This energy is in the form of electromagnetic radiation. All electromagnetic radiation has fundamental properties and behaves in predictable ways according to the basics of wave theory. Two characteristics of electromagnetic radiation are particularly important for understanding remote sensing. These are the wavelength and frequency . The wavelength is the length of one wave cycle, which can be measured as the distance between successive wave crests.
Frequency refers to the number of cycles of a wave passing a fixed point per unit of time.
The shorter the wavelength, the higher the frequency. The longer the wavelength, the lower the frequency. Understanding the characteristics of electromagnetic radiation in terms of their wavelength and frequency is crucial to understanding the information to be extracted from remote sensing data. Next we will be examining the way in which we categorize electromagnetic radiation for just that purpose.