Clive M. Countryman

“ The Nature of Heat Three ingredients are essential for a wildland fire to start and to burn. First, there must be burnable fuel available. Then enough heat must be applied to the fuel to raise its temperature to the ignition point. And finally, there must be enough air to supply oxygen needed to keep the combustion process going and thus maintain the heat supply for ignition of unburned fuel. These three indispensable ingredients—fuel, heat, and oxygen—make up the fire triangle. All must be present if there is to be fire. ”

“ For example, radiant energy from the sun is transformed by the process of photosynthesis to stored chemical energy in vegetation. When the vegetation is burned, the chemical energy is transformed to thermal energy, radiant energy, and the kinetic energy in the rising air in the convection column over the fire. The kinetic energy in falling water can be used to generate electrical energy, which in turn can be changed back to thermal and radiant energy by an electric heater, or to kinetic energy again through the use of an electric motor. ”

“ The science of heat is relatively new Everyone knows how heat feels, and is well aware of its many applications in daily life. Heat from the sun is the basic control of our weather, and this heat is also essential in the growing of food crops and other vegetation. Without the sun's heat, life could not exist on the earth. ”

“ Through the science of thermodynamics, heat has a place in many of the industrial processes that bring us the conveniences of modern life. But as recently as 200 years ago, the true nature of heat was not understood. In the early days of science the phenomena associated with heat were ascribed to a mystical and intangible fluid called "caloric." This fluid was believed to have the power of penetrating and expanding materials, sometimes melting or dissolving them, and converting some substances to vapor. ”

“ Under similar conditions, the heat capacity of dry soil and rock is 19 to 20 Btu/ft3/°F, and that of water is about 62 Btu/ ft3/°F. The high heat capacity of water is one of the reasons why the climate near oceans and large lakes is often more moderate than that of the climate further inland. The water absorbs and stores large quantities of heat during the summer without much change in temperature, and this tends to keep the air over the adjacent land relatively cool. In the winter the stored heat is released and warms the air over nearby land areas. ”

“ The caloric fluid was considered intangible, since even the most careful experiments in adding or subtracting heat by nondestructive heating or cooling of a substance failed to produce any changes in its weight.
Heat is energy We know now that heat is not a fluid, nor a substance at all, but is really one of the several forms of energy. ”

“ As warm outside air flows through water soaked excelsior pads, some of the water vaporizes, and much of the heat needed for this vaporization is drawn from the incoming air, thus cooling it. Cooling towers used to cool water in industrial processes operate in much the same way. ”