Energy propagated in the form of an advancing electric and magnetic field disturbance. The term radiation, alone, is commonly used for this type of energy, although it actually has a broader meaning. In the classical wave theory of light (or electromagnetic theory) the propagation is thought of as a continuous wavelike disturbance of the electric and magnetic fields, which oscillate in planes orthogonal to each other and to the direction of propagation. The quantum theory of electromagnetic radiation adds the perspective that these disturbances also have particle-like attributes, being quantized into photons of minimum energy that have finite momentum. The observable properties and physical effects of various portions of the electromagnetic spectrum are of considerable importance in meteorology and are discussed under their respective names. See cosmic rays, gamma rays, x-rays, ultraviolet radiation, visible radiation, infrared radiation, microwave radiation, radio waves.