Regions of the Electromagnetic Spectrum

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100 m

1.0 m

Television Waves

(VHF and UHF)

1.0 m

Radio Waves

100 m

Figure 2-9. Electromagnetic spectrum on a

vertical scale.

h. Regions of the Electromagnetic Spectrum. Different regions of the electromagnetic

spectrum can provide discrete information about an object. The categories of the electro-

magnetic spectrum represent groups of measured electromagnetic radiation with similar

wavelength and frequency. Remote sensors are engineered to detect specific spectrum

wavelength and frequency ranges. Most sensors operate in the visible, infrared, and mi-

crowave regions of the spectrum. The following paragraphs discuss the electromagnetic

spectrum regions and their general characteristics and potential use (also see Appendix

B). The spectrum regions are discussed in order of increasing wavelength and decreasing

frequency.

(1) Ultraviolet. The ultraviolet (UV) portion of the spectrum contains radiation

just beyond the violet portion of the visible wavelengths. Radiation in this range has

short wavelengths (0.300 to 0.446 m) and high frequency. UV wavelengths are used in

geologic and atmospheric science applications. Materials, such as rocks and minerals,

fluoresce or emit visible light in the presence of UV radiation. The florescence associated

with natural hydrocarbon seeps is useful in monitoring oil fields at sea. In the upper at-

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