Sunrise (or sunup) is the moment when the upper rim of the Sun appears on the horizon in the morning,[1] at the start of the Sun path. The term can also refer to the entire process of the solar disk crossing the horizon.
Although the Sun appears to "rise" from the horizon, it is actually the Earth's motion that causes the Sun to appear. The illusion of a moving Sun results from Earth observers being in a rotating reference frame; this apparent motion caused many cultures to have mythologies and religions built around the geocentric model, which prevailed until astronomer Nicolaus Copernicus formulated his heliocentric model in the 16th century.[2]
Architect Buckminster Fuller proposed the terms "sunsight" and "sunclipse" to better represent the heliocentric model, though the terms have not entered into common language.[3][4]
Astronomically, sunrise occurs for only an instant, namely the moment at which the upper limb of the Sun appears tangent to the horizon.[1] However, the term sunrise commonly refers to periods of time both before and after this point:
The stage of sunrise known as false sunrise actually occurs before the Sun truly reaches the horizon because Earth's atmosphere refracts the Sun's image. At the horizon, the average amount of refraction is 34 arcminutes, though this amount varies based on atmospheric conditions.[1]
Also, unlike most other solar measurements, sunrise occurs when the Sun's upper limb, rather than its center, appears to cross the horizon. The apparent radius of the Sun at the horizon is 16 arcminutes.[1]
These two angles combine to define sunrise to occur when the Sun's center is 50 arcminutes below the horizon, or 90.83° from the zenith.[1]
The timing of sunrise varies throughout the year and is also affected by the viewer's latitude and longitude, altitude, and time zone. These changes are driven by the axial tilt of Earth, daily rotation of the Earth, the planet's movement in its annual elliptical orbit around the Sun, and the Earth and Moon's paired revolutions around each other. The analemma can be used to make approximate predictions of the time of sunrise.
In late winter and spring, sunrise as seen from temperate latitudes occurs earlier each day, reaching its earliest time shortly before the summer solstice; although the exact date varies by latitude. After this point, the time of sunrise gets later each day, reaching its latest shortly after the winter solstice, also varying by latitude. The offset between the dates of the solstice and the earliest or latest sunrise time is caused by the eccentricity of Earth's orbit and the tilt of its axis, and is described by the analemma, which can be used to predict the dates.
Variations in atmospheric refraction can alter the time of sunrise by changing its apparent position. Near the poles, the time-of-day variation is extreme, since the Sun crosses the horizon at a very shallow angle and thus rises more slowly.[1]
Accounting for atmospheric refraction and measuring from the leading edge slightly increases the average duration of day relative to night. The sunrise equation, however, which is used to derive the time of sunrise and sunset, uses the Sun's physical center for calculation, neglecting atmospheric refraction and the non-zero angle subtended by the solar disc.
Neglecting the effects of refraction and the Sun's non-zero size, whenever sunrise occurs, in temperate regions it is always in the northeast quadrant from the March equinox to the September equinox and in the southeast quadrant from the September equinox to the March equinox.[6] Sunrises occur approximately due east on the March and September equinoxes for all viewers on Earth.[7] Exact calculations of the azimuths of sunrise on other dates are complex, but they can be estimated with reasonable accuracy by using the analemma.
The figure on the right is calculated using the solar geometry routine in Ref.[8] as follows:
An interesting feature in the figure on the right is apparent hemispheric symmetry in regions where daily sunrise and sunset actually occur.
This symmetry becomes clear if the hemispheric relation in to the sunrise equation is applied to the x- and y-components of the solar vector presented in Ref.[8]
Air molecules and airborne particles scatter white sunlight as it passes through the Earth's atmosphere. This is done by a combination of Rayleigh scattering and Mie scattering.[9]
As a ray of white sunlight travels through the atmosphere to an observer, some of the colors are scattered out of the beam by air molecules and airborne particles, changing the final color of the beam the viewer sees. Because the shorter wavelength components, such as blue and green, scatter more strongly, these colors are preferentially removed from the beam.[9]
At sunrise and sunset, when the path through the atmosphere is longer, the blue and green components are removed almost completely, leaving the longer-wavelength orange and red hues seen at those times. The remaining reddened sunlight can then be scattered by cloud droplets and other relatively large particles to light up the horizon red and orange.[10] The removal of the shorter wavelengths of light is due to Rayleigh scattering by air molecules and particles much smaller than the wavelength of visible light (less than 50 nm in diameter).[11][12] The scattering by cloud droplets and other particles with diameters comparable to or larger than the sunlight's wavelengths (more than 600 nm) is due to Mie scattering and is not strongly wavelength-dependent. Mie scattering is responsible for the light scattered by clouds, and also for the daytime halo of white light around the Sun (forward scattering of white light).[13][14][15]
Sunset colors are typically more brilliant than sunrise colors, because the evening air contains more particles than morning air.[9][10][12][15] Ash from volcanic eruptions, trapped within the troposphere, tends to mute sunset and sunrise colors, while volcanic ejecta that is instead lofted into the stratosphere (as thin clouds of tiny sulfuric acid droplets), can yield beautiful post-sunset colors called afterglows and pre-sunrise glows. A number of eruptions, including those of Mount Pinatubo in 1991 and Krakatoa in 1883, have produced sufficiently high stratospheric sulfuric acid clouds to yield remarkable sunset afterglows (and pre-sunrise glows) around the world. The high altitude clouds serve to reflect strongly reddened sunlight still striking the stratosphere after sunset, down to the surface.
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Conservation status
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 Vulnerable (IUCN 3.1)[1] |
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CITES Appendix I [1]
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Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Family: | Bovidae |
| Subfamily: | Hippotraginae |
| Genus: | Oryx |
| Species: |
O. leucoryx
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| Oryx leucoryx
(Pallas, 1777)
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The Arabian oryx or white oryx (Oryx leucoryx) is a medium-sized antelope with a distinct shoulder bump, long, straight horns, and a tufted tail.[2] It is a bovid, and the smallest member of the genus Oryx, native to desert and steppe areas of the Arabian Peninsula. The Arabian oryx was extinct in the wild by the early 1970s, but was saved in zoos and private reserves, and was reintroduced into the wild starting in 1980.
In 1986, the Arabian oryx was classified as endangered on the IUCN Red List, and in 2011, it was the first animal to revert to vulnerable status after previously being listed as extinct in the wild. It is listed in CITES Appendix I. In 2016, populations were estimated at 1,220 individuals in the wild, including 850 mature individuals, and 6,000–7,000 in captivity worldwide.[1]
The taxonomic name Oryx leucoryx is from the Greek orux (gazelle or antelope) and leukos (white). The Arabian oryx is also called the white oryx in English, dishon in Hebrew,[3] and is known as maha, wudhaihi, baqar al-wahsh, and boosolah in Arabic.[4]
The name "oryx" was introduced by Peter Simon Pallas in 1767 for the common eland as Antilope oryx. He also scientifically described the Arabian oryx as Oryx leucoryx, giving its range as "Arabia, and perhaps Libya". In 1816, Henri Marie Ducrotay de Blainville subdivided the antelope group, adopted Oryx as a genus name, and changed the species name Antilope oryx to Oryx gazella. In 1826, Martin Lichtenstein confused matters by transferring the name Oryx leucoryx to the scimitar oryx, now Oryx dammah. The Zoological Society of London obtained the first living individual in Europe in 1857. Not realizing this might be the Oryx leucoryx of previous authors, John Edward Gray proposed calling it Oryx beatrix after Princess Beatrice of the United Kingdom. Oldfield Thomas renamed the scimitar oryx as Oryx algazal in 1903 and gave the Arabian oryx its original name.[4]
The Arabian oryx' coat is an almost luminous white, the undersides and legs are brown, and black stripes occur where the head meets the neck, on the forehead, on the nose, and going from the horn down across the eye to the mouth. Both sexes have long, straight or slightly curved, ringed horns which are 0.61–1.49 m (2–4.9 ft). It stands between 0.79 and 1.25 m (2.6 and 4.1 ft) tall at the shoulder and typically weighs between 220 to 460 lb (100 to 209 kg).[5][2]
Historically, the Arabian oryx probably ranged throughout most of the Middle East. In the early 1800s, they could still be found in the Sinai, Palestine, the Transjordan, much of Iraq, and most of the Arabian Peninsula. During the 19th and early 20th centuries, their range was pushed back towards Saudi Arabia, and by 1914, only a few survived outside that country. A few were reported in Jordan into the 1930s, but by the mid-1930s, the only remaining populations were in the Nafud Desert in northwestern Saudi Arabia and the Rub' al Khali in the south.[2]
In the 1930s, Arabian princes and oil company clerks started hunting Arabian oryxes with automobiles and rifles. Hunts grew in size, and some were reported to employ as many as 300 vehicles. By the middle of the 20th century, the northern population was effectively extinct.[2] The last Arabian oryx in the wild before reintroduction was reported in 1972.[6]
Arabian oryxes prefer to range in gravel deserts or hard sand, where their speed and endurance will protect them from most predators and hunters on foot. In the sand deserts in Saudi Arabia, they used to be found in the hard sand areas of the flats between the softer dunes and ridges.[2]
Arabian oryxes have been reintroduced to Oman, Saudi Arabia, Israel, the United Arab Emirates, Syria, and Jordan. A small population was introduced on Hawar Island, Bahrain, and large semi-managed populations at several sites in Qatar and the UAE. The total reintroduced population is now estimated to be around 1,000. This puts the Arabian oryx well over the threshold of 250 mature individuals needed to qualify for endangered status. However, the majority of the population is concentrated in Saudi Arabia.[1]
The Arabian oryx rests during the heat of the day. A herd in Oman can range over 3,000 km2 (1,200 sq mi). Packs are of mixed sex and usually comprise between 2 and 15 induvials, though herds of up to 100 have been reported. Arabian oryxes are generally not aggressive toward one another, which allows herds to exist peacefully for some time.[7]
The diets of the Arabian oryx consist mainly of grasses, but it eats a large variety of vegetation, including buds, herbs, fruit, tubers and roots. Herds follow infrequent rains to eat the new plants that grow afterwards. They can go for several weeks without water.[7] In Oman, it primarily eats grasses of the genus Stipagrostis, flowers from Stipagrostis plants appeared highest in crude protein and water, while leaves seemed a better food source with other vegetation.[8]
When the Arabian oryx is not wandering its habitat or eating, it digs shallow depressions in the soft ground under shrubs or trees for resting. They can detect rainfall from a distance and follow in the direction of fresh plant growth. The number of individuals in a herd can vary greatly (up to 100 have been reported occasionally), but the average is 10 or fewer individuals.[9] Bachelor herds do not occur, and single territorial males are rare. Herds establish a straightforward hierarchy that involves all females and males above the age of about seven months.[10] Arabian oryxes tend to maintain visual contact with other herd members, with subordinate males taking positions between the main body of the herd and the outlying females. If separated, males will search areas where the herd last visited, settling into a solitary existence until the herd's return. Where water and grazing conditions permit, male Arabian oryxes establish territories. Bachelor males are solitary.[11] A dominance hierarchy is created within the herd by posturing displays, which avoid the danger of serious injury their long, sharp horns could potentially inflict. Males and females use their horns to defend the sparse territorial resources against interlopers.[12]
The Arabian oryx changes its physiology and behaviour at different times of the year to increase survival during times when food and water are in limited supply. During the summer, when droughts are common in the desert environments where it lives, the Arabian oryx will drastically reduce its minimal fasting metabolic rate by lying completely inactive beneath shade trees during the day and ranging over smaller areas at night to forage.[13] By letting its body temperature rise during the heat of the day, it uses less evaporative cooling and retains more body water, and at night, the cool night air lowers its temperature back to the normal range.[14] The oryx's arterial blood temperature is partly powered by a network of small arterial vessels with a large surface area called the rete mirabile, which branches from the two carotid arteries to the brain and allows for heat exchange between warm arterial blood and the cooler blood in the sinus cavities.[14] Because of these changes in behaviour and physiology, it was shown that Arabian oryx can reduce their urine volume, faecal water loss, and resting metabolic rate by at least 50%.[15]
The Arabian wolf is the Arabian oryx's only predator. In captivity and safe conditions in the wild, it has a maximum life span of up to 20 years.[11] In periods of drought, though, their life expectancy may be significantly reduced by malnutrition and dehydration. Other causes of death include fights between males, snakebites, disease, and drowning during floods.[16]
The Arabian oryx is the national animal of Jordan, Oman, the United Arab Emirates,[17] Bahrain, and Qatar.[18]
The Arabian oryx is also the namesake of several businesses on the Arabian peninsula, notably Al Maha Airways and Al Maha Petroleum.
In the King James Version of the Bible, the word re'em is translated as 'unicorn'. In Modern Hebrew, the name re'em lavan, meaning white oryx, is used in error for the scimitar-horned oryxes living in the sanctuary Yotvata Hai Bar near Eilat.[19] The scimitar oryx is called re'em Sahara. The Arabian name ri'ïm is the equivalent of the Hebrew name re'em, also meaning white oryx, suggesting a borrowing from the Early Modern Era.
A Qatari oryx named "Orry" was chosen as the official games mascot for the 2006 Asian Games in Doha,[20] and is shown on tailfins of planes belonging to Middle Eastern airline Qatar Airways.
The myth of the one-horned unicorn may be based on oryxes that have lost one horn. Aristotle and Pliny the Elder held that the oryx was the unicorn's "prototype".[21] From certain angles, the oryx may seem to have one horn rather than two,[22][23] and given that its horns are made from hollow bone that cannot be regrown, if an Arabian oryx were to lose one of its horns, for the rest of its life, it would have only one.[21]
Another source for the concept may have originated from the translation of the Hebrew word re'em into Greek as μονόκερως, monokeros, in the Septuagint.[24] In Psalm 22:21, the word karen, meaning horn, is written in singular. The Roman Catholic Vulgata and the Douay-Rheims Bible translated re'em as rhinoceros; other translations are names for a wild bull, wild oxen, buffalo, or gaur, but in some languages, a word for unicorn is maintained. The Arabic translation alrim is the correct choice etymologically, meaning 'white oryx'.[25]
The Phoenix Zoo and the Fauna and Flora Preservation Society of London (now Fauna and Flora International), with financial help from the World Wildlife Fund, are credited with saving the Arabian oryx from extinction. In 1962, these groups started the first captive-breeding herd in any zoo, at the Phoenix Zoo, sometimes referred to as "Operation Oryx".[26][27] Starting with nine animals, the Phoenix Zoo has had over 240 successful births. From Phoenix, Arabian oryxes were sent to other zoos and parks to start new herds.
In 1968, Sheikh Zayed bin Sultan Al Nahyan of Abu Dhabi, out of concern for the land's wildlife, particularly ungulates such as the Arabian oryx, founded the Al Ain Zoo to conserve them.[28]
Arabian oryxes were hunted to extinction in the wild by 1972. By 1980, the number of Arabian oryxes in captivity had increased to the point that Arabian oryx reintroduction was started. The first release, to Oman, was attempted with Arabian oryxes from the San Diego Wild Animal Park.[6] Although numbers in Oman have declined, there are now wild populations in Saudi Arabia and Israel,[29][30] as well. One of the largest populations is found in Mahazat as-Sayd Protected Area, a large, fenced reserve in Saudi Arabia, covering more than 2,000 km2 (770 sq mi).[1]
On June 28, 2007, Oman's Arabian Oryx Sanctuary was the first site ever to be removed from the UNESCO World Heritage List. UNESCO's reason for this was the Omani government's decision to open 90% of the site to oil prospecting. The Arabian oryx population on the site has been reduced from 450 in 1996 to only 65 in 2007. At that time, there were fewer than four breeding pairs left on the site.[31][needs update]
In June 2011, the Arabian oryx was relisted as vulnerable by the IUCN Red List. The IUCN estimated there were more than 1,200 Arabian oryx in the wild as of 4 December 2020[update] 2016, with 6,000–7,000 held in captivity worldwide in zoos, preserves, and private collections. Some of these are in large, fenced enclosures (free-roaming), including those in Syria (Al Talila), Bahrain, Qatar, and the UAE.[1] This is the first time the IUCN has reclassified a species as vulnerable after it had been listed as extinct in the wild.[32] The Arabian oryx is also listed in CITES Appendix I.[1]
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Wear comfortable clothes, closed shoes, and light layers as mornings in the desert can be cool.
Hot Air Balloon Dubai offers unmatched sunrise views, desert scenery, and a peaceful adventure unlike any other activity in Dubai.
Yes, private Hot Air Balloon Dubai flights are available for couples, families, and small groups.
