premise: As we were dragging the suitcases , snow was piling up in front of them so they were just getting heavier and heavier and heavier . Plus , our glasses were getting all fogged up , and it was cold and snowing ( it started again as we were leaving her apartment , and stopped pretty much as soon as she left ) . Anyway , we finally made it there . What may be the reason for the suitcases getting heavier ?
hypothesis: Fog was making them heavier .