Fig. 11. Fraction of transmitted laser power absorbed or scattered by each atmospheric layer (Midlatitude Winter Model). promote vertical mixing and waste-heat dispersal more effectively than man-made edifices such as cooling towers. Unlike many cooling towers, which rely upon evaporative cooling, atmospheric disposal of that portion of the plant’s waste heat due to laser-beam absorption will not induce cloud generation. Laser hole boring at X — 5, 9, and 11 ^m through certain types of haze, fogs, and clouds may be possible consistent with safety and environmental concerns and without the need for weapon-quality laser beams (21). In particular, all but the thickest cirriform and middle clouds and all stratiform clouds with the exception of nimbostratus can be penetrated with power densities of 100-200 W/cm2. Cumuliform clouds and most mixed types found during overcast conditions, which occur with greater frequency, require substantially higher power densities for penetration (>1 kW/cm2). Hole boring under these meteorological conditions is unacceptable given the present safety considerations. Furthermore, since most cloud types in the troposphere and stratosphere will renucleate after passing through the beam, the prospect for changing the continental cloud distribution or albedo is highly improbable. Aerosol Effects. As shown in Figures 10 and 11, aerosols are the primary absorbers in the stratosphere (aerosol absorption and scattering coefficients are about equal at X = 5 pan). Because the Junge sulfate layer is important to the heat balance in the lower stratosphere and because of the long residence time of stratospheric aerosols (54,55), the possibility of laser-induced depletion of this layer must be considered. Two processes for decomposition of sulfate aerosols by laser irradiation are possible for power densities —10 W/cm2. First, absorption of IR radiation is known to prefer-
RkJQdWJsaXNoZXIy MTU5NjU0Mg==