Introductory remarks

Abstract

The study of the radiative balance in the atmosphere is very complex and difficult. The factors which determine the equilibrium are known in general terms, but the problem of developing a detailed understanding, particularly if the aim is to assist meteorological prediction, is another matter. Only part of the incoming solar radiation reaches ground level without being affected by the atmosphere; the remainder is either reflected back into space or absorbed or scattered by the atmosphere. The incident radiant energy absorbed in this way is degraded to longer wavelengths and is radiated from the atmosphere as infra-red radiation. Part of this reaches the surface and is absorbed there, while the remainder is re-radiated to outer space. Some heat also reaches the surface from the atmosphere by eddy-current transport. Again, energy leaves the surface in the form of infra-red radiation. Most of this is absorbed by the water vapour in the atmosphere, except in the wavelength region 8 to 13 μ . Radiation in this wave­length ‘window’ passes right through the atmosphere to outer space. Heat is also carried to the atmosphere from the surface by evaporation, condensation and precipitation phenomena.