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