6) (5p) an ice crystal in form of a thin hexagonal plate grows by diffusion in an environment saturated with respect to water at a temperature of -4°c and a pressure of 80 kpa. a) determine the time required for it to grow to a diameter of 1 mm, starting from a mass of 10-s kg. take the geometry factor to be that of a circular disk. assume that mass and diameter of the plate are related by m = 1.9 × 10-2 , with mass in gram and d in cm. neglect ventilation effects. (2p) b) if diameter and fall speed are related by u = c* d (with c = 520 s-1), determine the distance the crystal falls during the growth to 1 mm diameter. (2p) c) why is knowledge of the mass-size relation so important in cloud microphysics? (1p)