Natural convection through evaporator coils is caused by:

Natural convection through evaporator coils is primarily driven by differences in fluid density, which occur due to changes in temperature. As the evaporator coils cool the air passing over them, the temperature of the air decreases, leading to an increase in its density. Denser air tends to sink, while warmer, less dense air rises. This process creates a natural flow of air - cold air descends and warmer air ascends - allowing ventilation around the coils without the need for mechanical assistance.

In this context, the concept of natural convection is crucial to understanding how heat transfer occurs in refrigeration systems. The movement of air created by these density differences enhances the efficiency of heat exchange in the evaporator, ultimately contributing to the cooling effect in the conditioned space.