  There exists the threshold-sensitive dynamical transition between the uniform
and the periodic growth modes in the domain growth of ascorbic acid crystals
from its aqueous supersaturated solution film. The crystal growth induces the
solution flow. Humidity controls the fluidity of the solution. The solution
flow varies the film thickness. The threshold exists in the thickness of the
solution film, and the crystal growth almost stops if the thickness becomes
lower than the threshold.
