sentences: the bottom of snow exerts top slip on balloon on it
docs: snow is frozen_water_falling_from_sky. falling_backwards is falling. falling_forward is falling. mountains has snow_on_top snowboarding is slide. stand_underneath_when is raining_or_snowing. snow_skiing is sliding_low_friction. falling_freefall is falling. rock_bottom is bottom. snowboard_trick is snowboarding.