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Topic: Reflectivity

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In the News (Wed 19 Jun 19)

  Reflectivity - Wikipedia, the free encyclopedia
In optics, reflectivity is the reflectance (the ratio of reflected power to incident power, generally expressed in decibels or percentage) at the surface of a material so thick that the reflectance does not change with increasing thickness; i.e.
Surface reflectance may be subdivided into diffuse or Lambertian reflectance and specular reflectance.
The apparent reflectance for an ideal Lambertian surface is independent of the observer's angle of view.
en.wikipedia.org /wiki/Reflectivity   (166 words)

 An Ethnographic Study of Therapist Development and Supervisee Reflectivity
Reflectivity is integral to therapist development across the life span and differentiates therapists who continue to grow and develop throughout their career from therapists who stagnate (Skovholt and Ronnestad, 1995; Neufeldt et al., 1997).
Given the importance of reflectivity to therapist development, the primary research goal was to understand and describe student perceptions of the ways in which this particular training context facilitated and/or hindered the learning and use of reflectivity.
A central assumption of the reflecting team format and a solution-focused approach to supervision is that the inquisitive, curious stance of mutual exploration between supervisor and trainee in a positive relational context will facilitate in the trainee the skill and long-term motivation for self-reflection.
www.rapidintellect.com /AEQweb/mo1052l1.htm   (2662 words)

 Ji: Angle-dependent reflectivity
Since reflectivity imaging is an inversion from seismic data collected at the surface, it is important to understand the implied forward model that relates the reflectivity to surface seismic data.
(), the reflectivity is obtained by deconvolving the downgoing wavefield from the upcoming wavefield in the
Figure 7 Angle-dependent reflection coefficient as a function of the angle of incidence: (a) the theoretical result, (b) the result of profile imaging with conventional imaging condition, (c) the result of profile imaging with de Bruin's imaging condition, and (d) the result of planewave synthesis imaging.
sepwww.stanford.edu /public/docs/sep84/jun1/paper_html   (1922 words)

 National Doppler Radar Sites
The radar's computers measure the phase change of the reflected pulse of energy which then convert that change to a velocity of the object, either toward or from the radar.
Base Reflectivity images are available at several different elevation angles (tilts) of the antenna and are used to detect precipitation, evaluate storm structure, locate atmospheric boundaries and determine hail potential.
Although the Composite Reflectivity product is able to display maximum echo intensities 248 nm from the radar, the beam of the radar at this distance is at a very high altitude in the atmosphere.
weather.noaa.gov /radar/radinfo/radinfo.html   (2949 words)

 About Nexrad : Weather Underground
"Reflectivity" is the amount of transmitted power returned to the radar receiver after hitting precipitation, compared to a reference power density at a distance of 1 meter from the radar antenna.
Base reflectivity images are available at several different elevation angles (tilts) of the antenna; the base reflectivity image currently available on this website is from the lowest "tilt" angle (0.5°).
The base reflectivity images in Precipitation Mode are available at four radar "tilt" angles, 0.5°, 1.45°, 2.40°, and 3.35° (these tilt angles are slightly higher when the radar is operated in Clear Air Mode).
www.wunderground.com /radar/help.asp   (3006 words)

 Reflectivity in Minerals
The reflectivity is measured by observing the incident and reflected light at different wavelengths.
The reflective index is the percentage of light that bounces off the solid surface and is not absorbed.
Reflectance measurements for opaque minerals consists of a table of wavelength values versus % reflectivity at that wavelength.
webmineral.com /help/Reflectivity.shtml   (598 words)

 Reflectivity Data
Reflectivity calculated for specific bandwidths is needed for the calculation of total column ozone from TOMS instrument.
Reflected radiation can come from two surfaces, the ground, and the tops of clouds.
Reflectivity is determined from the measurements at 380 nm, or 360 nm in the case of Earth Probe.
toms.gsfc.nasa.gov /reflect/reflect.html   (112 words)

 CREWES Reflectivity Explorer   (Site not responding. Last check: 2007-10-22)
Bortfeld approximation: Bortfeld, R. (1961) Approximations to the reflection and transmission coefficients of plane longitudinal and transverse waves.
The first is the zero-offset reflection coefficient, the second depends on the square of the sine of the average P-wave angle, and the third essentially depends on fourth and higher even-order powers of the sine.
The impedance contrast includes a large portion of the density contrast, and the remaining density contrast term, being relatively small, is dropped.
www.crewes.ucalgary.ca /Samples/ReflEx/ReflectivityExplorer.html   (1307 words)

 National Radar Reflectivity Mosaic FAQ's
The mosaic is composed of the highest observed reflectivity category within map grid boxes approximately 10 km (~5 nautical miles) on a side.
The reflectivity categories indicate the density of precipitation backscatterers (raindrops, snowflakes, hailstones, or ice pellets) within the lowest 10,000 feet of the atmosphere.
Though the WSR-88D detects reflectivity at much higher spatial and temporal resolution and with greater precision than that appearing in the Radar Coded Message, the reduced data format was chosen due to communications limitations present during the early part of the radar network's life cycle, in the late 1980's and early 1990's.
www.srh.noaa.gov /srh/sod/radar/radinfo/about.html   (576 words)

 Radar Imagery Basics   (Site not responding. Last check: 2007-10-22)
Base Reflectivity corresponds to the amount of energy that is scattered or reflected back to the radar by whatever targets are located in the radar beam at a given location.
The amount of reflective signal is a relative indicator of rain or hail intensity.
Base Reflectivity images are available at several different elevation angles of the antenna and are used to detect precipitation, evaluate storm structure, locate atmospheric boundaries and determine hail potential.
www.mnsu.edu /weather/wx_WALTER/Modules/Radar/radar_edu.html   (2068 words)

 Two Liminal Phenomena: The Non-Discursive Reflectivity And Its Absence
Reflectivity exists because human language exists, that is why the foundations of teaching and mastering reflectivity (for the sake of the ability of a better understanding) have a strong "linguistic smell", but the atmosphere of enhanced reflectivity has no alternative for its installation: every representative of intellectual activities must pass through the school of interpretation.
Reflectivity is the second source of experience, sensorics being the first, and for example artistic effects are more reflective than sensory, artisticity of a text being the optimal measure of reflectivity awakened.
Reflectivity of the ontological type (controlling only the progressive movement of knowledge)> of the methodological type (controlling the changing of all ideal realities involved in the mastery of the world into instruments of the further processes of mastering the world).
limen.mi2.hr /limen2-2001/bogin.html   (10664 words)

 Radar reflectivity and radial velocity remapping & mosaicing
For each LAPS grid point, the remapping algorithm computes reflectivity by taking the mean Z value of all gates lying within a grid volume centered on the LAPS grid point.
The use of all gates (rather than just the nearest neighbors) is advantageous in that it allows all of the radar information to influence the analysis and mitigates any noise that could be introduced by sub-sampling or spatial aliasing.
QC flags would not however be averaged in with valid reflectivity values to "dilute" the radar echoes.
laps.fsl.noaa.gov /albers/remapper_laps.html   (1124 words)

 Airborne Cloud Radar (ACR) Reflectivity, Wakasa Bay, Japan
Reflectivity and velocity data are structured as two-dimensional arrays, where altitude and time are the two dimensions.
Reflectivity is given in units of mm^{6} m^{-3}.
Note that some clear-air regions have reflectivity values that are slightly negative, due to the noise characteristics of the signal when no target is present.
nsidc.org /data/docs/daac/nsidc0212_rainfall_wakasa_acr.gd.html   (967 words)

 Ji & Palacharla: Angle-dependent reflectivity
Even though the objective of AVO analysis is to observe an anomalous angle-dependent reflectivity behavior of a reflector, the name amplitude versus offset was chosen because most of the amplitude analysis is done in the common midpoint domain.
Since profile imaging theoretically provides a reflectivity map for the subsurface image, we can construct angle-dependent reflectivity panels with the help of additional information, namely, the incidence angle of the wavefield at a given subsurface point.
The theoretical angle-dependent reflectivity behavior of the second reflector, shown in Figure rflcoeff, was calculated with Zoeppritz equations.
sepwww.stanford.edu /public/docs/sep80/jun2/paper_html   (1177 words)

 FSL Model Verification: A Collection of Case Studies for Mesoscale Circulations
15 h surface forecast of closeup of wind and reflectivity for "Pueblo Cyclone" valid 0900 UTC on 27 June.
19 h surface forecast of closeup of wind and reflectivity for "Pueblo Cyclone" valid 1300 UTC on 27 June.
20 h surface forecast of closeup of wind and reflectivity for "Pueblo Cyclone" valid 1400 UTC on 27 June.
laps.fsl.noaa.gov /szoke/mesoconf/cases_homepage.html   (8446 words)

 WHT mirror reflectivity   (Site not responding. Last check: 2007-10-22)
The V-band reflectivities of the WHT primary, secondary and Nasmyth (tertiary) mirrors are measured at regular intervals with a hand-held reflectometer.
The UV reflectivity cannot be measured with the reflectometer, and experience at other telescopes suggests that it might not be fully restored by snow-cleaning.
The UV/V reflectivity ratio (measured more accurately than the absolute values) was within a few % of the expected values when measured in Jan and Jul 1999, and in Feb 2000, suggesting that snow cleaning is as effective in the UV as at V band.
www.ing.iac.es /~crb/wht/mirror.html   (406 words)

 US Composite Reflectivity (2km by 2km) from National Weather Service Radars
The WSI radar reflectivity data is in image form with a size of 1837 rows by 3661 columns and has a resolution of 2 km by 2 km.
The distribution of the 15 minute reflectivity data is restricted to educational or non-commercial research purposes and can only be distributed after 48 hours of data acquisition.
Researchers and educators receiving the 15 minute instantaneous reflectivity data are prohibited from redistributing this data for any purpose or use.
ghrc.msfc.nasa.gov /uso/readme/reflectivity.html   (687 words)

 Cool Metal Roofing: FAQs
Reflectivity is defined as the ratio of the reflected solar radiation flux to the incident flux.
The negative impact of high reflectivity in the winter months is minimized by the low angle of the sun and short daylight hours.
The fact that the IR reflective pigments absorb less heat should actually prolong their lifespan thus resulting in better durability for the products on which they are used.
www.coolmetalroofing.org /faqs.htm   (5210 words)

 Reflectivity and Absorption   (Site not responding. Last check: 2007-10-22)
Tell the class to watch the posterboard as you shine the flashlight on the three different surfaces trying to reflect the light off the surface and on to the posterboard.
It is important that the students understand that the mirror (and white paper somewhat) reflects the sunlight and absorbs little.
To demonstrate the idea of absorption an reflection, drop 4 tablespoons of water from a cup onto a block of wood.
faldo.atmos.uiuc.edu /w_unit/LESSONS/reflectivity.absorption.html   (840 words)

 The Relationship Between Low-Elevation WSR-88D Reflectivity and Hail at the Ground Using Precipitation Observations ...   (Site not responding. Last check: 2007-10-22)
The primary goal of this study is to determine whether a single reflectivity threshold can be used to reliably discriminate between the hailfall and rainfall regions within typical springtime thunderstorms in the southern plains.
The Level II data are the radar base data (reflectivity, Doppler velocity and spectrum width), which are collected at an azimuthal increment of 1° and at a range increment (gate spacing) of 1 km for reflectivity and 250 m for velocity and spectrum width.
1 that, as reflectivity increases, the percentage of no-hail observations steadily decreases, until, at a threshold of 60 dBZ, hail was always observed.
www.nssl.noaa.gov /swat/SLS18/slscon96.aw.html   (1580 words)

We assume a neutron beam reflecting on a flat surface with an incident angle theta.
With this equation, you can calculate the reflectivity at the last interface (last layer/bulk), and then recursively calculate the reflectivity at each interfaces, and so obtain the reflectivity of the air/first layer interface.
Specular reflectivity cannot distinguish between roughness and interdiffusion if the size of the imperfection of the surface is smaller than the coherence length of the neutron wave (which is of the order of the micron in the reflectivity conditions).
www-llb.cea.fr /menl/ref/reflecto/reflecto1.html   (697 words)

 Doppler Radar Frequently Asked Questions
The base reflectivity image currently available on this website is from the lowest "tilt" angle (0.5°).
This is an image of estimated one-hour precipitation accumulation on a 1.1 nm by 1 degree grid.
Otherwise, at the higher elevations (2.5°, 3.5°, and 4.5°) a single sweep is made (reflectivity and velocity data are collected together).
www.srh.noaa.gov /srh/sod/radar/radinfo/radinfo.html   (2889 words)

 HOW IS THE REFLECTIVITY GRADIENT IMPORTANT TO SEVERE WEATHER?   (Site not responding. Last check: 2007-10-22)
If the reflectivity changes significantly over a small distance then that would be a strong reflectivity gradient.
The green colors represent light reflectivity (light rain aloft), the yellow colors are more of a moderate reflectivity (moderate rain aloft) and the red colors represent heavy reflectivity (heavy rain and possible hail aloft).
An example of a strong reflectivity gradient is a red color next to no reflectivity while an example of weak reflectivity would be a gradual transition from green to yellow colors.
www.theweatherprediction.com /habyhints2/381   (298 words)

 surf.ameslab.gov - Reflectivity   (Site not responding. Last check: 2007-10-22)
Two modes of scattering, reflectivity and grazing incidence diffraction (GID) are used in the investigation of interfaces.
In the reflectivity mode, the incident beam is specularily reflected as shown:
From the reflectivity, the neutron scattering length density or electron density (X-rays) can be determined and correlated with the structure at the interface.
www.reflec.ameslab.gov /aboutus/reflectivity.html   (106 words)

 Careers at Reflectivity   (Site not responding. Last check: 2007-10-22)
The work environment at Reflectivity is both very demanding and very rewarding.
As the senior representative of the company in Asia, the ASD will be responsible for meeting revenue targets, design wins, product introductions, key account management, sales channel establishment and management, regional technical support, PR, and maintaining the integrity of Reflectivity, Inc. at the highest levels.
Reflectivity is in the early stages of design-in with front projector OEMs.
www.reflectivity.com /career.html   (2337 words)

 IHOP Modeling: Subjective Evaluation of Model Runs   (Site not responding. Last check: 2007-10-22)
There is a line of storms as in the model forecast, but there are also individual strong cells (some supercells) over eastern CO, the strongest near LIC, but others over se CO into extreme se KS that are NOT in the model forecast.
Model has the strong and expanding bow-echo just passing the southern OK border, with a shape very much like observed reflectivity but, as was the case at 03z, is too slow compared to reality.
First signs of this in reflectivity loop are sct cells nnw-sse in wctl NE beginning 08-09z, with a well-defined sharp line nnw-sse in wctl NE by 11z extending south to a few cells in a line into KS.
laps.fsl.noaa.gov /szoke/IHOP/ihopmodeleval.html   (5369 words)

 MEASURING REFLECTIVITY OF SECONDARY MIRRORS   (Site not responding. Last check: 2007-10-22)
The values recorded with the mirror in place were, of course, lower than those obtained without the mirror.
The ratio of the two is the reflectivity of the mirror.
The Tel-Poke mirror was measured before and after cleaning, and showed a significant decrease in reflectivity when the mirror was dirty.
www.prairieastronomyclub.org /reflect.htm   (434 words)

 Multilayer Reflectivity   (Site not responding. Last check: 2007-10-22)
The reflectivity is calculated using the Fresnel equations and the analytic formula given by V. Kohn in Phys.
Interdiffusion/roughness is modeled using the Nevot-Croce factor which multiplies the reflection coefficient of each interface.
This assumes an error function profile for the interface with the specified rms thickness.
www-cxro.lbl.gov /optical_constants/multi2.html   (211 words)

 NCDC: NEXRAD National Mosaic Reflectivity Images
Remember, this packet may be one of several contained in one record within the data file.
Starting data location depends on length of the reflectivity field, stop location depends on length of the velocity field.
Starting data location depends on length of the reflectivity and velocity fields, stop location depends on length of the spectrum width field.
lwf.ncdc.noaa.gov /oa/radar/leveliidoc.html   (2531 words)

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