这是典型的Trenberth能源预算图所示的地球:[![在这里输入图像描述][1]][1]86.4美元\ mathrm{\压裂{W} {\, m ^ 2}} $是能量运动到大气中。340.3美元\ mathrm{\压裂{W} {\, m ^ 2}} $是整个温室效应。很重的大多数自然温室效应(水蒸气)[2]。水循环表明平均水汽在大气中停留两周([文章][3]现在显示8 - 9天)。这是一个估计,大约需要2 - 4天平均水分子能量绕道回到地球,因为它从表面转移到大气的吸收,最终凝结/沉积。我可以想象你的朋友可能不会感到舒服只有使用这个数字来考虑估计,也许可以尝试另一种方式的隧穿到这个想法....稳定大气中水汽含量,最后唯一的主要方式,从表面大气水分传输能量是由其合成沉淀(其他水转换没有净变化对水分和不净能量从地上转移…水蒸发然后再浓缩在地面没有净能量变化,同样水蒸气变成了云,然后在这一水平没有reevaporates净能量变化过程)。地球的每日平均降水(单位面积约2毫米)[4]。 The energy for evaporation is [2256 kJ/kg water][5]. So for a square meter, that's $$0.2 \frac{\,\mathrm{cm}}{\,\mathrm{day}} \cdot 1\,\mathrm{m^2} \cdot \left(\frac{1\,\mathrm{g}}{\,\mathrm{cm^3}}\right) \cdot 2256 \frac{\mathrm{J}}{\mathrm{g}} \cdot \left(\frac{100\,\mathrm{cm}}{1\,\mathrm{m}}\right)^2 = 45120 \frac{\mathrm{J}}{\mathrm{m^2}}\;\mathrm{per}\;\mathrm{day}$$ Which, converting to per second to get in Watts, that's about $.5\mathrm{\frac{W}{\,m^2}}$, on the same scale as the figure indicates. How long does it take to achieve that in greenhouse reradiation by that particular water vapor? In a sense it's not easy to calculate the energy directly by each molecule... we know the radiative properties of water, what [wavelengths water reflects/absorbs/radiates more at][6], but it's a cumulative distribution, each molecule adding a bit to the overall absorption. To work it out from radiative result, you can again go back to that resident time and compare that to how much energy increase the greenhouse residency effect contributes to the atmosphere (which is basically [roughly half the energy we receive in a day at the surface is energy from previous surface radiation being returned back][7]... or works out to be that $340.3\mathrm{\frac{W}{\,m^2}}$ of greenhouse return). it all leads back to that same ratio that was given from the figure, 86.4/340.3, and so the same residency time. It may really help to think of it not so much as how long it stays and how much that water molecule contributes while it is in the atmosphere, but instead about the whole water cycle process being what *maintains* the amount of water vapor in the atmosphere to allow for that amount of continued greenhouse return, and so it's just one continuous amount versus the other. But if you really do want to think of it as the time for water vapor to generate its greenhouse effect matching its latent heat transfer, it must be **on the order of about 3 days**, or around a quarter of its time in the atmosphere, to get the energy amounts we see. [1]: https://i.stack.imgur.com/XSsWy.jpg [2]: https://skepticalscience.com/water-vapor-greenhouse-gas.htm [3]: https://hess.copernicus.org/articles/21/779/2017/hess-21-779-2017.html#:~:text=Based%20on%20state-of-the-art%20data%2C%20we,atmosphere%20of%208%E2%80%9310%20days [4]: https://www.smithsonianmag.com/arts-culture/what-is-the-daily-rainfall-on-earth-and-more-questions-from-our-readers-37945925/ [5]: https://www.engineeringtoolbox.com/fluids-evaporation-latent-heat-d_147.html [6]: https://en.wikipedia.org/wiki/Water_vapor_windows [7]: https://atmos.washington.edu/academics/classes/2001Q4/211/notes_greenhouse.html