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Electromagnetic Spectrum

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Electromagnetic Spectrum EMR is a form of energy exhibiting wave-like behaviour as it travels through space. EMR ranges from very high energy radiation such as gamma rays and X rays through ultraviolet light, visible light, infrared radiation and microwaves to radio waves.  The range of frequencies of EMR is known as the electromagnetic spectrum. The Sun produces a continuous spectrum of energy from gamma rays to radio waves that continually bathe the Earth in energy. The visible portion of the spectrum may be measured using wavelength (measured in mm or nm) or electron volts (eV) - All units are interchangeable. Classification of Electromagnetic Radiation Infrared radiation (750 nm - 1 mm) The infrared region can be divided into two categories based on their radiation properties - the reflected IR, and the emitted or thermal IR. The reflected IR covers wavelengths from approximately 0.7 micrometres to 3.0 micrometres. The thermal IR covers wavelengths from appro...
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Electromagnetic Radiation

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Electromagnetic Energy Interactions When the energy being remotely sensed comes from the Sun, the energy: Propagates through the vacuum of space Interacts with the Earth's atmosphere, surface, and atmosphere (reflected, absorbed, transmitted); Reaches the remote sensor (interacts with various optical systems, filters, emulsions, or detectors); Electromagnetic Radiation Transfer of energy from one body to another in the form of electromagnetic waves is referred to as Electromagnetic Radiation. To understand how electromagnetic radiation is created, how it propagates through space, and how it interacts with other matter, it is useful to describe the processes using two different models popularly known as Electromagnetic Radiation Models:  the wave model; the particle model Wave Model of EM Energy An electromagnetic wave is composed of electric and magnetic vectors that are orthogonal to one another and travel from the source ...
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Basic of Remote Sensing V

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How is Energy Transferred? The energy can be transferred in the three basic ways: conduction, convection, and radiation. The transfer of energy by electromagnetic radiation (EMR) is of primary interest to remote sensing because it is the only form of energy transfer that can take place in a vacuum (the region between the Sun and the Earth). The Sun bathes the Earth’s surface with radiant energy causing the air near the ground to increase in temperature. The less dense air rises, creating convectional currents in the atmosphere. Energy may be conducted directly from one object to another as when a pan is in direct physical contact with a hot burner. Energy Interactions When Electro-Magnetic (EM) energy is incident on any given earth surface feature, three fundamental energy interactions are possible.  Reflection (ER) Absorption (EA) Transmission (ET) Incident Energy (EI) = reflected energy +  transmitted energy + absorbed energy Three forms...
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