Science. 1989 Jan 6;243(4887):57-63. doi: 10.1126/science.243.4887.57.
The study of climate and climate change is hindered by a lack of information on the effect of clouds on the radiation balance of the earth, referred to as the cloud-radiative forcing. Quantitative estimates of the global distributions of cloud-radiative forcing have been obtained from the spaceborne Earth Radiation Budget Experiment (ERBE) launched in 1984. For the April 1985 period, the global shortwave cloud forcing [-44.5 watts per square meter (W/m(2))] due to the enhancement of planetary albedo, exceeded in magnitude the longwave cloud forcing (31.3 W/m(2)) resulting from the greenhouse effect of clouds. Thus, clouds had a net cooling effect on the earth. This cooling effect is large over the mid-and high-latitude oceans, with values reaching -100 W/m(2). The monthly averaged longwave cloud forcing reached maximum values of 50 to 100 W/m(2) over the convectively disturbed regions of the tropics. However, this heating effect is nearly canceled by a correspondingly large negative shortwave cloud forcing, which indicates the delicately balanced state of the tropics. The size of the observed net cloud forcing is about four times as large as the expected value of radiative forcing from a doubling of CO(2). The shortwave and longwave components of cloud forcing are about ten times as large as those for a CO(2) doubling. Hence, small changes in the cloud-radiative forcing fields can play a significant role as a climate feedback mechanism. For example, during past glaciations a migration toward the equator of the field of strong, negative cloud-radiative forcing, in response to a similar migration of cooler waters, could have significantly amplified oceanic cooling and continental glaciation.
气候和气候变化的研究受到缺乏有关云对地球辐射平衡影响的信息的阻碍，这种影响被称为云辐射强迫。从 1984 年发射的地球辐射收支实验（ERBE）卫星上获得了全球云辐射强迫分布的定量估计。对于 1985 年 4 月，由于行星反照率增强而导致的全球短波云强迫（-44.5 瓦/平方米（W/m(2)））在幅度上超过了由于云的温室效应而导致的长波云强迫（31.3 W/m(2)）。因此，云对地球具有净冷却效应。这种冷却效应在中高纬度海洋上空很大，达到-100 W/m(2)。每月平均长波云强迫在热带对流扰动地区达到 50 到 100 W/m(2)的最大值。然而，这种加热效应几乎被相应的大的负短波云强迫抵消，这表明热带地区处于微妙的平衡状态。观测到的净云强迫的大小大约是 CO(2)倍增辐射强迫预期值的四倍。云强迫的短波和长波分量大约是 CO(2)倍增的十倍。因此，云辐射强迫场的微小变化可以作为气候反馈机制发挥重要作用。例如，在过去的冰川时期，强烈的、负的云辐射强迫场向赤道的迁移，以响应较冷海水的类似迁移，可能会显著放大海洋冷却和大陆冰川作用。
