Latent Heat Released Experimentally by Adding Sodium Chloride Particles to the Atmosphere

Abstract

Dry particles of sodium chloride, in the size range of 0.5 to 20 ? in diameter, were introduced from an aircraft into moist air at altitudes of 400?500 m over the sea near the island of Hawaii. Discharge rates from each 400-kg load were adjusted to try to produce salt concentrations in the air of 40 mg kg?1, with the purpose of releasing the latent heat in about 107 kg of air as a result of the condensation of water vapor on the salt. Forty-one separate experiments in air with a relative humidity of 80?90 per cent showed that the salt-laden air was warmer than the ambient air by 0.35C on the average. It is suggested that air, heated internally in this manner, may under certain conditions rise to the lifting condensation level, and that this process may be utilized in studies of convective cloud-initiating processes. On the modest scale of operation conducted here, each experiment, involving two light aircraft, cost about $250.