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Natural convection can occur when there are hot and cold regions of either air or water, because both water and air become less dense as they are heated. But, for example, in the world's oceans it also occurs due to salt water being heavier than fresh water, so a layer of salt water on top of a layer of fresher water will also cause convection.
As a consequence, the fluid is displaced while the cooler fluid gets denser and the fluid sinks. Thus, the hotter volume transfers heat towards the cooler volume of that fluid. [2] Familiar examples are the upward flow of air due to a fire or hot object and the circulation of water in a pot that is heated from below.
The energy needed to evaporate the water is taken from the air in the form of sensible heat and converted into latent heat, while the air remains at a constant enthalpy. Latent heat describes the amount of heat that is needed to evaporate the liquid; this heat comes from the liquid itself and the surrounding gas and surfaces.
The characteristic energy k B T associated with a single microscopic degree of freedom, where T denotes temperature and k B denotes the Boltzmann constant. Mark Zemansky (1970) has argued that the term “thermal energy” is best avoided due to its ambiguity.
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. [1] Thermals are created by the uneven heating of Earth's surface from solar radiation , and are an example of convection , specifically atmospheric convection .
g is the acceleration due to gravity ν is the kinematic viscosity α is the thermal diffusivity β is the thermal expansion coefficient. As the Rayleigh number increases, the gravitational forces become more dominant. At a critical Rayleigh number of 1708, [5] instability sets in and convection cells appear.
Primordial heat is the heat lost by the Earth as it continues to cool from its original formation, and this is in contrast to its still actively-produced radiogenic heat. The Earth core's heat flow—heat leaving the core and flowing into the overlying mantle—is thought to be due to primordial heat, and is estimated at 5–15 TW. [23]
Reynolds Experiment (1883). Osborne Reynolds standing beside his apparatus. In 1883, scientist Osborne Reynolds conducted a fluid dynamics experiment involving water and dye, where he adjusted the velocities of the fluids and observed the transition from laminar to turbulent flow, characterized by the formation of eddies and vortices. [5]