The above equation can also be utilized to calculate conduction loss from a human body to ambient air. For example, for a 1.5 tall man wearing dry, insulating clothing, the rate of conductive heat loss on a cold day (ambient temperature at 0oC, normal skin temperature at 37oC) can be calculated as 178W. For the same person wearing wet clothing, however, the equivalent rate is 2,565W. This significant difference in heat losses explains the onset of hypothermia when someone is exposed to ice-cold water or rain (Forinash, 2010). Conduction takes place on a microscopic level as particles of kinetic energy are transferred between two different systems (Abbott, et al., 2005). When atoms and/or molecules heat up, vibrate, or move rapidly, some of their energy gets transferred to other atoms and molecules that are in close proximity. In other words, heat is transferred to the surrounding particles and away from the vibrating particles. Solid objects that are engaged in thermal conduct use conduction as a significant means for heat transfer (Abbott, et al., 2005; Geankoplis, 2003). The vibration is what creates the heat, and the heat is then distributed from one atom or molecule to the other (or others). That...
This change in heat will depend on the size of the systems where the atoms or molecules are located, but will also be affected by the rate of vibration and other factors that can account for how quickly (or slowly) the change in heat takes place. The heat loss or gain may be noticeable over time on a level beyond what is seen molecularly, but the heat transfer does not originate at a larger or more detectable level. The molecules and atoms are the beginning of the heat transfer, which expands from that point.
Convection: In contrast to conduction, which is an atomic or molecular phenomenon, conduction is a bulk phenomenon, where transfer occurs due to mass transport in fluids. Since mass transfer cannot take place in a solid, this mode of heat transfer is restricted to solid/fluid interfaces. In case of a temperature differential between a solid or liquid placed in the atmosphere, two types of convections can occur -- natural convection and forced convection. In the former, the thermal gradient induces a density gradient, so that the hotter, less dense layers are
