Final answer:
Passive cooling relies on the natural principle of convection, where cool air rises and warm air sinks. This principle is utilized in natural convection heating systems to transfer heat throughout a room.
Step-by-step explanation:
Passive cooling relies on the natural principle of convection. Convection is the process in which heat is transferred through a fluid by the movement of the fluid itself. In the case of passive cooling, cool air rises due to buoyancy, while warm air sinks. This phenomenon occurs because cool air is denser than warm air, causing the cool air to displace the warm air and rise.
For example, in a room, if you open a window on the lower level and another window on the upper level, the cool air from the lower level will enter the room, while the warm air inside will rise and exit through the upper window.
This principle is utilized in natural convection heating systems, such as a gravity furnace, where air is heated and then rises, creating a convective loop that transfers heat to other parts of the room.