Earth’s temperature begins with the Sun. Roughly 30 percent of incoming sunlight is reflected back into space by bright surfaces like clouds and ice. Of the remaining 70 percent, most is absorbed by the land and ocean, and the rest is absorbed by the atmosphere. The absorbed solar energy heats our planet.

　　 地球的温度开始太阳。大约百分之30的太阳光被反射回太空的光明面与云冰。在余下的百分之70，多数是由陆地和海洋吸收，其余的被大气层吸收。吸收太阳能加热我们的星球。

　　 As the rocks, the air, and the seas warm, they radiate “heat” energy (thermal infrared radiation). From the surface, this energy travels into the atmosphere where much of it is absorbed by water vapor and long-lived greenhouse gases such as carbon dioxide and methane.

　　 当岩石，空气，和温暖的海洋，他们辐射热能源(热辐射)。从表面上看，这种能量进入大气层，大部分是由水蒸气和长寿命的温室气体如二氧化碳和甲烷的吸收。

　　 When they absorb the energy radiating from Earth’s surface, microscopic water or greenhouse gas molecules turn into tiny heaters— like the bricks in a fireplace, they radiate heat even after the fire goes out. They radiate in all directions. The energy that radiates back toward Earth heats both the lower atmosphere and the surface, enhancing the heating they get from direct sunlight.

　　 当他们吸收辐射能量从地球表面，微观水或温室气体分子变成小加热器-就像在壁炉的砖，他们散发热量，即使在火熄灭。他们在所有方向辐射。能量辐射回地球加热低层大气和表面，增强他们从阳光直射加热。

　　 This absorption and radiation of heat by the atmosphere—the natural greenhouse effect—is beneficial for life on Earth. If there were no greenhouse effect, the Earth’s average surface temperature would be a very chilly -18°C (0°F) instead of the comfortable 15°C (59°F) that it is today.

　　 这种吸收和辐射热的气氛自然温室效应有利于地球上的生命。如果没有温室效应，地球表面的平均温度将是一个非常寒冷的18°C(0°F)而不是舒适的15°C(59°F)，它是今天。