Radiant heat is characterized as:

Radiant heat is characterized as a wave form of heat transfer, which is correct because it primarily involves the transfer of energy through electromagnetic waves. This form of heat transfer does not require a medium, such as air or liquid, to propagate. Instead, it can travel through the vacuum of space, as demonstrated by the sun's rays reaching the Earth.

In radiant heat transfer, energy is emitted as infrared radiation and can be absorbed by surfaces that are capable of thermal radiation absorption, leading to an increase in temperature. This is distinct from other heat transfer methods, such as conduction, which requires direct contact between materials, or convection, which involves the movement of fluids. The understanding of radiant heat is vital for applications like heating systems and energy efficiency in buildings, where controlling radiant heat can impact overall thermal comfort.