Daytime temperatures may reach above freezing, but because the planet is blanketed by the mere wisp of an atmosphere,the heat radiates back into space. 白天,那里的温度可以达到零上,但因为包裹火星的大气层极为稀薄,热量又会辐射回宇宙中。
This afternoon's sunshine could nudge the temperature above freezing. 今天下午的阳光可使温度达到冰点以上。
On a cloudless night, frost may form on horizontal surfaces even when the temperature of the air is above freezing. 在晴朗的夜晚,即使空气的温度在冰点以上,地平面上也能结霜。