但的手电筒的光线仍然是相同的,分布在一个更大的区域,这就意味着低强度的表。相同数量的光曾触及100厘米2 <一口> < /一口>现货现在可能分布在500厘米2 <一口> < /一口>。这是发生了什么事的一部分在高纬度地区。在夏天他们得到许多小时的阳光,但是他们没有得到大量的能量每平方米比热带地区。4月初,北极是阳光一天24小时,但大部分*不*阳光(在能源/ m <一口> 2 < /一口>等)比赤道进入12。) Another big consideration is [atmospheric circulation][1]. Earth's atmosphere circulates in six main cells (three above the equator, three below). Within each of these cells, air near ground level moves toward the equator, being warmed by sunlight and by the ground/sea along its way, and insulated from space by the atmosphere above it. At the edge of the cell, it's warmed enough that it rises high up and circulates back towards the poles, losing heat to space before it reaches the polar end of its cell and descends again, bringing cool air back to the surface. The net effect of this is to further cool the polar end of things and warm the equatorial end of things [1]: https://en.wikipedia.org/wiki/Atmospheric_circulation