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Physiology: Newborns lack the ability of thermogenesis due to underdeveloped shivering mechanism. Body heat is lost through conduction, convection, and radiant heat. [1] Thermoregulation is achieved through several methods: the metabolism of brown fat and Kangaroo care, also known as skin to skin.
There are four avenues of heat loss: convection, conduction, radiation, and evaporation. If skin temperature is greater than that of the surroundings, the body can lose heat by radiation and conduction. But, if the temperature of the surroundings is greater than that of the skin, the body actually gains heat by radiation and conduction. In such ...
Convection-cooling is sometimes loosely assumed to be described by Newton's law of cooling. [6] Newton's law states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings while under the effects of a breeze. The constant of proportionality is the heat transfer coefficient. [7]
A correction to Newton's law concerning convection for larger temperature differentials by including an exponent, was made in 1817 by Dulong and Petit. [6] (These men are better-known for their formulation of the Dulong–Petit law concerning the molar specific heat capacity of a crystal.)
Convective heat transfer, or simply, convection, is the transfer of heat from one place to another by the movement of fluids, a process that is essentially the transfer of heat via mass transfer. The bulk motion of fluid enhances heat transfer in many physical situations, such as between a solid surface and the fluid. [10]
Studies have shown that the warmth from the fires they build is enough to keep the body from fighting heat loss through shivering. [18] Inuit use well-insulated houses that are designed to transfer heat from an energy source to the living area, which means that the average indoor temperature for coastal Inuit is 10 to 20 °C (50 to 68 °F).
Human heat-loss mechanisms are limited primarily to sweating (which dissipates heat by evaporation, assuming sufficiently low humidity) and vasodilation of skin vessels (which dissipates heat by convection proportional to the temperature difference between the body and its surroundings, according to Newton's law of cooling).
The term radiative cooling is generally used for local processes, though the same principles apply to cooling over geological time, which was first used by Kelvin to estimate the age of the Earth (although his estimate ignored the substantial heat released by radioisotope decay, not known at the time, and the effects of convection in the mantle).