Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Solar Radiation shopping experience:
1. Compare - without doubt the biggest advantage that the Solar Radiation offers shoppers today is the ability to compare thousands of Solar Radiation at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Solar Radiation? Wrong! If the Solar Radiation is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Solar Radiation then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Solar Radiation? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Solar Radiation and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Solar Radiation wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Solar Radiation then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Solar Radiation site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Solar Radiation, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Solar Radiation, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
Solar radiation is
radiant energy emitted by the sun from a
nuclear fusion reaction that creates electromagnetic energy. The
spectrum of solar radiation is close to that of a
black body with a temperature of about 5800 K. About half of the radiation is in the
light 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. http://www.grida.no/climate/ipcc_tar/wg1/041.htm#121 When ultraviolet radiation is not absorbed by the atmosphere or other protective coating, it can cause a change in the
Pigment#Biological_pigments of humans.
Solar radiation is commonly measured with a pyranometer or pyrheliometer.
Solar constant
The solar constant is the amount of incoming solar
electromagnetic radiation per unit area, measured on the outer surface of
Earth's atmosphere, in a plane perpendicular to the rays. The solar constant includes all types of solar radiation, not just the visible light. It is measured by satellite to be roughly 1366 watts per square metre, though it fluctuates by about 6.9% during a year - from 1412 W/m2 in early January to 1321 W/m2 in early July, due to the earth's varying distance from the sun, and by a few parts per thousand from day to day. Thus, for the whole Earth, with a
cross section (geometry) of 127,400,000 km², the power is
orders of magnitude (power) watt, plus or minus 3.5%. The solar constant is not quite constant over long time periods either; see
solar variation. The value 1366 W/m2 is equivalent to 1.96 calories per minute per square centimeter, which can also be expressed as 1.96
langley (unit) (or Ly) per minute.
The Earth receives a total amount of radiation determined by its
Cross section (geometry) (π R2), but as the planet rotates this energy is distributed across the entire surface area (4 π R2). Hence, the average incoming solar radiation (called sometimes the solar irradiance), taking into account the half of the planet not receiving any solar radiation at all, is one fourth the solar constant or ~342 W/m². At any given location and time, the amount received at the surface depends on the state of the atmosphere and the latitude.
The solar constant includes all wavelengths of solar electromagnetic radiation, not just the visible light. (See electromagnetic spectrum for more details) It is linked to the apparent magnitude of the Sun, −26.8, in that the solar constant and the magnitude of the sun are two methods of describing the apparent brightness of the Sun, though the magnitude only measures the visual output of the Sun.
In 1884
Samuel Pierpont Langley attempted to estimate the solar constant from
Mount Whitney in California, and (by taking readings at different times of day) attempted to remove atmospheric absorption effects. However he obtained the incorrect value of 2903 W/m2, perhaps due to mathematical errors. Between 1902 and 1957, measurements by
Charles Greeley Abbot and others at various high-altitude sites found values between 1322 and 1465 W/m2. Abbott proved that one of Langley's corrections was erroneously applied, and his results varied between 1.89 and 2.22 calories (1318 to 1548 W/m2), and the variation appeared to be solar, not terrestrial.
The
angular diameter of Earth seen from the sun is ca. 1/11,000 radian, so the solid angle of Earth seen from the sun is ca. 1/140,000,000
steradian. Thus, the sun emits about 2 billion times the amount of radiation that is caught by Earth, or about 3.86×1026 watts. The Sun at nine planets.org
Climate effect of solar radiation
On Earth, solar radiation is obvious as daylight when the sun is above the
horizon. This is during daytime, and also in summer near the poles at night, but not at all in winter near the poles. When the direct radiation is not blocked by clouds, it is experienced as
sunlight, a combination of bright yellow light (sunlight in the strict sense) and heat. The heat on the body, on objects, etc., that is directly produced by the radiation should be distinguished from the increase in air temperature.
The amount of radiation intercepted by a planetary body varies as the square of the distance between the star and the planet. The Earth's
orbit and
obliquity change with time (over thousands of years), sometimes forming a nearly perfect circle, and at other times stretching out to an
orbital eccentricity of 5% (currently 1.67%). The total insolation remains almost constant but the seasonal and latitudinal distribution and intensity of solar radiation received at the Earth's surface also varies Graph of variation of seasonal and latitudinal distribution of solar radiation. For example, at latitudes of 65 degrees the change in solar energy in summer & winter can vary by more than 25% as a result of the Earth's orbital variation. Because changes in winter and summer tend to offset, the change in the annual average insolation at any given location is near zero, but the redistribution of energy between summer and winter does strongly affect the intensity of seasonal cycles. Such changes associated with the redistribution of solar energy are considered a likely cause for the coming and going of recent
ice ages (see:
Milankovitch cycles).
Notes
See also
- Insolation: a measure of solar radiation energy incident on a surface
- Solar heating: Predicting solar heating effects
- Solar neutrino problem: solar neutrino measurement problem
- Solar variation: variations in solar activity
- Solar wind: particles flowing from the Sun
- Coronal mass ejection: large ejection of electrons and protons
- Polar aurora: usually electrons hitting Earth's atmosphere
- Solar flare: eruption creates increase of solar wind particles
- Solar proton event: protons hitting Earth's atmosphere
- Pyranometer: solar radiation sensor
External links
- Solar radiation - Encyclopedia of Earth
- Total solar irradiance data archive 1978-2007 at the website of the National Geophysical Data Center
- A Comparison of Methods for Providing Solar Radiation Data to Crop Models and Decision Support Systems, Rivington et al.
- Evaluation of three model estimations of solar radiation at 24 UK stations, Rivington et al.
- High resolution spectrum of solar radiation from Observatoire de Paris
- Measuring Solar Radiation : A lesson plan from the National Science Digital Library.
- Websurf astronomical information : Online tools for calculating Rising and setting times of Sun, Moon or planet, Azimuth of Sun, Moon or planet at rising and setting, Altitude and azimuth of Sun, Moon or planet for a given date or range of dates, and more.
- Daylength - Formulas to calculate the daylength depending from latitude and day of year.
- An Excel workbook with a solar position and solar radiation time-series calculator; by Greg Pelletier
- DOE information about the ASTM standard solar spectrum for PV evaluation.
- ASTM Standard for solar spectrum at ground level in the US (latitude ~ 37 degrees).
Solar radiation is radiant energy emitted by the sun from a
nuclear fusion reaction that creates electromagnetic energy. The spectrum of solar radiation is close to that of a
black body with a temperature of about 5800 K. About half of the radiation is in the light 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. http://www.grida.no/climate/ipcc_tar/wg1/041.htm#121 When ultraviolet radiation is not absorbed by the atmosphere or other protective coating, it can cause a change in the
Pigment#Biological_pigments of humans.
Solar radiation is commonly measured with a pyranometer or pyrheliometer.
Solar constant
The solar constant is the amount of incoming solar electromagnetic radiation per unit area, measured on the outer surface of Earth's atmosphere, in a plane perpendicular to the rays. The solar constant includes all types of solar radiation, not just the
visible light. It is measured by satellite to be roughly 1366 watts per square metre, though it fluctuates by about 6.9% during a year - from 1412 W/m2 in early January to 1321 W/m2 in early July, due to the earth's varying distance from the sun, and by a few parts per thousand from day to day. Thus, for the whole Earth, with a
cross section (geometry) of 127,400,000 km², the power is orders of magnitude (power)
watt, plus or minus 3.5%. The solar constant is not quite constant over long time periods either; see solar variation. The value 1366 W/m2 is equivalent to 1.96 calories per minute per square centimeter, which can also be expressed as 1.96 langley (unit) (or Ly) per minute.
The Earth receives a total amount of radiation determined by its Cross section (geometry) (π R2), but as the planet rotates this energy is distributed across the entire
surface area (4 π R2). Hence, the average incoming solar radiation (called sometimes the solar irradiance), taking into account the half of the planet not receiving any solar radiation at all, is one fourth the solar constant or ~342 W/m². At any given location and time, the amount received at the surface depends on the state of the atmosphere and the latitude.
The solar constant includes all wavelengths of solar electromagnetic radiation, not just the visible light. (See electromagnetic spectrum for more details) It is linked to the apparent magnitude of the Sun, −26.8, in that the solar constant and the magnitude of the sun are two methods of describing the apparent brightness of the Sun, though the magnitude only measures the visual output of the Sun.
In 1884 Samuel Pierpont Langley attempted to estimate the solar constant from Mount Whitney in California, and (by taking readings at different times of day) attempted to remove atmospheric absorption effects. However he obtained the incorrect value of 2903 W/m2, perhaps due to mathematical errors. Between 1902 and 1957, measurements by
Charles Greeley Abbot and others at various high-altitude sites found values between 1322 and 1465 W/m2. Abbott proved that one of Langley's corrections was erroneously applied, and his results varied between 1.89 and 2.22 calories (1318 to 1548 W/m2), and the variation appeared to be solar, not terrestrial.
The angular diameter of Earth seen from the sun is ca. 1/11,000
radian, so the solid angle of Earth seen from the sun is ca. 1/140,000,000
steradian. Thus, the sun emits about 2 billion times the amount of radiation that is caught by Earth, or about 3.86×1026 watts. The Sun at nine planets.org
Climate effect of solar radiation
On Earth, solar radiation is obvious as daylight when the sun is above the
horizon. This is during daytime, and also in summer near the poles at night, but not at all in winter near the poles. When the direct radiation is not blocked by clouds, it is experienced as
sunlight, a combination of bright yellow light (sunlight in the strict sense) and heat. The heat on the body, on objects, etc., that is directly produced by the radiation should be distinguished from the increase in
air temperature.
The amount of radiation intercepted by a planetary body varies as the square of the distance between the star and the planet. The Earth's
orbit and
obliquity change with time (over thousands of years), sometimes forming a nearly perfect circle, and at other times stretching out to an orbital eccentricity of 5% (currently 1.67%). The total
insolation remains almost constant but the seasonal and latitudinal distribution and intensity of solar radiation received at the Earth's surface also varies Graph of variation of seasonal and latitudinal distribution of solar radiation. For example, at latitudes of 65 degrees the change in solar energy in summer & winter can vary by more than 25% as a result of the Earth's orbital variation. Because changes in winter and summer tend to offset, the change in the annual average insolation at any given location is near zero, but the redistribution of energy between summer and winter does strongly affect the intensity of seasonal cycles. Such changes associated with the redistribution of solar energy are considered a likely cause for the coming and going of recent
ice ages (see:
Milankovitch cycles).
Notes
See also
- Insolation: a measure of solar radiation energy incident on a surface
- Solar heating: Predicting solar heating effects
- Solar neutrino problem: solar neutrino measurement problem
- Solar variation: variations in solar activity
- Solar wind: particles flowing from the Sun
- Coronal mass ejection: large ejection of electrons and protons
- Polar aurora: usually electrons hitting Earth's atmosphere
- Solar flare: eruption creates increase of solar wind particles
- Solar proton event: protons hitting Earth's atmosphere
- Pyranometer: solar radiation sensor
External links
- Solar radiation - Encyclopedia of Earth
- Total solar irradiance data archive 1978-2007 at the website of the National Geophysical Data Center
- A Comparison of Methods for Providing Solar Radiation Data to Crop Models and Decision Support Systems, Rivington et al.
- Evaluation of three model estimations of solar radiation at 24 UK stations, Rivington et al.
- High resolution spectrum of solar radiation from Observatoire de Paris
- Measuring Solar Radiation : A lesson plan from the National Science Digital Library.
- Websurf astronomical information : Online tools for calculating Rising and setting times of Sun, Moon or planet, Azimuth of Sun, Moon or planet at rising and setting, Altitude and azimuth of Sun, Moon or planet for a given date or range of dates, and more.
- Daylength - Formulas to calculate the daylength depending from latitude and day of year.
- An Excel workbook with a solar position and solar radiation time-series calculator; by Greg Pelletier
- DOE information about the ASTM standard solar spectrum for PV evaluation.
- ASTM Standard for solar spectrum at ground level in the US (latitude ~ 37 degrees).
Solar radiation - Wikipedia, the free encyclopedia
Solar radiation is radiant energy emitted by a sun as a result of its nuclear fusion reactions. The spectrum of the Sun's solar radiation is close to that of a black body with a ...
Solar Radiation Resource Information
Resource offering data archives, models, calculators and scientific reports.
Warm - solar radiation
ECN Sites. Solar Radiation . We are now going to study the solar radiation readings taken at the ECN sites on the 21st January 1998. Solar radiation is the radiation the earth ...
BBC NEWS | Africa | Using the sun to sterilise water
Solar radiation means a combination of ultra-violet rays and heat destroys the bacteria which cause common water-borne diseases like cholera, typhoid, dysentery and diarrhoea.
Solar Radiation
Ultraviolet Radiation is a form of radiant energy that is part of the Electromagnetic Spectrum.Electromagnetic Radiation can best be described in terms of a stream of mass-less ...
NREL: Solar Radiation Research Home Page
NREL's solar radiation research supports industry, government, and academia by providing solar radiation measurements, models, maps, and support services.
U.S. Solar Radiation Resource Maps
U.S. Solar Radiation Resource Maps: Atlas for the Solar Radiation Data Manual for ... These maps show the general trends in the amount of solar radiation received in the ...
Solar radiation - Encyclopedia of Earth
Almost all of the energy that drives the various systems (climate systems, ecosystems, hydrologic systems, etc.) found on the Earth originates from the sun (Figure 1).
JD & Sun - Solar Power Water Heating Systems & Installation - Free ...
For more than 30 years The Meteorological Office has been recording solar radiation in the UK. Look at the map, it shows an annual average of solar irradiation on a suitable house ...
Solar radiation and a delta-sigma ADC (Gadget Freak)
A device to measure the rays all around us, but it doesn't come under the 'tin-foil helmet' category. File it under delta-sigma ADC - it is a very detailed Solar Server project to ...
