When a hot pan is removed from the fire or heat source, it slowly cools down due to the process of heat transfer. Heat always flows from a region of higher temperature to a region of lower temperature until both regions reach thermal equilibrium, where their temperatures are equal.
There are three main modes of heat transfer that contribute to the cooling of a hot pan:
Conduction: This is the transfer of heat within an object or between objects that are in direct contact. When the pan is on the heat source, the bottom of the pan is in contact with the hot stove, and heat is conducted from the stove to the pan, making the pan's bottom hot. When the pan is removed from the heat source, the hot bottom of the pan continues to conduct heat to cooler parts of the pan, including the sides and the handle.
Convection: Convection is the transfer of heat through the movement of fluids or gases. When the pan is on the heat source, the air around it gets heated, and this hot air rises while cooler air moves in to take its place. When the pan is removed from the heat source, convection continues as the hot air around the pan transfers some heat away from it.
Radiation: Radiation is the transfer of heat in the form of electromagnetic waves, like infrared radiation. When the pan is heated, it emits infrared radiation, which is absorbed by nearby cooler surfaces, causing them to warm up. When the pan is removed from the heat source, it continues to emit radiation, but at a decreasing rate, which contributes to the cooling process.
Together, these three modes of heat transfer work to reduce the temperature of the hot pan until it reaches the ambient temperature of its surroundings. The rate at which the pan cools down depends on various factors, including the material and thickness of the pan, the initial temperature difference, and the surrounding environment's temperature.