GC: n
CT: Solar radiation is radiant energy emitted by the sun, particularly electromagnetic energy. About half of the radiation is in the visible short-wave part of the electromagnetic spectrum.
The other half is mostly in the near-infrared part, with some in the ultraviolet part of the spectrum.
The portion of this ultraviolet radiation that is not absorbed by the atmosphere produces a suntan or a sunburn on people who have been in sunlight for extended periods of time.
S: http://www.sciencedaily.com/articles/s/solar_radiation.htm (last access: 26 January 2015)
N: 1. solar (adj): mid-15c., “pertaining to the sun,” from Latin solaris “of the sun,” from sol “sun”. Meaning “living room on an upper story” is from Old English, from Latin solarium. Old English had sunlic “solar.”
radiation (n): mid-15c., “act or process of radiating,” from Middle French radiation and directly from Latin radiationem (nominative radiatio) “a shining, radiation,” noun of action from past participle stem of radiare “to beam, shine, gleam; make beaming,” from radius “beam of light; spoke of a wheel” (see radius). Meaning “rays or beams emitted” is from 1560s. Meaning “divergence from a center” is 1650s.
2. Solar radiation is the radiation, or energy we get from the sun. It is also known as short-wave radiation. Solar radiation comes in many forms, such as visible light, radio waves, heat (infrared), x-rays, and ultraviolet rays. Measurements for solar radiation are higher on clear, sunny day and usually low on cloudy days. When the sun is down, or there are heavy clouds blocking the sun, solar radiation is measured at zero.
3. In PV system design it is essential to know the amount of sunlight available at a particular location at a given time. The two common methods which characterise solar radiation are the solar radiance (or radiation) and solar insolation. The solar radiance is an instantaneous power density in units of kW/m2. The solar radiance varies throughout the day from 0 kW/m2 at night to a maximum of about 1 kW/m2. The solar radiance is strongly dependant on location and local weather. Solar radiance measurements consist of global and/or direct radiation measurements taken periodically throughout the day. The measurements are taken using either a pyranometer (measuring global radiation) and/or a pyrheliometer (measuring direct radiation). In well established locations, this data has been collected for more than twenty years.
4. An alternative method of measuring solar radiation, which is less accurate but also less expensive, is using a sunshine recorder. These sunshine recorders (also known as Campbell-Stokes recorders), measure the number of hours in the day during which the sunshine is above a certain level (typically 200 mW/cm2). Data collected in this way can be used to determine the solar insolation by comparing the measured number of sunshine hours to those based on calculations and including several correction factors.
5. A final method to estimate solar insolation is cloud cover data taken from existing satellite images.
6. While solar irradiance is most commonly measured, a more common form of radiation data used in system design is the solar insolation. The solar insolation is the total amount of solar energy received at a particular location during a specified time period, often in units of kWh/(m2 day). While the units of solar insolation and solar irradiance are both a power density (for solar insolation the “hours” in the numerator are a time measurement as is the “day” in the denominator), solar insolation is quite different than the solar irradiance as the solar insolation is the instantaneous solar irradiance averaged over a given time period. Solar insolation data is commonly used for simple PV system design while solar radiance is used in more complicated PV system performance which calculates the system performance at each point in the day. Solar insolation can also be expressed in units of MJ/m2 per year and other units and conversions are given in the units page.
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=solar+radiation&searchmode=none (last access: 26 January 2015). 2. http://www.mymobilebay.com/stationdata/whatissolarrad.htm (last access: 13 February 2015). 3 to 6. http://pveducation.org/pvcdrom/properties-of-sunlight/measurement-of-solar-radiation (last access: 13 February 2015).
SYN: solar rays, sun radiation.
S: TERMIUM PLUS (last access: 13 February 2015)
CR: bioconversion , solar energy, solar irradiance, ultraviolet radiation.
