noyau hygroscopique

CONT: The exact form taken by hygroscopic nuclei is most frequently that of droplets of solution. It was established by Lord Kelvin that the vapour pressure over the surface of a water drop in equilibrium with its surroundings is greater than that over a plane water surface. ... The vapour pressure over the surface of a solution is always less than that over pure water at the same temperature. For this reason, a solution is hygroscopic, and absorbs water vapour from the surrounding air, becoming diluted in the process. From this it follows that nuclei in the form of droplets of solution may be expected to be satisfactory condensation kerns. When particles of hygroscopic substances are exposed to sufficiently damp air, they become droplets of solution.