Morphological structure of an interstellar ice. Top panels: accretion rate during the molecular cloud collapse. Bottom panels: fractional ice composition AN as a function of the ice thickness (in ML). Left-hand side column: fast flow. Right-hand side column: slow flow. Black indicates H₂O, orange represents NH₃, and blue symbolizes CO. Red lines are for the cloud thermal profile. Dashed lines in the bottom panels represent the case in which gas and dust temperatures differ (T_g – T_d = 50 K).