This freezer compartment is similar to a normal cave. When the door is opened the cold air spills out and is replaced by warmer air. Of course there is no door on a cave, so as air inside cools, it freely flows out and is replaced by warmer air. |
This is an example of heat transfer by "convection", which is the transfer of heat by the movement of fluids (such as air and water) due to density differences. In normal caves (and the freezer shown here), warm air moving in to replace the heavier cold air that has spilled out causes the normal cave to be too warm for water stay frozen year-round.
Earth Science Teacher at Helena High School