Measurements by Reynolds et al. (1975) show that direct absorption of solar radiation in clouds is an important tropospheric heat source. Their observations show cloud absorptance values as high as 30–52%. For a particular case study the measurements of Reynolds et al. showed an absorptance value of 36% while calculations in Chapter 2 showed a corresponding absorptance value of 17%, i.e., less than half. Twomey (1976) has shown that theory predicts a maximum absorptance value of 20%. Moreover, Twomey (1972) showed that the addition of particulates does not add significantly to cloud absorption. Therefore, there has been a disparity between theory and observations. Twomey (1976) mentioned that in order to obtain such large absorptance values as measured by Reynolds et al. there must either be total absorption of solar radiation at wavelengths > 0.7 µm or significant absorption of solar radiation at wavelengths < 0.7 µm. However, there has been no apparent mechanism postulated to satisfy either of these two conditions until now.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- The Effect of Cloud Bimodal Drop Size Distributions upon the Radiative Characteristics of Clouds
Ronald M. Welch
Stephen K. Cox
- American Meteorological Society
- Chapter 3
Systemische Notwendigkeit zur Weiterentwicklung von Hybridnetzen