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Topic: Diffuse sky radiation


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In the News (Mon 27 May 19)

  
  Sky - Biocrawler   (Site not responding. Last check: 2007-10-08)
The sky is often defined as the place a person sees when he or she looks up from the earth.
In the night sky (and to some extent during the day) the Moon, planets and stars are visible in the sky.
Similarly, because the blue hue of the sky during daytime is such a universally observed and understood phenomenon, people say "as sure as the sky is blue" to mean that something is an indisputable fact.
www.biocrawler.com /encyclopedia/Sky   (639 words)

  
 Solar Radiation Data Manual for Buildings
To simplify the analysis, and because diffuse radiation from the horizon is a small part of the total radiation, it is treated in the same manner as isotropic sky and ground-reflected diffuse radiation.
Second, the isotropic diffuse sky radiation were reduced to account for the reduced field of view of the sky because of the roof overhang.
The transmitted isotropic diffuse sky radiation was reduced to account for the reduced field of view of the sky because of the roof overhang.
rredc.nrel.gov /solar/pubs/bluebook/appendix.html   (3197 words)

  
 AccuWeather.com Weather Glossary
Downward scattered and reflected solar radiation, coming from the whole hemisphere with the exception of the solid angle of the sun's disc on a surface perpendicular to the axis of this cone.
Equality of radiation is indicated by the balance of the differential thermometer.
Radiation coming from the solid angle of the sun's disc, as opposed to diffuse sky radiation, effective terrestrial radiation, or radiation from any other source.
wwwa.accuweather.com /adcbin/public/wxglossary.asp?type=d   (1091 words)

  
 Aerospace Science and Technology Dictionary D Page
Radiant energy propagating in many different directions through a given small volume of space; to be contrasted with parallel radiation.
The absolute value of the ratio of the molecular flux per unit area to the concentration gradient of a gas diffusing through a gas or a porous medium where the molecular flux is evaluated across a surface perpendicular to the direction of the concentration gradient.
The diffusivity has dimensions of a length times a velocity; it varies with the property diffused, and for any given property it may be considered a constant or a function of temperature, space, etc., depending on the context.
www.hq.nasa.gov /office/hqlibrary/aerospacedictionary/508/d.html   (9780 words)

  
 MODULE 1   (Site not responding. Last check: 2007-10-08)
The extraterrestrial radiation on top of the earth's surface depends on many factors such as the distance, orientation, etc. As the earth makes an elliptical orbit round the sun, there is approximately a 6.6% variation in the amount of solar radiation received on top of the earth's atmosphere throughout the year.
), and that the spectral transmittance of beam radiation (
The attenuation of solar radiation by the earth's atmosphere is summarized in Table 1.2.6 indicating the attenuation caused at different elevation, at different wavelengths and by the various constituents of the atmosphere.
www.courses.ait.ac.th /ED06.22/course1/lecs/module1/m12o98.html   (2245 words)

  
 The "extremely rare" procedure
Global radiation values larger than the extra-atmospheric irradiance can be measured in the tropics when scattered clouds pass near the sun.
Diffuse sky radiation can reach a relatively high value when the sky is overcast with highly transmitting cloud and the ground albedo is great.
The appearance of positive longwave net radiation is limited to the special case where a very warm cloud layer moves onto a surface which is kept cold.
bsrn.ethz.ch /wrmc/proc2.html   (602 words)

  
 Glossary / Index
radiation received on a plane surface i from a small solid angle centered on the sun's disk (a.k.a.
combined quantity of direct, diffuse sky, and diffuse reflected solar radiation received on a plane surface from a solid angle of 360°, integrated over all wavelengths (a.k.a.
ratio of the radiant flux reflected from a surface to the incident radiation (a.k.a.
baustudio.com /presents/Glossary.html   (1929 words)

  
 Review of Atmospheric Fundamentals
Incident radiation at these longer wavelengths (>310nm) is transmitted, or scattered and reflected The portion that is not reflected reaches the surface as direct + diffuse radiation.
Measured as transmittance, the ratio of the transmitted radiaition to the toal radiation incident upon the medium.
Since this scattered radiation is dispersed in all directions, some is sent back to space, the rest reaches the surface as diffuse (or sky) radiation, rich in blue.
windfall.evsc.virginia.edu /~jlm8h/class/fund1.html   (1311 words)

  
 Diffuse Nebulae
Diffuse nebulae, sometimes inacurately referred to as gaseous nebulae, are clouds of interstellar matter, namely thin but widespread agglomerations of gas and dust.
Diffuse emission nebulae are often called H II regions because they are mainly consisted of ionized hydrogene, H II - the roman number after the element symbol (here H) designating the ionization level: `I' would stand for neutral atoms, the `II' here means first ionization, i.e.
Diffuse nebulae were longly be considered as distant, unresolved star clusters or star clouds, until in the 1860s spectroscopy revealed their gaseous nature by showing line spectra, in particular due to the pioneering research of William Huggins.
www.seds.org /messier/diffuse.html   (547 words)

  
 UO SRML: Glossary "S"
Radiation that has been reflected from particles, disrupting the original direction of the beam.
Below is a picture of the sky dome at the Solar Radiation Research Laboratory taken by an all-sky camera.
Synonymous with diffuse sky radiation, the radiation component that strikes a point from the sky, excluding circumsolar radiation.
solardat.uoregon.edu /S.html   (924 words)

  
 Middleton Solar - reference page
Global Radiation - total solar radiation; the sum of direct, diffuse, and ground-reflected radiation; however, because ground reflected radiation is usually insignificant compared to direct and diffuse, for all practical purposes global radiation is said to be the sum of direct and diffuse radiation only.
Global (total) normal solar irradiance is all radiation that strikes a flat surface that faces the sun, while direct normal solar irradiance excludes all radiation that does not come from the direction of the sun in the sky.
Short-wave Radiation - the principal portion of the solar spectrum that spans from approximately 300 nanometres (nm) to 3000 nm in the electromagnetic spectrum.
www.middletonsolar.com /references   (1483 words)

  
 Pubs.GISS: Abstract of Lacis et al. 1998   (Site not responding. Last check: 2007-10-08)
Radiative transfer calculations that utilize the scalar approximation of light produce intensity errors as large as 10% in the case of pure Rayleigh scattering.
However, polarized light scattered from an underlying ocean surface, or from atmospheric aerosols, interacts with the pattern of Rayleigh scattered polarization to distort the error cancellation and thus incur larger flux and albedo errors.
While addition of scattered radiation from clouds, aerosols or ground surface into the Rayleigh atmosphere tends to reduce the magnitude of scalar approximation intensity errors, the scalar errors in fluxes and albedos are not proportionately reduced, but are actually increased.
pubs.giss.nasa.gov /abstracts/1998/LacisChowdharyM.html   (158 words)

  
 MODULE 1   (Site not responding. Last check: 2007-10-08)
Diffuse radiation : The solar radiation scattered by aerosols, dust and by Rayleigh mechanism.
It is principally a measure of the radiation that is transmitted through the atmosphere and is therefore dependent only on the extra terrestrial radiation and the radiation falling at the earth's surface.
To estimate the total solar radiation falling on tilted surfaces, it is necessary to know the directions of the beam and the diffuse component that reach the earth's surface.
www.courses.ait.ac.th /ED06.22/course1/lecs/module1/m13o98.html   (3954 words)

  
 The Poster Exhibit on Solar Radiation Data
The study of the solar radiation data can be extremely useful in establishing these more definitely and can lead to a more accurate and thorough understanding of the natural light phenomenon wherever it occurs.
It was these monthly normals that confirmed the observation made in the previous paper that June radiation is twice as strong as October radiation and therefore that October exposures needed to be twice as long as June exposures to accomplish the same result.
A general study of the solar radiation maps which demonstrate the dramatic changes of the solar patterns that sweep across the continent emphasizes the difficulty of depending on natural light for light bleaching and encourages the search for an effective artificial source that would be more constant and dependable for use in conservation.
aic.stanford.edu /sg/bpg/annual/v01/bp01-08.html   (857 words)

  
 Sky - Wikipedia, the free encyclopedia
The sky is (roughly) the part of the atmosphere or of outer space visible from the surface of the earth (or any other astronomical object; see Extraterrestrial skies).
Birds, insects, airplanes, and kites are often considered to fly in the sky.
During daylight the sky has the appearance of a deep blue surface, but this is the result of the air scattering sunlight.
en.wikipedia.org /wiki/Sky   (598 words)

  
 RReDC Glossary of Solar Radiation Resource Terms
Shortwave Radiation - the principal portion of the solar spectrum that spans from approximately 300 nanometers (nm) to 4000 nm in the electromagnetic spectrum.
Sky Dome - refers to the appearance of the entire sky, from horizon to zenith in all directions.
Sky Radiation - synonymous with diffuse sky radiation, the radiation component that strikes a point from the sky, excluding circumsolar radiation.
rredc.nrel.gov /solar/glossary/gloss_s.html   (1069 words)

  
 1.10 Spectral Characteristics of Solar Radiation
The incident solar radiation at the earth's surface is very different to that at the top of the atmosphere due to atmospheric effects, as shown in Figure 1.10.2, which compares the solar spectral irradiance at the earth's surface to fl body irradiance from a surface of temperature 5900
The solar spectral irradiance at the earth's surface is influenced by the atmospheric conditions and the zenith angle of the sun.
Beside the direct sunlight falling on a surface, there is another light source called sky radiation, diffuse radiation or skylight, which is produced by the scattering of the sunlight by atmospheric molecules and aerosols.
www.profc.udec.cl /~gabriel/tutoriales/rsnote/cp1/cp1-10.htm   (366 words)

  
 Annual Average Daily Solar Radiation on the Horizontal
The amount of solar radiation reaching the earth's surface varies greatly because of changing atmospheric conditions and the changing position of the sun, both during the day and throughout the year.
Clouds are the predominant atmospheric condition that determines the amount of solar radiation that reaches the earth.
At midday, the sun is positioned high in the sky and the path of the sun's rays through the earth's atmosphere is shortened.
www.thermomax.com /usdata.html   (551 words)

  
 RReDC Glossary of Solar Radiation Resource Terms   (Site not responding. Last check: 2007-10-08)
Diffuse Horizontal Irradiance - synonym for diffuse sky radiation.
Diffuse Sky Radiation - the radiation component that strikes a point from the sky, excluding circumsolar radiation.
In the absence of atmosphere, there should be almost no diffuse sky radiation.
rredc.nrel.gov /solar/glossary/gloss_d.html   (208 words)

  
 INDOEXPub30   (Site not responding. Last check: 2007-10-08)
This is a rough measure of the instrument sensitivity to diffuse sky radiation.
The plotted value is the ratio of the instrument response to sky radiation divided by the instrument response to the calibration lamp.
The diffuse calibration is somewhat sensitive to both solar zenith angle (because of forward scattering) and aerosol optical depth, which changes both the spectral and angular distribution of diffuse sky radiation.
www-indoex.ucsd.edu /publications/Version4.3.html   (7960 words)

  
 The Diffuse High-Energy Background - Introduction
This is the diffuse high-energy background: X-ray and gamma-ray light from all over the sky.
Scientists believe the radiation comes from outside our Milky Way Galaxy, since radiation from within the Galaxy would be brighter in some places and dimmer in others, due to our galaxy's shape.
Above 1 keV, most of the "diffuse" background is not truly diffuse in origin at all, but comes from many distant extragalactic objects.
imagine.gsfc.nasa.gov /docs/science/know_l1/diffuse_background.html   (1117 words)

  
 Diffuse sky radiation - Wikipedia, the free encyclopedia
Spectrum of blue sky clearly showing solar Fraunhofer lines and atmospheric water absorption band.
Scattering and absorption are major causes of the attenuation of radiation by the atmosphere.
There is essentially zero direct sunlight under an overcast sky, so all light is then diffuse sky radiation.
en.wikipedia.org /wiki/Diffuse_sky_radiation   (982 words)

  
 da Himmel The sky is often defined as the...   (Site not responding. Last check: 2007-10-08)
The concept of the "sky", as it is applied here on Earth, can be generalized to mean the space seen when one looks upward from the surface of any planet planet (see Skies of other planets Skies of other planets).
The sky is also sometimes defined as the denser gas gaseous zone of a planet's atmosphere atmosphere.
In the field of astronomy astronomy, the sky is also called the celestial sphere celestial sphere.
www.biodatabase.de /Sky   (562 words)

  
 AWI: Surface Radiation Measurements
Since 31 July 1992 surface radiation measurements have been carried out at Koldewey in the framework of the Baseline Surface Radiation Network (BSRN) in cooperation with the Norsk Polarinstitutt.
The radiation signals are taken in one minute intervals and stored as averages over 5 minutes.
At AWI, the radiation measurements - averaged over 5 minutes - are archived together with the data from the mast measurements, daily upper air soundings and routine synoptic surface observations in a relational database (SYBASE).
www.awi-bremerhaven.de /MET/NyAlesund/radiation.html   (255 words)

  
 AWI: Surface Radiation Measurements
In March 1992 the radiation measurements at Neumayer were extended in order to fulfil the standards of the Baseline Surface Radiation Network (BSRN).
At AWI, the radiation measurements - averaged over 10 (5) minutes - are archived together with the data from the mast measurements, daily upper air soundings and routine synoptic surface observations in a relational database (SYBASE).
Measurements for the global and refleced short-wave radiation fluxes as well as for the incomming and outgoing long-wave components are available from March 13 1982.
www.awi-bremerhaven.de /MET/Neumayer/radiation.html   (367 words)

  
 System test laboratory   (Site not responding. Last check: 2007-10-08)
The diffuse sky radiation is measured by an Eppley PSP used with an Eppley Shadow Band Stand which shields the sensing element of the pyranometer from direct solar radiation with an anodized aluminum band approximately 25 inches in diameter and 3 inches wide.
Infrared radiation is measured with a pyrgeometer, the Eppley Precision Infrared Radiometer (PIR).
A pyrgeometer measures the exchange of radiation between a horizontal flened surface (the detector) and the target viewed (the sky).
www.fsec.ucf.edu /solar/capabils/syslab/syslab.htm   (820 words)

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