The following subsections explain the classification of remote sensing. The adverse influences of overexposure or underexposure to emr accumulate over time, and their consequences. Why are people interested in the interaction between emr and soil. This electromagnetic radiation travels through the atmosphere before falling onto the earth surface objects.
Visible light is the only part of the electromagnetic spectrum that humans can see with an unaided eye. Interaction of electromagnetic radiation with matter. According to white 1977, remote sensing includes all methods of obtaining pictures or. Nuclear reactions within the sun produce a full spectrum of electromagnetic radiation.
Many individuals undergo an xray to allow medical professionals to gain a. Most remote sensing systems are passive sensors, i. Introductory remote sensing wk 2 22 emr units note. The four laws of radiation learning weather at penn state. Electromagnetic radiation properties and laws just btech. The infrared region can be divided into two categories based on their radiation properties the reflected ir, and the emitted or thermal ir.
How electro magnetic radiation interacts with atmosphere. Radiation remote sensing components an ideal remote sensing system may have the following components 1. Aug 26, 2015 objectives what is meant by electromagnetic energy electromagnetic radiation emr spectrum source of radiationenergy in remote sensing 19 20. Oct 14, 2015 the term remote sensing means the sensing of the earths surface from space by making use of the properties of electromagnetic waves emitted, reflected by the sensed objects, for the purpose of improving natural resources management, land use and. 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. Electromagnetic radiation emr is a carrier of electromagnetic energy by transmitting the oscillation of the electromagnetic field through space or matter. The longer the wavelength, the lower the frequency. While remote sensing is the technology of obtaining information about the earth and its environment, gis is the technique or. The parameters that characterize a wave motion are wavelength.
Remote sensing is the science and art of identifying, observing, and measuring an object without coming into direct contact with it. Geometric aspects of imagery image visualization and enhancement visual interpretation of remote sensing images image and tables arithmetic in combination with practical vegetation indexes reading and calculation in combination with practical. All energy moving in a harmonic sinusoidal wave pattern with a velocity equal to that of light harmonic pattern means waves. The waves are due to a disturbance at the airwater interface. An electromagnetic wave is composed of electric and magnetic vectors fields that are perpendicular to one another. Interaction of emr with atmosphere and earth surface the sun is the source of radiation and electromagnetic radiation emr from the sun that is reflected by the earth and detected by the satellite or aircraftborne sensor must pass. Review remote sensing land surface temperature for. In case of reflection and refraction of electromagnetic radiation. All electromagnetic radiation has fundamental properties and. Electromagnetic radiation emr and its application in remote. Manual interpretation and analysis dates back to the early beginnings of remote sensing for. Wave model of electromagnetic radiation in the 1860s, james clerk maxwell 18311879 conceptualized electromagnetic radiation emr as an electromagnetic wave that travels through space at the speed of light, c,whichis3x108 meters per second hereafter referred to as m s1 or 186,282. Introduction to electromagnetic radiation emr wave and particle theory emr interactions in the atmosphere.
The composition of the atmosphere is thus of importance in remote sensing because emr must pass through it. Next we will be examining the way in which we categorize electromagnetic radiation for just that purpose. Elements of remote sensing multiple choice questions and answers pdf free download for civil engineering students. The process of remote sensing involves an interaction between incident radiation and the targets of interest. One of the implications of this relationship to remote sensing is that it is more difficult to detect the radiant energy of longer wavelength than shorter wavelengths less energy to detect. Electromagnetic radiation emr and its application in. Lecture 2 understanding electromagnetic radiation emr. Objectives what is meant by electromagnetic energy electromagnetic radiation emr spectrum source of radiation energy in remote sensing 19 20. Process of remote sensing 1 energy source or illumination a the first requirement for remote sensing is to have an energy source which illuminates or provides electromagnetic energy to the target of interest. Low frequency long wavelength electromagnetic radiation carries little energy. Instead, you just need to know the fundamental principles describing the electromagnetic radiation that originates from an object, and how that radiation travels through space discussed in the next section. Emr radiation and its interactions with atmosphere and earth. Firstly because soil mapping holds information on topography, geology, gemorphology and hydrology. Digital thermal infrared thermal ir sensors do not detect reflected radiation, they are tuned to respond to emitted heat.
The characteristics of objects can be determined using reflected or emitted emr from the object. Electromagnetic radiation properties and laws leave a comment remote sensing by srinivasjbt january 12, 2019 january 12, 2019 in the previous article, we have defined what is remote sensing and what are various constituents or stages of remote sensing. The visible and infrared portions of the electromagnetic spectrum are the most important for the type of remote sensing discussed in this course. In biology it is often a part of the discussion of photosynthesis, the physiology of the eye, and mutagenic sources. Infrared radiation is most commonly used in remote sensing as infrared sensors collect thermal energy, providing us with weather conditions. Source of remote sensing data is the electromagnetic radiation reflected or emitted from an object. A radio detects a different portion of the spectrum, and an xray machine uses yet another portion. Because radiation can transport energy without a medium, it is the only way in which the earth interacts with the rest of the universe. Use of remote sensing american university of beirut. Electromagnetic radiation emr basics for remote sensing. Em waves are energy transported through space in the form of periodic.
Concepts of remote sensing electromagnetic radiation. To which part of the electromagnetic spectrum does this wave belong. How useful is the electromagnetic spectrum to remote sensing. Electromagnetic radiation principles and blackbody radiation. In the 1860s, james clerk maxwell 18311879 conceptualized electromagnetic radiation emr as an electromagnetic wave that travels through space at the speed of light, c, which is 3 x 108 meters per second hereafter referred to as m s1 or 186,282. Natural sources of electromagnetic radiation all objects with a temperature above absolute zero 273oc, 0k emit emr continuously. Emr transmit cross space in the wave form and in the speed of light. Radiation in the reflected ir region is used for remote sensing purposes in ways very similar to radiation in the visible portion. Electromagnetic radiation emr from the sun and from indoor lamps, emissive displays, and other artificial sources have wavelengthspecific and dosedependent effects on underlying life processes that determine health status. Electromagnetic radiation natural resources canada. Electromagnetic energy travels in waves and spans a broad spectrum from very long radio waves to very short gamma rays. This energy is in the form of electromagnetic radiation emr. The interaction process is of great importance to the sensing applications that characterize material media. Electromagnetic radiation electromagnetic radiation exhibits wavelike behaviour as it travels through space.
This involves the detection and measurement of radiation of different wavelengths reflected or emitted from distant objects or materials, by. Electromagnetic radiation emr or energy interactions with atmosphere and with the earth surface play a vital role in remote sensing. In physics, electromagnetic radiation em radiation or emr refers to the waves or their quanta, photons of the electromagnetic field, propagating radiating through space, carrying electromagnetic radiant energy. Radiation and the atmosphere b as the energy travels from its source to the target, it will come in contact with and interact with. In the atmospheric sciences, electromagnetic radiation is commonly referred to as simply radiation. While travelling, various particles and gaseous molecules present in the atmosphere interacts with electromagnetic radiation. Radiant energy energy propagating through space at the speed of light in the.
Elements of remote sensing multiple choice questions. Optical remote sensing systems, our eyes included, are generally called passive systems because they only detect incident electromagnetic radiation that has been reflected and transmitted back up through the atmosphere. Apr 23, 2017 chapter two electromagnetic energy and remote sensing 2. Electromagnetic radiation emr and remote sensing uri edc. An electromagnetic wave is characterized by a frequency and a. Electromagnetic radiation is energy that interacts with matter. More specifically, all objects with a temperature above absolute zero emit radiation. Undoubtedly, you know that electromagnetic radiation emr is a risky factor for human health, and under some circumstances a lot of health problems can be caused by emr exposure. Light consists of oscillating electrical fields denoted e above, and magnetic fields denoted. Sensor to detect and record the change in electromagnetic energy remote sensing processes energy source or illumination a radiation.
The term remote sensing means the sensing of the earths surface from space by making use of the properties of electromagnetic waves emitted, reflected by the sensed objects, for the purpose of improving natural resources management, land use and. A source of electromagnetic radiation or emr sun transmission of energy. The energy is in the form of electromagnetic radiation. Core principles of electromagnetic radiation emr solar radiation blackbody concept and radiation laws emr and remote sensing wave and particle models of radiation regions of em spectrum radiation geometry, terms, units interaction with atmosphere interaction with surface. Depending on the predominant source of electromagnetic energy in the remote sensing system, the remote sensing. Know basics of remote sensing quickly and become expert. Introduction to the electromagnetic spectrum science. Interaction of electromagnetic radiation with matter energy can occur in different forms e g chemical, electrical and thermal energy. It includes radio waves, microwaves, infrared, visible light, ultraviolet, xrays, and gamma rays classically, electromagnetic radiation consists of electromagnetic waves. Emr forms the basis for remote sensing rs, which has gained great relevance in studying and.
Medium which interacts with this energy atmosphere 3. Topology describes the geometric characteristic of objects which do not change under transformations and are independent of any coordinate system. All electromagnetic waves travel through space at the same speed, c 2. Concept of remote sensing remote sensing is the latest tool of study in earth sciences in general and geographical studies in particular. Molecular absorption converts the radiation energy into excitation energy of the molecules. The phrase electromagnetic spectrum is frequently referred to in the study of science. Emr radiation and its interactions with atmosphere and earth content writer. Emr the foundation of remote sensing technology is based on the measurement and interpretation of the patterns of emr. Because radiation can transport energy even without a medium, it is the only way in which the earth interacts with the rest of the universe. Optical remote sensing depends on solar radiation as the source of illumination. A fundamental requirement for remote sensing is the detection of electromagnetic radiation emr by sensors on a remote sensing platform. Emission of electromagnetic radiation, or emr sunself emission.
Sources of electromagnetic radiation remote sensing uses emr from both natural sources and artificial sources. Electromagnetic waves are energy transported through space in the form of periodic disturbances of electric and magnetic fields. Remote sensing and geographical information system gis. Energy interactions with atmosphere and earth surface. However, modern remote sensing means acquiring information about earths land and water surfaces by using reflected or emitted electromagnetic energy. In remote sensing, the sun is the most obvious source of emr solar radiation, although all. Energy interactions with the atmosphere dictates the spectral regions through which only we can do the remote sensing which are known as spectral windows the spectral regions where atmosphere is more. Electromagnetic radiation emr basics for remote sensing handouts objectives. Electromagnetic radiation is the very basis for remote sensing technology. Hence, the main elements in the process of data collection in remote sensing are the object to be studied, the observer or sensor, the emr that passes between these two, and the source of the emr.
Electromagnetic radiation emr plays an important role in the process of remote sensing. This picture represents a snap shot in midinfrared light. Remote sensing is concerned with the measurement of emr returned by earth surface. Lectures 2 and 3 electromagnetic energyis generated by several mechanisms, including changes in the energy levels of electrons, decay of radioactive substances, and the thermal motion of atoms and molecules. Humans accomplish this task with aid of eyes or by the sense of smell or hearing. It is either natural originating from the sun or earth by emission, or by artificial means. The human eye can only detect only a small portion of this spectrum called visible light. Study guide electromagnetic spectrum everything with heat 0 k with heat 0 k emits electromagnetic radiation emr emr is a combination of electrical and magnetic waves waveform sinusoidal speed of light c c3x108 msec c. According to laws of nature, each object has its own unique and different characteristics of reflection or emission, depending upon different. For electromagnetic radiation, there are four laws that describe the type and amount of energy being emitted by an object. Electromagnetic radiation principles and blackbody.
From the following definitions, we can have a better understanding about remote sensing. Principles of remote sensing centre for remote imaging. Depending on the predominant source of electromagnetic energy in the remote sensing system, the remote sensing can be passive or active. This is useful as different objects emit emr in different ways, so the spectral response can be analysed. Electromagnetic radiation emr and sensors remote sensing system, platforms and sensors. When electromagnetic radiation travels through the atmosphere, it may be absorbed or scattered by the constituent particles of the atmosphere. Elements of remote sensing mcqs pdf download posted on august 19, 2018 april 18. What is the role of electromagnetic radiation in remote.
In earth and space science electromagnetic radiation is often a part of a. These important terms are further explained in the course textbook. This involves the detection and measurement of radiation of different wavelengths reflected or emitted from distant objects or materials, by which they may be identified and categorized. A source of electromagnetic radiation or emr sun transmission of energy from the source to the surface of the earth, through. Active sensors like radar transmit energy in a certain direction and records the portion reflected back by features within the signal path. The electromagnetic spectrum natural resources canada.
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