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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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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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Basic of Remote Sensing II

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Remote Sensing Process A. Energy Source or Illumination – the first requirement is to have an energy source which illuminates or provides electromagnetic energy to the target of interest. B. Radiation and the Atmosphere – as the energy travels from its source to the target, it will come in contact with and interact with the atmosphere it passes through. This interaction may take place a second time as the energy travels from the target to the sensor. C. Interaction with the Target – once the energy makes its way to the target through the atmosphere, it interacts with the target depending on the properties of both the target and the radiation. D. Recording of Energy by the Sensor – after the energy has been scattered by, or emitted from the target, we require a sensor to collect and record the EMR. E. Transmission, Reception, Processing – the energy recorded by the sensor has to be transmitted, often in electronic form, to receiving and processing station where the data a...
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