Req lm

Figure 9. Modified Köhler curves and the hysteresis cycle. The blue curves are the modified Köhler curves; the green curves are the traditional Köhler curves, except below the spontaneous dehydration point, SSpon; the upper dotted line indicates the Kelvin effect, and the lower dotted line connects the deliquescence part of each curve, the end of which is the common or "bulk" deliquescence point, Sdeliq,b. The thin solid line shows the growth path of dry aerosols (from point D) in moisturizing air; it acquires water only when the humidity reaches the deliquescence point, Sdeliq. The thin dashed lines show the growth path of a wet aerosol (from point W) in drying air; it will suddenly lose all the water at the dehydration point, Sdehyd, if under thermodynamic equilibrium, at SSp0n if the salt core appears by homogeneous nucleation, or somewhere in between if the salt core appears by heterogeneous nucleation. (See Chen, 1994, for details.)

100% relative humidity with respect to water such that the aerosols may activate into cloud drops. Only then can the strong uptake of water by the cloud drop dilute the solute effect to allow droplets to freeze. However, if the air is cold enough (significantly lower than —40°C) to overcome the suppression of the freezing point, the haze particles themselves can directly freeze to form ice. Note that these processes are time-dependent and self-limiting, as the ice crystals already formed will grow and deplete

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