Sunlight
hideSunlight, in the broad sense, is the total spectrum of the electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon. Near the poles in summer, the days are longer and the nights are shorter or non-existent. In the winter at the poles the nights are longer and for some periods of time, sunlight may not occur at all. When the direct radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and heat. Radiant heat directly produced by the radiation of the sun is different from the increase in atmospheric temperature due to the radiative heating of the atmosphere by the sun's radiation. Sunlight may be recorded using a sunshine recorder, pyranometer or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth. The World Meteorological Organization defines sunshine as direct irradiance from the Sun measured on the ground of at least 120 watts per square metre.
Direct sunlight has a luminous efficacy of about 93 lumens per watt of radiant flux, which includes infrared, visible, and ultra-violet light. Bright sunlight provides luminance of approximately 100,000 candela per square meter at the Earth's surface.
Sunlight is a key factor in photosynthesis, a process crucially important for life on Earth.
For more information about Sunlight, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with solar radiation
Supervolcano eruption -- in Sumatra -- deforested India 73,000 years ago
Space & Earth / Earth Sciences
Nov 23, 2009 |
4.5 / 5 (17) |
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A new study provides "incontrovertible evidence" that the volcanic super-eruption of Toba on the island of Sumatra about 73,000 years ago deforested much of central India, some 3,000 miles from the epicenter, ...
Experts: Failure to focus on farming will undermine global climate agreement and increase hunger
Nov 18, 2009 |
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Alarmed by a substantial oversight in the global climate talks leading up to the United Nations Climate Change Conference in Copenhagen next month, more than 60 of the world's most prominent agricultural scientists and leaders ...
Hidden Territory on Mercury Revealed
Space & Earth / Space Exploration
Nov 04, 2009 |
4.8 / 5 (20) |
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The MESSENGER spacecraft's third flyby of the planet Mercury has given scientists, for the first time, an almost complete view of the planet's surface and revealed some dramatic changes in Mercury's comet-like ...
Climate models don't tell the full story
Space & Earth / Earth Sciences
Oct 08, 2009 |
4 / 5 (10) |
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(PhysOrg.com) -- Climate models that predict heavy rainfall don’t give the whole picture, according to the results of a study by NWO (Netherlands Organisation for Scientific Research) scientist Martin Ziegler. He examined ...
Do dust particles curb climate change?
Space & Earth / Earth Sciences
Oct 06, 2009 |
4.6 / 5 (5) |
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(PhysOrg.com) -- A knowledge gap exists in the area of climate research: for decades, scientists have been asking themselves whether, and to what extent man-made aerosols, that is, dust particles suspended ...
Corals 'could starve in high CO2'
Oct 05, 2009 |
2 / 5 (4) |
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(PhysOrg.com) -- As human activity pumps more and more carbon into the atmosphere, a new threat has emerged to the world's coral reefs - starvation.
Forests of Artificial Trees Could Slow Global Warming
Aug 28, 2009 |
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(PhysOrg.com) -- A new study on how technology could help to regulate climate change has studied hundreds of ideas, and selected three considered practical and able to be implemented quickly. The report's ...
Long debate ended over cause, demise of ice ages -- may also help predict future
Space & Earth / Earth Sciences
Aug 06, 2009 |
4.4 / 5 (23) |
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Researchers have largely put to rest a long debate on the underlying mechanism that has caused periodic ice ages on Earth for the past 2.5 million years - they are ultimately linked to slight shifts in solar radiation caused ...
Galactic Colonization Limited By The Inability To Expand Exponentially
Jun 23, 2009 |
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(PhysOrg.com) -- For more than 50 years, many have taken the so-called Fermi Paradox to indicate that the existence of intelligent alien civilizations is an impossibility. However, a recent re-examination ...
Fake Astronaut Gets Hit by Artificial Solar Flare
Space & Earth / Space Exploration
Jun 04, 2009 |
4.3 / 5 (3) |
2
(PhysOrg.com) -- In 1972, Apollo astronauts narrowly escaped a potential catastrophe. On August 2nd of that year, a large and angry sunspot appeared and began to erupt, over and over again for more than a ...
Critical turning point can trigger abrupt climate change
Space & Earth / Earth Sciences
Apr 20, 2009 |
4.6 / 5 (58) |
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Ice ages are the greatest natural climate changes in recent geological times. Their rise and fall are caused by slight changes in the Earth's orbit around the Sun due to the influence of the other planets. But we do not know ...
Climate Change and Atmospheric Circulation Will Make for Uneven Ozone Recovery
Space & Earth / Earth Sciences
Apr 10, 2009 |
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(PhysOrg.com) -- Earth's ozone layer should eventually recover from the unintended destruction brought on by the use of chlorofluorocarbons (CFCs) and similar ozone-depleting chemicals in the 20th century. ...
Scorpion biodiversity
Apr 09, 2009 |
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Scorpions possess resistance to high temperatures and the ability to conserve water for long periods of time, and as a result thrive in hot and arid parts of the world. But is this global distribution also seen at a more ...
Growing Population Warming East African Nights?
Space & Earth / Earth Sciences
Mar 31, 2009 |
3.3 / 5 (7) |
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Nights are getting hotter in Nairobi and other inland cities as growing populations change sensitive local weather patterns, according to research at The University of Alabama in Huntsville.
'Master regulator' of skin formation discovered
Mar 24, 2009 |
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Researchers at Oregon State University have found one gene in the human body that appears to be a master regulator for skin development, in research that could help address everything from skin diseases such as eczema or ...
