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82-450: Sky blue refers to a collection of shades comparable to that of a clear daytime sky. Typically it is a shade of cyan or light teal , though some iterations are closer to light blue . The term (as "sky blew") is attested from 1681. A 1585 translation of Nicolas de Nicolay 's 1576 Les navigations, peregrinations et voyages faicts en la Turquie includes "the tulbant [turban] of the merchant must be skie coloured ". Displayed at right
164-467: A luminous efficacy of about 93 lumens per watt of radiant flux . This is higher than the efficacy (of source) of artificial lighting other than LEDs , which means using sunlight for illumination heats up a room less than fluorescent or incandescent lighting. Multiplying the figure of 1,050 watts per square meter by 93 lumens per watt indicates that bright sunlight provides an illuminance of approximately 98,000 lux ( lumens per square meter) on
246-411: A broad range of wavelengths: X-rays , ultraviolet , visible light , infrared , and radio waves . Different depths in the photosphere have different temperatures, and this partially explains the deviations from a black-body spectrum. There is also a flux of gamma rays from the quiescent sun, obeying a power law between 0.5 and 2.6 TeV . Some gamma rays are caused by cosmic rays interacting with
328-523: A color name in English was in 1879. Further origins of the color name can be traced back to a dye produced from the cornflower ( Centaurea cyanus ). In most languages, 'cyan' is not a basic color term and it phenomenologically appears as a greenish vibrant hue of blue to most English speakers. Other English terms for this "borderline" hue region include blue green , aqua , turquoise , teal , and grue . The web color cyan shown at right
410-534: A colour dictionary published in 2005 that is widely popular in the Hispanophone realm. Displayed at right is the colour dark sky blue . This is the colour called sky blue in Pantone . The source of this colour is the "Pantone Textile Paper eXtended (TPX)" colour list, color #14-4318 TPX—Sky Blue. Cyan Cyan ( / ˈ s aɪ . ə n , - æ n / ) is the color between blue and green on
492-689: A colour name in English in 1920. At right is displayed the colour French sky blue , which is the tone of sky blue that is called sky blue ( bleu ciel ) in the Pourpre.com colour list, a colour list widely popular in France . Spanish sky blue is the colour that is called celeste (the Spanish word for "sky blue") in the Guía de coloraciones ( Guide to colourations ) by Rosa Gallego and Juan Carlos Sanz,
574-414: A good diffusion of light blue without saturation , which causes the prevalence of the white or of the warm colours of sunrise and sunset ; in these excellent conditions, it is possible to see Celeste and its variations perpendicularly to the sun , toward the horizon , where the sunlight is maximum as the sky is directly illuminated, and these shades merge with the golden light of solar rays and
656-429: A highly regarded precious gem. Turquoise comes in a variety of shades from green to blue, but cyan hues are particularly prevalent. Approximately 3,700 years ago, an intricately crafted dragon-shaped treasure made from over 2,000 pieces of turquoise and jade was created. This artifact is widely recognized as the oldest Chinese dragon totem by many Chinese scholars. Turquoise jewelry also held significant importance among
738-611: A less clear, and probably more complicated fashion, with Earth's climate responses than earlier assumed, fueling broad avenues of new research in "the connection of the Sun and stratosphere, troposphere, biosphere, ocean, and Earth's climate". The spectrum of surface illumination depends upon solar elevation due to atmospheric effects, with the blue spectral component dominating during twilight before and after sunrise and sunset, respectively, and red dominating during sunrise and sunset. These effects are apparent in natural light photography where
820-428: A nearly perfect circle, and at other times stretching out to an orbital eccentricity of 5% (currently 1.67%). As the orbital eccentricity changes, the average distance from the Sun (the semimajor axis does not significantly vary, and so the total insolation over a year remains almost constant due to Kepler's second law , where A {\displaystyle A} is the "areal velocity" invariant. That is,
902-463: A number of states in the world. For many people with light skin, one purpose for sunbathing is to darken one's skin color (get a sun tan), as this is considered in some cultures to be attractive, associated with outdoor activity, vacations/holidays , and health. Some people prefer naked sunbathing so that an "all-over" or "even" tan can be obtained, sometimes as part of a specific lifestyle. Controlled heliotherapy , or sunbathing, has been used as
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#1732793384073984-580: A perpendicular surface at sea level. The illumination of a horizontal surface will be considerably less than this if the Sun is not very high in the sky. Averaged over a day, the highest amount of sunlight on a horizontal surface occurs in January at the South Pole (see insolation ). Dividing the irradiance of 1,050 W/m by the size of the Sun's disk in steradians gives an average radiance of 15.4 MW per square metre per steradian. (However,
1066-494: A printed page. To reproduce the web color cyan in inks, it is necessary to add some white ink to the printer's cyan below, so when it is reproduced in printing, it is not a primary subtractive color. It is called aqua (a name in use since 1598) because it is a color commonly associated with water , such as the appearance of the water at a tropical beach. Cyan is also one of the common inks used in four-color printing , along with magenta , yellow , and black ; this set of colors
1148-537: A risk factor for skin cancer, "sun avoidance may carry more of a cost than benefit for over-all good health". A study found that there is no evidence that UV reduces lifespan in contrast to other risk factors like smoking, alcohol and high blood pressure. Elevated solar UV -B doses increase the frequency of DNA recombination in Arabidopsis thaliana and tobacco ( Nicotiana tabacum ) plants. These increases are accompanied by strong induction of an enzyme with
1230-457: A tint being a cyan mixed with white, and a shade being mixed with black. Color nomenclature is subjective. Many shades of cyan with a bluish hue are called blue. Similarly, those with a greenish hue are referred to as green. A cyan with a dark shade is commonly known as teal . A teal blue shade leans toward the blue end of the spectrum. Variations of teal with a greener tint are commonly referred to as teal green . Turquoise , reminiscent of
1312-479: A treatment for psoriasis and other maladies. Skin tanning is achieved by an increase in the dark pigment inside skin cells called melanocytes , and is an automatic response mechanism of the body to sufficient exposure to ultraviolet radiation from the Sun or from artificial sunlamps. Thus, the tan gradually disappears with time, when one is no longer exposed to these sources. The ultraviolet radiation in sunlight has both positive and negative health effects, as it
1394-561: Is a secondary color in the RGB color model , which uses combinations of red, green and blue light to create all the colors on computer and television displays. In X11 colors , this color is called both cyan and aqua . In the HTML color list, this same color is called aqua. The web colors are more vivid than the cyan used in the CMYK color system, and the web colors cannot be accurately reproduced on
1476-490: Is a measure of flux density , is the amount of incoming solar electromagnetic radiation per unit area that would be incident on a plane perpendicular to the rays, at a distance of one astronomical unit (AU) (roughly the mean distance from the Sun to Earth). The "solar constant" includes all types of solar radiation, not just the visible light . Its average value was thought to be approximately 1,366 W/m , varying slightly with solar activity , but recent recalibrations of
1558-410: Is ample sunlight. Some common places for sunbathing include beaches , open air swimming pools , parks , gardens , and sidewalk cafes . Sunbathers typically wear limited amounts of clothing or some simply go nude . For some, an alternative to sunbathing is the use of a sunbed that generates ultraviolet light and can be used indoors regardless of weather conditions. Tanning beds have been banned in
1640-473: Is an azure - cyan colour associated with deep shade of sky blue. Deep sky blue is a web colour . This is the colour on the colour wheel ( RGB/HSV colour wheel ) halfway between azure and cyan. The colour name deep sky blue came into use with the formulization of the X11 colour names over 1985–1989. The normalized colour coordinates for deep sky blue are identical to Capri , which first came into use as
1722-437: Is both a principal source of vitamin D 3 and a mutagen . A dietary supplement can supply vitamin D without this mutagenic effect, but bypasses natural mechanisms that would prevent overdoses of vitamin D generated internally from sunlight. Vitamin D has a wide range of positive health effects, which include strengthening bones and possibly inhibiting the growth of some cancers. Sun exposure has also been associated with
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#17327933840731804-482: Is both a requisite for vitamin D 3 synthesis and a mutagen . Sunlight takes about 8.3 minutes to reach Earth from the surface of the Sun. A photon starting at the center of the Sun and changing direction every time it encounters a charged particle would take between 10,000 and 170,000 years to get to the surface. Sunlight is a key factor in photosynthesis , the process used by plants and other autotrophic organisms to convert light energy , normally from
1886-404: Is equal to 128×10 lux . The direct normal illuminance ( E dn ), corrected for the attenuating effects of the atmosphere is given by: where c is the atmospheric extinction and m is the relative optical airmass . The atmospheric extinction brings the number of lux down to around 100,000 lux. The total amount of energy received at ground level from the Sun at the zenith depends on
1968-569: Is fueled by light from the Sun. Most autotrophs , such as plants, use the energy of sunlight, combined with carbon dioxide and water, to produce simple sugars—a process known as photosynthesis . These sugars are then used as building-blocks and in other synthetic pathways that allow the organism to grow. Heterotrophs , such as animals, use light from the Sun indirectly by consuming the products of autotrophs, either by consuming autotrophs, by consuming their products, or by consuming other heterotrophs. The sugars and other molecular components produced by
2050-497: Is known as sora iro or mizuiro , referring to the colour of the sky or its reflection on the sea. The other one is also another conventional celeste ( HEX #99cbff and RGB 153,203,255) containing 100% of blue , associated to a more generic color of the sky and remembering a type of light zenithal blue and the next sky blue gradations. Celeste, that is, the pure Celeste strictly speaking ( HEX #B2FFFF; RGB 178,255,255) from here on (and which can be thought as
2132-466: Is needed; only a handful of objects in the Solar System have been discovered that are known to orbit farther than such a distance, among them 90377 Sedna and (87269) 2000 OO 67 . On Earth, the solar radiation varies with the angle of the Sun above the horizon , with longer sunlight duration at high latitudes during summer, varying to no sunlight at all in winter near the pertinent pole. When
2214-509: Is not blocked by clouds , it is experienced as sunshine , a combination of bright light and radiant heat (atmospheric). When blocked by clouds or reflected off other objects , sunlight is diffused . Sources estimate a global average of between 164 watts to 340 watts per square meter over a 24-hour day; this figure is estimated by NASA to be about a quarter of Earth's average total solar irradiance . The ultraviolet radiation in sunlight has both positive and negative health effects, as it
2296-487: Is one such commonly used pigment. A typical formulation of process cyan is shown in the color box on the right. Sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun , in particular infrared , visible , and ultraviolet light. On Earth , sunlight is scattered and filtered through Earth's atmosphere as daylight when the Sun is above the horizon . When direct solar radiation
2378-461: Is referred to as CMYK. In printing, the cyan ink is sometimes known as printer's cyan, process cyan, or process blue. While both the additive secondary and the subtractive primary are called cyan , they can be substantially different from one another. Cyan printing ink is typically more saturated than the RGB secondary cyan, depending on what RGB color space and ink are considered. That is, process cyan
2460-562: Is the web colour sky blue . Celeste ( Spanish: [θeˈleste, se-] , Italian: [tʃeˈlɛste] , English: / s ɪ ˈ l ɛ s t / ) is the colloquial name for the pale turquoise blue colour. The same word, meaning "of the sky", is used in Spanish , Portuguese and Italian for the colour. Etymologically , it is derived by Latin term caelestis , that means del cielo in Italian. There are two "conventional" colours denominated celeste, according to
2542-401: Is used, because in modern times Earth's perihelion , the closest approach to the Sun and, therefore, the maximum E ext occurs around January 3 each year. The value of 0.033412 is determined knowing that the ratio between the perihelion (0.98328989 AU) squared and the aphelion (1.01671033 AU) squared should be approximately 0.935338. The solar illuminance constant ( E sc ),
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2624-506: Is usually outside the RGB gamut , and there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there can be variations in the printed color that is pure cyan ink. This is because real-world subtractive (unlike additive) color mixing does not consistently produce the same result when mixing apparently identical colors, since the specific frequencies filtered out to produce that color affect how it interacts with other colors. Phthalocyanine blue
2706-588: The Aztecs , who often featured this precious gemstone in vibrant frescoes for both symbolic and decorative purposes. The Aztecs revered turquoise, associating its color with the heavens and sacredness. Additionally, ancient Egyptians interpreted cyan hues as representing faith and truth, while Tibetans viewed them as a symbol of infinity. After earlier uses in various contexts, cyan hues found increased use in diverse cultures due to their appealing aesthetic qualities in religious structures and art pieces. For example,
2788-555: The Earth's atmosphere spans a range of 100 nm to about 1 mm (1,000,000 nm). This band of significant radiation power can be divided into five regions in increasing order of wavelengths : Tables of direct solar radiation on various slopes from 0 to 60 degrees north latitude, in calories per square centimetre, issued in 1972 and published by Pacific Northwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Portland, Oregon, USA, appear on
2870-441: The color models . One is the pure Celeste , ( HEX #B2FFFF; RGB 178,255,255) which may be referred as the "true" celeste as it is traditionally or officially understood; in English , it may also be referred to as Italian sky blue (blu cielo italiano) and Bianchi Green , referring to Bianchi , the famous Italian company for bikes , the first in the history of vehicles, whose colour is characteristic. The Japanese equivalent
2952-415: The cyan is more intense. In the afternoon, it is the opposite and the pure celeste and similar gradations could be widely visible between the sun and horizon when the star is high, but starting to go down, that is especially in the early afternoon hours. Instead, in the cold season, with a low sun and sunlight , the pure celeste may be visible only at the horizon, where the cyan is more intense for
3034-533: The electromagnetic spectrum . Although the radiation created in the solar core consists mostly of x rays , internal absorption and thermalization convert these super-high-energy photons to lower-energy photons before they reach the Sun's surface and are emitted out into space. As a result, the photosphere of the Sun does not emit much X radiation ( solar X-rays ), although it does emit such "hard radiations" as X-rays and even gamma rays during solar flares . The quiet (non-flaring) Sun, including its corona , emits
3116-436: The visible spectrum of light . It is evoked by light with a predominant wavelength between 500 and 520 nm , between the wavelengths of green and blue. In the subtractive color system, or CMYK color model , which can be overlaid to produce all colors in paint and color printing, cyan is one of the primary colors , along with magenta and yellow . In the additive color system, or RGB color model , used to create all
3198-428: The white of the horizon, both in the morning and afternoon , or even across the entire region between the star and the horizon, when the star is high, relatively next to solar or true noon . In particular, in the warm seasons, with the inclination of a hemisphere with respect to the sun , there are simultaneously the optimization of sunlight , daylight hours , and so the pure celeste might be visible in
3280-426: The "true" or "conventional" celeste), is a gradation of the cyan and a cold color . It is the colour of the sky with optimal visibility , when it is clear, perfectly or near-perfectly cloudless and sunny with an optimal quantity of humidity , absence or optimal quantity of atmospheric dust , aerosol / particulates with a good or at least moderate AIQ (Air Quality Index), absence of mist , haze , resulting in
3362-423: The Sun, into chemical energy that can be used to synthesize carbohydrates and fuel the organisms' activities. Daylighting is the natural lighting of interior spaces by admitting sunlight. Solar irradiance is the solar energy available from sunlight. Researchers can measure the intensity of sunlight using a sunshine recorder , pyranometer , or pyrheliometer . To calculate the amount of sunlight reaching
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3444-475: The atmosphere) hitting the ground is around 1,120 W/m . In terms of energy, sunlight at Earth's surface is around 52 to 55 percent infrared (above 700 nm ), 42 to 43 percent visible (400 to 700 nm), and 3 to 5 percent ultraviolet (below 400 nm). At the top of the atmosphere, sunlight is about 30% more intense, having about 8% ultraviolet (UV), with most of the extra UV consisting of biologically damaging short-wave ultraviolet. Direct sunlight has
3526-415: The autotrophs are then broken down, releasing stored solar energy, and giving the heterotroph the energy required for survival. This process is known as cellular respiration . In prehistory , humans began to further extend this process by putting plant and animal materials to other uses. They used animal skins for warmth, for example, or wooden weapons to hunt. These skills allowed humans to harvest more of
3608-685: The blue because of the Raylegh scattering . Bleu celeste ("sky blue") is a rarely occurring tincture in heraldry (not being one of the seven main colours or metals or the three "staynard colours"). This tincture is sometimes also called ciel or simply celeste . It is depicted in a lighter shade than the range of shades of the more traditional tincture azure , which is the standard blue used in heraldry. The Italian Misplaced Pages cites Il dizionario dei colori: nomi e valori in quadricromia by S.Fantetti and C.Petracchi and describes multiple variants of celeste as shown below, plus details as defined in
3690-422: The brightness of sunlight, many people wear sunglasses . Cars , many helmets and caps are equipped with visors to block the Sun from direct vision when the Sun is at a low angle. Sunshine is often blocked from entering buildings through the use of walls , window blinds , awnings , shutters , curtains , or nearby shade trees . Sunshine exposure is needed biologically for the production of Vitamin D in
3772-445: The change in solar energy in summer and winter. For example, at latitudes of 65 degrees, this can vary by more than 25% as a result of 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
3854-741: The color of the stone. In the 1870s, the French sculptor Frédéric Bartholdi began the construction of what would later become the Statue of Liberty . Over time, exposure to the elements caused the copper structure to develop its distinctive patina , now recognized as iconic cyan. Following this, there was a significant advancement in the use of cyan during the late 19th and early 20th centuries. Impressionist artists, such as Claude Monet in his renowned Water Lilies , effectively incorporated cyan hues into their works. Deviating from traditional interpretations of local color under neutral lighting conditions,
3936-559: The colors on a computer or television display, cyan is made by mixing equal amounts of green and blue light . Cyan is the complement of red ; it can be made by the removal of red from white. Mixing red light and cyan light at the right intensity will make white light. Different shades of cyan can vary in terms of hue, chroma (also known as saturation, intensity, or colorfulness), or lightness (or value, tone, or brightness), or any combination of these characteristics. Differences in value can also be referred to as tints and shades, with
4018-443: The direct radiation is not blocked by clouds, it is experienced as sunshine . The warming of the ground (and other objects) depends on the absorption of the electromagnetic radiation in the form of heat . The amount of radiation intercepted by a planetary body varies inversely with the square of the distance between the star and the planet. Earth's orbit and obliquity change with time (over thousands of years), sometimes forming
4100-522: The distance to the Sun and thus on the time of year. It is about 3.3% higher than average in January and 3.3% lower in July (see below). If the extraterrestrial solar radiation is 1,367 watts per square meter (the value when the Earth–Sun distance is 1 astronomical unit ), then the direct sunlight at Earth's surface when the Sun is at the zenith is about 1,050 W/m , but the total amount (direct and indirect from
4182-403: The entire region between the horizon and sun both in the morning and afternoon ; generally, the higher the sun is during the day and the year, the less visible celeste and variations will be. In particular, in the morning across the sun and the horizon in the early hours with the rising of the star , sometimes even until noon, until they are reduced to a few stripes on the horizon, where
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#17327933840734264-413: The focus of artists was on accurately depicting perceived color and the influence of light on altering object hues. Specifically, daylight plays a significant role in shifting the perceived color of objects toward cyan hues. In 1917, the color term teal was introduced to describe deeper shades of cyan. In the late 19th century, while traditional nomenclature of red , yellow , and blue persisted,
4346-402: The gradation of near-perfectly sunny and clear sky, the color of an ideal sky, it is difficult to see pure celeste, especially during the coldest or most unstable seasons; instead, generically the sky shows the color of the other conventional celeste with 100% of blue, recalling a light zenithal blue and the next other types of sky blue ; this is not surprising due to the best diffusion of
4428-435: The ground, both the eccentricity of Earth's elliptic orbit and the attenuation by Earth's atmosphere have to be taken into account. The extraterrestrial solar illuminance ( E ext ), corrected for the elliptic orbit by using the day number of the year (dn), is given to a good approximation by where dn=1 on January 1; dn=32 on February 1; dn=59 on March 1 (except on leap years, where dn=60), etc. In this formula dn–3
4510-514: The hues evolved, the printing industry maintained the use of the traditional terms red , yellow , and blue . Consequently, pinpointing the exact date of origin for CMYK , in which cyan serves as a primary color, proves challenging . In August 1991, the HP Deskwriter 500C became the first Deskwriter to offer color printing as an option. It used interchangeable black and color (cyan, magenta, and yellow) inkjet print cartridges. With
4592-501: The inclusion of cyan ink in printers, the term "cyan" has become widely recognized in both home and office settings. According to TUP/Technology User Profile 2020, approximately 70% of online American adults regularly use a home printer. Its name is derived from the Ancient Greek word kyanos (κύανος), meaning "dark blue enamel, Lapis lazuli ". It was formerly known as "cyan blue" or cyan-blue, and its first recorded use as
4674-474: The infobox above. Displayed at right is the web colour light sky blue . It is close in shade to baby blue . Displayed at right is the colour medium sky blue . This is the colour that is called sky blue in Crayola crayons. This colour was formulated by Crayola in 1958. "Sky blue" appears in the 32, 48, 64, 96 and 120 packs of crayons. Displayed at right is the colour vivid sky blue . Deep sky blue
4756-435: The integration over the orbital period (also invariant) is a constant. If we assume the solar radiation power P as a constant over time and the solar irradiation given by the inverse-square law , we obtain also the average insolation as a constant. However, the seasonal and latitudinal distribution and intensity of solar radiation received at Earth's surface does vary. The effect of Sun angle on climate results in
4838-458: The light within a specific sensitivity range. Many animals (including humans) have a sensitivity range of approximately 400–700 nm, and given optimal conditions the absorption and scattering by Earth's atmosphere produces illumination that approximates an equal-energy illuminant for most of this range. The useful range for color vision in humans, for example, is approximately 450–650 nm. Aside from effects that arise at sunset and sunrise,
4920-405: The maximum light , but is more difficult because of the major weather instability. In anyway, since sunlight is strongest at the horizon , that is where the pure celeste is more evident, producing the tonalities of the cyan , very close to the white . Alternatively, other variants, like Celeste polvere, Pallido and Velato , are visible towards the horizon when the sun is near to
5002-464: The only listed carcinogens that are known to have health benefits, and a number of public health organizations state that there needs to be a balance between the risks of having too much sunlight or too little. There is a general consensus that sunburn should always be avoided. Epidemiological data shows that people who have more exposure to sunlight have less high blood pressure and cardiovascular-related mortality. While sunlight (and its UV rays) are
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#17327933840735084-410: The past 400 years or cosmogenic radionuclides for going back 10,000 years. Such reconstructions have been done. These studies show that in addition to the solar irradiance variation with the solar cycle (the (Schwabe) cycle), the solar activity varies with longer cycles, such as the proposed 88 year (Gleisberg cycle), 208 year (DeVries cycle) and 1,000 year (Eddy cycle). The solar constant
5166-401: The principal source of illumination is sunlight as mediated by the atmosphere. While the color of the sky is usually determined by Rayleigh scattering , an exception occurs at sunset and twilight. "Preferential absorption of sunlight by ozone over long horizon paths gives the zenith sky its blueness when the sun is near the horizon". The Sun may be said to illuminate , which is a measure of
5248-496: The printing industry initiated a shift towards utilizing magenta and cyan inks for red and blue hues, respectively. This transition aimed to establish a more versatile color gamut achievable with only three primary colors. In 1949, a document in the printing industry stated: “The four-color set comprises Yellow , Red (magenta) , Blue (cyan) , Black ”. This practice of labeling magenta , yellow , and cyan as red , yellow , and blue persisted until 1961. As
5330-517: The prominent dome of the Goharshad Mosque in Iran , built in 1418, showcases this trend. Additionally, Jacopo da Pontormo's use of a teal shade for Mary's robe in the 1528 painting Carmignano Visitation demonstrates the allure for these hues. During the 16th century, speakers of the English language began using the term turquoise to describe the cyan color of objects that resembled
5412-443: The radiance at the center of the sun's disk is somewhat higher than the average over the whole disk due to limb darkening .) Multiplying this by π gives an upper limit to the irradiance which can be focused on a surface using mirrors: 48.5 MW/m . The spectrum of the Sun's solar radiation can be compared to that of a black body with a temperature of about 5,800 K (see graph). The Sun emits EM radiation across most of
5494-443: The redistribution of solar energy are considered a likely cause for the coming and going of recent ice ages (see: Milankovitch cycles ). Space-based observations of solar irradiance started in 1978. These measurements show that the solar constant is not constant. It varies on many time scales, including the 11-year sunspot solar cycle. When going further back in time, one has to rely on irradiance reconstructions, using sunspots for
5576-581: The relevant satellite observations indicate a value closer to 1,361 W/m is more realistic. Since 1978, a series of overlapping NASA and ESA satellite experiments have measured total solar irradiance (TSI) – the amount of solar radiation received at the top of Earth's atmosphere – as 1.365 kilowatts per square meter (kW/m ). TSI observations continue with the ACRIMSAT /ACRIM3, SOHO /VIRGO and SORCE /TIM satellite experiments. Observations have revealed variation of TSI on many timescales, including
5658-500: The remnants of ancient plant and animal matter, formed using energy from sunlight and then trapped within Earth for millions of years. The effect of sunlight is relevant to painting , evidenced for instance in works of Édouard Manet and Claude Monet on outdoor scenes and landscapes. Many people find direct sunlight to be too bright for comfort; indeed, looking directly at the Sun can cause long-term vision damage. To compensate for
5740-486: The skin, a vital compound needed to make strong bone and muscle in the body. In many world religions, such as Hinduism , the Sun is considered to be a god , as it is the source of life and energy on Earth. The Sun was also considered to be a god in Ancient Egypt . Sunbathing is a popular leisure activity in which a person sits or lies in direct sunshine. People often sunbathe in comfortable places where there
5822-411: The sky, as Light Sky Blue and similar gradations, among which the other conventional celeste, similar to the light blue sky colours rather than the pure celeste . One scientific explanation needs to be made: the sun emits light across the entire electromagnetic spectrum and so celeste, which is very close to the white with a RGB of 178,255,255, is very luminous, and so visible in the direction of
5904-448: The solar atmosphere, but this does not explain these findings. The only direct signature of the nuclear processes in the core of the Sun is via the very weakly interacting neutrinos . Although the solar corona is a source of extreme ultraviolet and X-ray radiation, these rays make up only a very small amount of the power output of the Sun (see spectrum at right). The spectrum of nearly all solar electromagnetic radiation striking
5986-491: The solar light it receives. The actual illumination of the surface is about 14,000 lux, comparable to that on Earth "in the daytime with overcast clouds". Sunlight on Mars would be more or less like daylight on Earth during a slightly overcast day, and, as can be seen in the pictures taken by the rovers, there is enough diffuse sky radiation that shadows would not seem particularly dark. Thus, it would give perceptions and "feel" very much like Earth daylight. The spectrum on
6068-592: The solar magnetic cycle and many shorter periodic cycles. TSI provides the energy that drives Earth's climate, so continuation of the TSI time-series database is critical to understanding the role of solar variability in climate change. Since 2003, the SORCE Spectral Irradiance Monitor (SIM) has monitored Spectral solar irradiance (SSI) – the spectral distribution of the TSI. Data indicate that SSI at UV (ultraviolet) wavelength corresponds in
6150-408: The spectral composition changes primarily in respect to how directly sunlight is able to illuminate. When illumination is indirect, Rayleigh scattering in the upper atmosphere will lead blue wavelengths to dominate. Water vapour in the lower atmosphere produces further scattering and ozone, dust and water particles will also absorb particular wavelengths. The existence of nearly all life on Earth
6232-434: The stone with the same name, is a shade in the green spectrum of cyan hues. Celeste is a lightly tinted cyan that represents the color of a clear sky. Other colors in the cyan color range are electric blue , aquamarine , and others described as blue-green . Cyan boasts a rich and diverse history, holding cultural significance for millennia. In ancient civilizations, turquoise , valued for its aesthetic appeal, served as
6314-441: The sun because it is there the maximum quantity of solar light, especially towards the horizon, even if human eyes can only perceive the visible light . Here because celeste and variations are easier to be visible in the warm seasons because of the inclination of a hemisphere with respect to the sun , spring and especially summer , with the optimization of solar light, hours of daylight and meteorological factors . Being
6396-605: The sunlight than was possible through glycolysis alone, and human population began to grow. During the Neolithic Revolution , the domestication of plants and animals further increased human access to solar energy. Fields devoted to crops were enriched by inedible plant matter, providing sugars and nutrients for future harvests. Animals that had previously provided humans with only meat and tools once they were killed were now used for labour throughout their lives, fueled by grasses inedible to humans. Fossil fuels are
6478-486: The surface is slightly redder than that on Earth, due to scattering by reddish dust in the Martian atmosphere. For comparison, sunlight on Saturn is slightly brighter than Earth sunlight at the average sunset or sunrise. Even on Pluto, the sunlight would still be bright enough to almost match the average living room. To see sunlight as dim as full moonlight on Earth, a distance of about 500 AU (~69 light-hours )
6560-474: The timing of melatonin synthesis, maintenance of normal circadian rhythms , and reduced risk of seasonal affective disorder . Long-term sunlight exposure is known to be associated with the development of skin cancer , skin aging , immune suppression , and eye diseases such as cataracts and macular degeneration . Short-term overexposure is the cause of sunburn , snow blindness , and solar retinopathy . UV rays, and therefore sunlight and sunlamps, are
6642-535: The web. Different bodies of the Solar System receive light of an intensity inversely proportional to the square of their distance from Sun. A table comparing the amount of solar radiation received by each planet in the Solar System at the top of its atmosphere: The actual brightness of sunlight that would be observed at the surface also depends on the presence and composition of an atmosphere . For example, Venus's thick atmosphere reflects more than 60% of
6724-456: The zenith, always with discrete or good conditions of visibility. In the afternoon, always with good conditions, these three type of celeste, together with softer and less bright shades of celeste, are visible at straight angle from north to south, until around sunset . In reality, it can be difficult to observe the pure celeste , being the color of a clear day with optimal meteorological factories; other shades of blue are often visible in
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