Complexes of atmospheric molecules and atoms with water, H2O.X, where X is H2O, N-2, O-2, Ar, and CO2, are investigated to evaluate their possible role in the absorption of solar energy and consequently in influencing the Earth's climate. The atmospheric abundance and absorption spectra of these complexes are calculated and used in a line-by-line radiative transfer model to assess their contribution. We have used statistical mechanics to calculate equilibrium constants and the harmonically coupled anharmonic oscillator local mode model to calculate fundamental and overtone OH-stretching vibrational band frequencies and intensities. Parameters for these calculations were obtained with the use of ab initio methods. Apart from the water dimer, no OH-stretching bands are significantly frequency shifted compared to those in the water monomer, implying that observation of the vibrational spectra of these hydrates in the atmosphere will be difficult. Of the studied complexes, we find that the O-2 and N-2 monohydrates are likely to contribute the most to absorption of solar radiation; however, the absolute absorption is highly dependent on the band shape of the vibrational transitions.