A far-wing line shape theory based on the binary collision and quasistatic approximations that is applicable for both the low- and high-frequency wings of the vibration-rotational bands has been developed. This theory has been applied in order to calculate the frequency and temperature dependence of the continuous absorption coefficient for frequencies up to 10,000 cm−1 for pure H2O and for H2O-N2 mixtures. The calculations were made assuming an interaction potential consisting of an isotropic Lennard-Jones part with two parameters that are consistent with values obtained from other data, and the leading long-range anisotropic part, together with the measured line strengths and transition frequencies. The results, obtained without the introduction of adjustable parameters, compare well with the existing laboratory data, both in magnitude and in temperature dependence. This leads us to the conclusion that the water continuum can be explained in terms of far-wing absorption. Current work in progress to extend the theory and to validate the theoretically calculated continuum will be discussed briefly
Attention is given to all processes extending from the earth surface to the tropopause, but special emphasis continues to be devoted to the physics of clouds and precipitation, i.e. atmospheric aerosols; microphysical processes; cloud dynamics and thermodynamics; numerical simulation of cloud processes; clouds and radiation; meso- and macrostructure of clouds and cloud systems, and weather modification.
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Water continuum CO2 laser absorption spectra are reported for temperatures between 27 and -10°C. The continuum is found to possess a negative temperature coefficient. The results obtained suggest that the magnitude of this temperature coefficient increases with increasing water pressure and decreasing temperature. The temperature coefficients between 27 and 10°C for air mixtures containing 3.0- and 7.5-Torr water vapor are -2.0 ± 0.4 and -2.9 d 0.5%/ C, respectively. For mixtures with 3.0-Torr water the 10-O°C temperature coefficient is -7.7 ± 0.2%/°C. The temperature and water pressure dependencies observed for the continuum suggest that while both collisional broadening and water dimer mechanisms contribute to the continuum, the dimer mechanism is more important over this temperature range.
