Heat transfer
Heat transfer is the way the heat moves from one physical system (or body) to another. Heat transfer requires a difference in temperature.[1] Heat moves from the hotter body (higher temperature) to the colder one (lower temperature).[2] The bodies in question may be in a solid state, a liquid state or a gaseous state.[2] There are three modes of heat transfer: conduction, convection and radiation.[1]
Heat Transfer Media
Simulation of thermal convection in the Earth's mantle. Colors span from red and green to blue with decreasing temperatures. A hot, less-dense lower boundary layer sends plumes of hot material upwards, and cold material from the top moves downwards.
Earth's longwave thermal radiation intensity, from clouds, atmosphere and surface.
The four fundamental modes of heat transfer illustrated with a campfire
Red-hot iron object, transferring heat to the surrounding environment through thermal radiation
Lightning is a highly visible form of energy transfer and is an example of plasma present at Earth's surface. Typically, lightning discharges 30,000 amperes at up to 100 million volts, and emits light, radio waves, X-rays and even gamma rays. Plasma temperatures in lightning can approach 28,000 kelvins (27,726.85 °C) (49,940.33 °F) and electron densities may exceed 1024 m−3.
Nucleate boiling of water.
A time-lapse animation of icecubes melting in a glass (50 minutes).
Heat exposure as part of a fire test for firestop products
Schematic flow of energy in a heat engine.
