frequently Convection: Movement in Fluids In the form of heat transfer called convection, heat is transferred by the movement of molecules in a fluid from a warm region to a cooler one The fluid may be a liquid such as water, or it may be the air or other gases Convection is a process that combines conduction and mixing: energetic molecules move from one point in space to another, and then collide with slower particles Convection is an influential phenomenon, contributing as it does to winds, storms, ocean currents, the heating of our homes, and the boiling of water on the stove It occurs because air and water take up more space — become less dense — when their molecules absorb energy and move faster, and so they rise when they heat up and sink again as they cool off Radiation: the Pure Energy Of radiant Heat and Radiation: the Pure Energy Of radiant Heat and Microwaves We all know that the earth is warmed by the sun How does solar energy reach us across millions of miles of nearly empty space, where there’s nothing there to conduct or convect? The answer is thermal radiation, a process that does not require direct physical contact between heat source and object All matter emits thermal radiation all the time, though normally we can detect it only when something is very hot The warmth we feel from sunlight or a stove burner comes from thermal radiation It’s emitted by atoms and molecules which, having absorbed energy, release it again not in the form of faster movement, but as waves of pure energy Radiant Heat Is Invisible “Infrared” Radiation As unlikely as it may seem, radiated heat is close kin to radio waves, microwaves, visible light, and X rays Each of ... where there’s nothing there to conduct or convect? The answer is thermal radiation, a process that does not require direct physical contact between heat source and object All matter emits thermal radiation all the time,...Radiation: the Pure Energy Of radiant Heat and Microwaves We all know that the earth is warmed by the sun How does solar energy reach us across millions of miles of nearly empty space, where there’s nothing there to conduct or... though normally we can detect it only when something is very hot The warmth we feel from sunlight or a stove burner comes from thermal radiation It’s emitted by atoms and molecules which, having absorbed energy,