Documents about Rayleigh Scattering
radar_lab5
Texas A&M, ATMO 489
Excerpt: ... sectional area is a function of target properties such as the size, shape, and kind of matter (i.e., complex refractive index; m = n ik, where n is the real and k is the imaginary component) and of radar properties such as the wavelength. When possible, radar meteorologists use scattering theory for relatively simple shapes such as spheres, spheroids, columns etc, which represent many hydrometeors fairly well, to calculate as a function of size, refractive index, and wavelength. The simplest assumption for shape is that of a sphere. As a result, it is the one most often used by radar meteorologists. When a sphere is large compared to the wavelength (i.e., diameter, D > 10), the backscattering cross-sectional area approaches the geometric area or r2 where r is the radius (r = D/2) of the sphere. [2] 1 When the size (i.e., diameter, D) of a sphere is small compared to the wavelength (i.e., D < 0.1), the sphere is in what is called the Rayleigh scattering region. In the Rayleigh region, is proportion ...
|
|
mar13_williams
Concordia Chicago, P 335
Excerpt: ... rious distances and the error bars once again correspond to 2 the 5% error from probe calibration. As in Fig. 6 the red lines correspond to monte carlo prediction at each distance. Because the monte carlo must be performed for each distance measurement, the prediction can only be presented as a piecewise function. In Fig. 7 the piecewise monte carlo prediction is plotted with arbitrary width at each distance. Once again the measurement of Rayleigh yield appears to match predicted values well at the 5% level. 5. Calibration of PMTs !NEEDS COMPLETION I.) Calibration of PMT a.) Measurement of energy and efficiency 6. Conclusion We measure accurately the energy of our laser using a high-sensitivity probe. The Rayleigh scattering cross section, a well known value, is then used to calculated the number of photons arriving at a PMT for given geometry. We have measured, with the use of these Rayleigh scattered photons as our source, the single photo-electron spectrum of PMTs. From this measurement we are able to fi ...
|
|
radar_study_guide_exam2
Texas A&M, ATMO 689
Excerpt: ... at scattering region the particle belongs in. Describe the relationship between the geometric area and the backscattering cross-sectional area of spheres in each backscattering regime. 6) List and describe typical maximum errors in associated with assuming Rayleigh scattering for D < 0.1 for both water and ice spheres. 7) If one instead defines the Rayleigh scattering regime as the maximum diameter (Dray) for which the absolute error in estimating < 25%, list Dray for water at S-band ( = 10 cm) 1 and X-band ( = 3.2 cm). Discuss why Dray is different for each wavelength. .List Dray for ice spheres at S-band. Explain why the definition of the " Rayleigh Scattering Regime" should be different for ice and water spheres. 8) List an expression for the backscattering cross-sectional area () for a sphere of diameter (D) in the Rayleigh scattering regime. From this expression, describe the dependence of on the dielectric function |K|2, diameter (D), or wavelength (). Given values for |K|2, D, and , calculate . 9) ...
|
|
radar_study_guide_exam2
Texas A&M, ATMO 489
Excerpt: ... gth of a radar wave and the size of a particle, determine what scattering region the particle belongs in. Describe the relationship between the geometric area and the backscattering cross-sectional area of spheres in each backscattering regime. 6) List and describe typical maximum errors in associated with assuming Rayleigh scattering for D < 0.1 for both water and ice spheres. 7) If one instead defines the Rayleigh scattering regime as the maximum diameter (Dray) for which the absolute error in estimating < 25%, list an approximate value for Dray given 1 water drops at S-band and W-band. Discuss why Dray is different for each wavelength. List Dray for ice spheres at S-band. Explain why the definition of the Rayleigh Scattering Regime should be different for ice and water spheres. 8) List an expression for the backscattering cross-sectional area () for a sphere of diameter (D) in the Rayleigh scattering regime. From this expression, describe the dependence of on the dielectric function | ...
|
|
me770_detailed_schedule
Wisconsin, ME 770
Excerpt: ... cturers specify 'how good their detector is' detector noise: expected noise in a simple Rayleigh scattering experiment detector noise: continued development of noise analysis in Rayleigh scattering HOMEWORK SET 1 DUE: CLICK FOR SOLUTION TO PROBLEM 1 HOMEWORK SET 1 DUE: CLICK FOR SOLUTION TO PROBLEM 2 HOMEWORK SET 2 ASSIGNED overview of cameras and camera noise camera, camera noise wrap-up data acquisition noise survey of 'good' digitizers for the 100 kHz - 10 GHz window HOMEWORK 3 ASSIGNED Filtering, Fourier transforms comparison of filtering and adjacent averaging (convolution) audio example: tada sound with filter FFT and the associated window choice applied to the example of spectral leakage the above example can also be used to demonstrate record-length:spectral-resolution and sample-frequency:nyquist HOMEWORK SET 2 DUE: click for summary of student results HOMEWORK 2: student solution part 1 HOMEWORK 2: student solution part 2 HOMEWORK 2: student solution part 3 SCOTT OUT OF TOWN - NO CLASS filtering exa ...
|
|
lecture34
Cornell, ECE 3030
Excerpt: ... Lecture 34 Electromagnetic Scattering In this lecture you will learn: Scattering of electromagnetic waves from objects Rayleigh Scattering Why the sky is blue Radar range equation ECE 303 Fall 2007 Farhan Rana Cornell University Scattering of Electromagnetic Waves from a Plane Interface x o o Hi Ei r ^ k = ki z Hr Ht t Et o Er r ^ k = kt z r ^ k = -ki z z=0 Incident, transmitted, and reflected waves are all plane waves The reflected and transmitted waves can also be called the scattered waves z ECE 303 Fall 2007 Farhan Rana Cornell University 1 Scattering of Electromagnetic Waves from Objects Incident plane wave: E i (r ) r r Scattered wave: E s (r ) r r o 1 phase fronts Questions: How does one find the scattered field? How much power from the incident field goes into the scattered field? In which direction(s) does the scattered power go? ECE 303 Fall 2007 Farhan Rana Cornell University Scattering ...
|
|
P534
Virgin Islands, P 534
Excerpt: ... uction Production of x-rays (x-ray tubes, x-ray spectra) 45 AB Radiation safety 6 CA Non-ionizing radiation 1 7 11 SZ X-ray attenuation and absorption, Thompson and Rayleigh scattering , Photoelectric effect, Compton effect, Pair production 12 17 AB Charged particles, stopping power, LET, exposure, dose, Kerma, heavy charged particles and neutrons 18 CA Non-ionizing radiation 2 19 21 WB Isotope treatment units, Betatrons, cyclotrons, LINACS, LINACS (detail) 22 SZ Modern techniques in radiotherapy (intro to IMRT, EPIDs) All Course Review EVALUATION Assignments First Half-Exam Final Exam Lecturers: 25% 30% 45% WB = Dr. Wayne Beckham, BCCA Vancouver Island Centre SZ = Dr. Sergei Zavgorodni, BCCA Vancouver Island Centre AB = Dr. Alistair Baillie, BCCA Centre for the Southern Interior CA = Dr. Cynthia Araujo, BCCA Centre for the Southern Interior Contacts for Vancouver Students: Dr. Cheryl Duzenli, BCCA Vancouver Centre TA TBA WB/July 2007 Physics 534, Radiotherapy Physics I Syllabus Fall ...
|
|
Lecture18
Lehigh, RM 1
Excerpt: ... Optical and Photonic Glasses Lecture 18: Rayleigh and Mie Scattering, Colloidal Metals and Photo-elastic Properties Professor Rui Almeida International Materials Institute For New Functionality in Glass Lehigh University Spring 2005 Lecture 18 Rui M. Almeida Colloration due to scattering Scattering can also cause a glass to become colored. E.g., if a cube of glass containing small particles is traversed by a beam of white light, it may look bluish when viewed from the side, but the light emerging in the beam direction will be reddish, because blue is more strongly scattered than red. Rayleigh showed that fluctuations of the refractive index cause scattering, designated as Rayleigh scattering . If a beam of unpolarized light, Io, is scattered only once by a spherical (as well as insulating and non-absorbing) particle of diameter < /10, the scattered intensity measured at a distance d from the particle may be expressed as: Is = Io (92V2 / 2d24) [(m2-1)(m2+2)]2 (1+cos2) where V is the particle volume, is the ...
|
|
308_LN_Wk13
St. Lawrence, IT 308
Excerpt: ... the simplest example to study, and would help us should we decide to tackle the other types of sources, and (b) it allows us to understand two interesting physical systems: the linear antenna - as either an emitter or receiver - and the individual oscillating atoms and/or molecules that give rise to the Rayleigh scattering that makes the Earth's sky appear blue. We will cover the derivation given in this section of the book. Look over it. The important thing about this derivation is the notion of 'retarded potentials' (`delayed potentials' might be an apter name). These potentials arise because you need to account for the fact that the field one light year away from a dipole, for example, is the result of the dipole's condition one year ago, and not of its present condition: it takes an electric field time to propagate through space. When we take the perfect dipole approximation limit, this derivation leads to an electromagnetic wave whose power is proportional to the fourth power of the frequency at which ...
|
|
5 Radiation and Energy Balance
Maryland, GEOG 345
Excerpt: ... ) negative feedback (i.e. clouds?) Heating of the lower atmosphere Fig. 2-13, p. 44 Incoming solar radiation: scattering Rayleigh scattering : efficiency varies with -4 air molecules causes blue sky Mie scattering: efficiency is less wavelength dependent cloud droplets, larger aerosol particles theory for spherical particles Rayleigh scattering Fig. 2-14, p. 45 Rayleigh scattering Fig. 5, p. 46 Rayleigh scattering Fig. 6, p. 46 Mie scattering Fig. 7, p. 46 Reflection Reflection varies between surface type and even between different conditions of the same surface Average planetary albedos are relatively stable Table 2-3, p. 44 Incoming solar radiation direct radiation: direct sunbeam diffuse radiation: scattered and reflected sunlight Fig. 2-15, p. 45 Surface-atmosphere energy balance Note: solar only daytime; infrared day and night Fig. 2-16, p. 47 Variation of energy balance by latitude This contrast is the primary dri ...
|
|
radar_lab6
Texas A&M, ATMO 489
Excerpt: ... rror associated with assuming Rayleigh scattering , (Mie - Ray)/ Mie * 100% versus the size parameter = 2r/ for S-band (10 cm) for ice spheres at T=0C. Discuss how your new results compare with your laboratory #5 results for water spheres. 5. (8 points) If you define Rayleigh scattering region as the maximum diameter (Dray) for which absolute error < 25%, what would Dray be for ice spheres (e.g., hail) at T=0C for S-band? Compare and contrast your new result with your laboratory #5 result for water spheres. Is the definition of the " Rayleigh Scattering Regime" the same or different for ice and water spheres? Discuss. 6. (8 points) Using results from parts 1) and 2) above, calculate |K|2 for water and ice at S-band and W-band, assuming T=0C. What would be the consequence of using the Sband |K|2 in the calculation of backscattering cross-sectional area () at W-band? 7. (8 points) Assuming S-band (10 cm) and Rayleigh scattering , hand calculate of a water sphere of diameter D = 5 mm (show your work). Repeat y ...
|
|
Chapter19a
University of Florida , MET 1010
Excerpt: ... y emit and/or interact with light (reflection, transmission, absorption, refraction, scattering, diffraction) Perception of color: Each color corresponds to a particular wavelength. White: all wavelengths are present with equal intensity; Black: no light is emitted and/or reflected from the object. Color of emitted light and temperature: The sun appears white. Colder stars look redder ( max is longer than Hotter stars look bluer ( max is shorter than max of the sun). max of the sun). Scattering of light The scattering of light in the atmosphere depends on the size of the scattering particles, R, and on the wavelength, , of the scattered light. Geometric scattering: R> Rain drops (R~10-100 m) All wavelengths equally scattered Optical effects: white clouds Mie scattering: R~ Aerosols (R~0.01-1 m) Red scattered better than blue Blue moon, blue sun Rayleigh scattering : R< Air molecules (R~0.0001-0.001 mm) Blues scattered better than red Blue sky, blue mountains, red ...
|
|
PS5_2008
Cornell, ASTRO 212
Excerpt: ... Astronomy 212 Problem Set 5 Due Monday April 7 1. Haze optical depth in the Earth's atmosphere (20 points.) (In this problem, neglect the molecular scattering of the gaseous constituents in the atmosphere.) On a somewhat hazy day the horizontal visibility near the surface of the Earth might be about 10 km, limited by aerosols. The typical size of these particles is about 1 micron in diameter. Assume that the particles are spherical, that their cross section for intercepting visible light is given by their geometrical cross section, and that a visibility of 10 km implies that the optical depth reaches unity for a radiation path length of 10 km. (a) (15 points) Find an algebraic expression for the number density of particles (assumed uniform along the 10 km path) in terms of the path length and the particle diameter. (b) (5 points) Evaluate the number density numerically, in units # m-3 and in units # cm-3. 2. Rayleigh scattering optical depth of the Earth's atmosphere (30 points). In this problem assume cle ...
|
|
Lec22
Georgia Tech, ATOC 5235
Excerpt: ... een any of the emitted photons 1 Properties of laser light: Monochromaticity Coherence Beam divergence: All photons travel in the same direction; the light is contained in a very narrow pencil (almost COLLIMATED), laser light is low in divergence (usually). High irradiance: Let's estimate the irradiance of a 1 mW laser beam with a diameter of 1 mm. The irradiance (power per unit area incident on a surface) is F = P/S = 1x10-3 W/( (1x10-3 m)2/4) = 1273 W/m2 Elastic scattering is when the scattering frequency is the same as the frequency of the incident light (e.g., Rayleigh scattering and Mie scattering). Inelastic scattering is when there is a change in the frequency. 2 Optical interactions of relevance to laser environmental sensing Rayleigh scattering : laser radiation elastically scattered from atoms or molecules with no change of frequency Mie scattering: laser radiation elastically scattered from particulates (aerosols or clouds) of sizes comparable to the wavelengths of radiation with no ...
|
|
smoke_blue color
George Mason, EOS 759
Excerpt: ... o as I=I o eko - - r2 e-ko - =eko - r2 e-ko - e- ; o o 1 I=I o ro eko - - e-ko - =eko - r2 e-ko ; o Rayleigh scattering 's wavelength dependence (1=4 ) comes into the solution to Eqs. (1) and (2) through the optical depth. The vertical optical depth of the cloud C is C o o =4 : 5 2 where I is the scattered light, I o is the incident light (sunlight), and is wavelength. is the optical depth at any point inside the cloud whose total optical depth is o at a reference wavelength o , here chosen as 0:5 m. We have taken I o to be a 5700 K Planck function to represent the incident solar sunlight. The extinction parameter k is k 1 - o 1 - go 1=2 ; 3 At shorter wavelengths, the optical depth is significantly higher than it is at longer wavelengths. For example, when o 1 at o 0:5 m, the cloud optical depths C at 0.4 and 0:7 m are 2.44 and 0.26, respectively. The justification for approximating the wavelength dependence of the extinction cross section of smoke p ...
|
|
4b-RadiationAtmosInfl_nf
Indiana, GEOG 109
Excerpt: ... Atmospheric Influences on Radiation Readings A&B: Ch 3. (p. 56-68) Topics: 1. Reflection and Scattering a. Rayleigh Scattering b. Mie Scattering 2. 3. 4. 5. Absorption Transmission Atmospheric Window Greenhouse Effect G109: Weather and Climate Atmospheric Reflection and Scattering Reflection: Scattering: Specular Reflection (Mirror) Two types: Diffuse Reflection or Scattering G109: Weather and Climate 4: Radiation Rayleigh Scattering Rayleigh Scattering : scatter and in The blue end of the visible range is preferentially scattered tend to more, G109: Weather and Climate 4: Radiation Rayleigh Scattering Near sunrise or sunset Radiation must traverse a longer pathlength More short wavelengths (blue light, as well as green light) Light that is transmitted to the surface is mostly G109: Weather and Climate 4: Radiation Mie Scattering Mie Scattering: tend to scatter equally, and more Both scattered and transmitted light are a mixture of all wavelengths: ...
|
|
Phys406_PS10
New Mexico, PHYS 406
Excerpt: ... that 1 e2 d! 2 2 is the "classical electron radius". # r cos $ , where rc = 4!" 0 mc 2 d" c This is known as "Thompson scattering". Note the scattering cross section is independent of the frequency of the incident wave. Also note, this formula breaks down when the wavelength is so short that the energy of the photon is on the order of the rest mass of the charge. At that point quantum mechanics kicks in, and the process is known as "Compton scattering". (c) For frequencies well below resonance, the polarizability is approximately that of a DC field. In case, show that 4 d! 2% $ ( # rc ' * cos2 + . d" & $0 ) This is known as " Rayleigh scattering ". Note that the scattering cross section is highly frequency dependent. (d) Rayleigh scattering tells us that the sky is blue and sunsets are red. Explain. ...
|
|
Lecture16
Colorado, LIDAR 2008
Excerpt: ... Rayleigh scattering also undergoes Doppler shift and broadening, however, it is not frequency discriminated. In other words, when scanning a laser frequency, the backscattered Rayleigh signal gives nearly the same Doppler broadened line width, independent of laser frequency. Thus, the atmosphere molecule scattering does not provide frequency discrimination. A frequency analyzer must be implemented into the lidar receiver to discriminate the return light frequency, i.e., analyze Rayleigh scattering spectrum to infer wind and temperature. - Rayleigh Doppler technique Resonance Fluorescence Doppler versus Rayleigh Doppler Relative Intensity (Arb. Unit) Fe Absorption 1.4 Rayleigh scattering free of aerosols 1.2 1 0.8 0.6 0.4 0.2 0 -40 -20 0 20 40 Frequency Offset (Arb. Unit) Relative Intensity (Arb. Unit) Na Absorption 2 1.5 Aerosol Scattering Molecular Scattering 1 0.5 0 -40 -20 0 20 40 Frequency Offset (Arb. Unit) Resonance Fluorescence Doppler versus Rayleigh Doppler Doppler Effect in Rayle ...
|
|
Chapter19a
University of Florida , MET 1010
Excerpt: ... color. We see the objects because they emit and/or interact with light (reflection, transmission, absorption, refraction, scattering, diffraction) Perception of color: Each color corresponds to a particular wavelength. White: all wavelengths are present with equal intensity; Black: no light is emitted and/or reflected from the object. Color of emitted light and temperature: The sun appears white. Colder stars look redder (max is longer than max of the sun). Hotter stars look bluer (max is shorter than max of the sun). Scattering of light The scattering of light in the atmosphere depends on the size of the scattering particles, R, and on the wavelength, , of the scattered light. Geometric scattering: R> Rain drops (R~10-100 m) All wavelengths equally scattered Optical effects: white clouds Mie scattering: R~ Aerosols (R~0.01-1 m) Red scattered better than blue Blue moon, blue sun Rayleigh scattering : R< Air molec ...
|
|
4230NotesSet23
Maple Springs, EATS 4230
Excerpt: ... time after the pulse is fired. The density of scattering particles, e.g., air molecules in the case of Rayleigh scattering , will be higher closer to the ground so that the intensity of the backscattered radiation will decrease with height. Also, the source of the backscattering is progressively further away from the telescope aperture the amount of detected backscatter radiation will decrease as 1/z, where z is the height from which the up-going pulse of photons is scattered. The most important property of all of this is that the radiation backscattered from each altitude will be received at the ground at a different delay time after the pulse of radiation was launched upwards, i.e., radiation back-scattered from altitude z will be received at t = 2z/c seconds after the pulse was launched where c is the speed of light. The factor of two here should be obvious. To put this in perspective, radiation back-scattered from 1 km above the surface will be received about 6.7 sec after the pulse is launched; and radi ...
|