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80-461: Ashalim Plot A (Negev Energy) is a 121 megawatt parabolic trough plant with 4.5 hours of thermal energy storage . The Ashalim Plot B (Megalim) hosts a solar power tower . It has an installed capacity of 121 megawatts, concentrating 50,600 computer-controlled heliostats enough to power 120,000 homes. Electricity production commenced in September 2019, producing 320 GWhr of energy per year. The project

160-493: A change in daily floral and animal events can be observed, the season is changing. In this sense, ecological seasons are defined in absolute terms, unlike calendar-based methods in which the seasons are relative. If specific conditions associated with a particular ecological season do not normally occur in a particular region, then that area cannot be said to experience that season on a regular basis. Six ecological seasons can be distinguished without fixed calendar-based dates like

240-486: A factor of 9 compared to the PV stations tendered in 2019 at the same spot (see above). Similarly, the project on Plot A at NIS 0.76 per kWh, but including 4.5 hours of molten salt storage, delivers four times more expensive power than the results of tenders for solar plus 4 hours of storage awarded at the beginning of 2021 at NIS0.17/kWh ($ 0.054) to be delivered by 2023. Parabolic trough A parabolic trough collector (PTC)

320-404: A four-season model to demarcate the warmest and coldest seasons, which are further separated by two intermediate seasons. Calendar-based reckoning defines the seasons in relative rather than absolute terms, so the coldest quarter-year is considered winter even if floral activity is regularly observed during it, despite the traditional association of flowers with spring and summer. The major exception

400-528: A full-scale steam engine powered by low-pressure water, enabling him to patent the entire solar engine system by 1912. Shuman built the world's first solar thermal power station in Maadi , Egypt between 1912 and 1913. Shuman's plant used parabolic troughs to power a 45–52 kilowatt (60–70  hp ) engine that pumped more than 22,000 litres of water per minute from the Nile River to adjacent cotton fields. Although

480-457: A method for storing the energy, such as a thermocline tank, which uses a mixture of silica sand and quartzite rock to displace a significant portion of the volume in the tank. It is then filled with the heat transfer fluid, typically a molten nitrate salt . As of 2014, the largest solar thermal power systems using parabolic trough technology include the 354 MW SEGS plants in California,

560-506: A partnership with Aera Energy that would bring parabolic troughs to the South Belridge Oil Field , near Bakersfield , California. In 1897, Frank Shuman , a U.S. inventor, engineer and solar energy pioneer built a small demonstration solar engine that worked by reflecting solar energy onto square boxes filled with ether, which has a lower boiling point than water, and were fitted internally with black pipes which in turn powered

640-582: A result from exposure to humidity. GlassPoint Solar , the company that created the Enclosed Trough design, states its technology can produce heat for EOR for about $ 5 per million British thermal units in sunny regions, compared to between $ 10 and $ 12 for other conventional solar thermal technologies. Enclosed troughs are currently being used at the Miraah solar facility in Oman . In November 2017, GlassPoint announced

720-482: A steam engine. In 1908 Shuman formed the Sun Power Company with the intent of building larger solar power plants. He, along with his technical advisor A. S. E. Ackermann and British physicist Sir Charles Vernon Boys , developed an improved system using mirrors to reflect solar energy upon collector boxes, increasing heating capacity to the extent that water could now be used instead of ether. Shuman then constructed

800-542: A tender for another NIS 150 ($ 43) million PV plant at a record low price of 8.68 agorot (3 cents) per kilowatt hour. According to a press release of the National Infrastructure Minister of Israel , the establishment has several motivations: The concentrated solar power project in Ashalim was announced in 2008 and awarded in a competitive auction 2012 at NIS0.79 ($ 0.22) per kilowatt hour for Plot B – almost

880-774: Is 1 November ( Samhain , the Celtic origin of Halloween ); spring starts 1 February (Celtic Imbolc ); summer begins 1 May ( Beltane , the Celtic origin of May Day ); the first day of autumn is 1 August (Celtic Lughnasadh ). The traditional calendar in China has 4 seasons based on 24 periods, twelve of which are called zhōngqi and twelve of which are known as jiéqi . These periods are collectively known in English as "solar terms" or "solar breaths". The four seasons chūn ( 春 ), xià ( 夏 ), qiū ( 秋 ), and dōng ( 冬 )—translated as "spring", "summer", "autumn", and "winter" —each center on

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960-639: Is a 7% variation in sunlight received. Orbital eccentricity can influence temperatures, but on Earth, this effect is small and is more than counteracted by other factors; research shows that the Earth as a whole is actually slightly warmer when farther from the sun. This is because the Northern Hemisphere has more land than the Southern, and land warms more readily than sea. Any noticeable intensification of southern winters and summers due to Earth's elliptical orbit

1040-410: Is a type of solar thermal collector that is straight in one dimension and curved as a parabola in the other two, lined with a polished metal mirror . The sunlight which enters the mirror parallel to its plane of symmetry is focused along the focal line , where objects are positioned that are intended to be heated. In a solar cooker , for example, food is placed at the focal line of a trough, which

1120-415: Is about 15%, similar to PV (Photovoltaic Cells) but less than Stirling dish concentrators . A parabolic trough is made of a number of solar collector modules ( SCM ) fixed together to move as one solar collector assembly ( SCA ). A SCM could have a length up to 15 metres (49 ft 3 in) or more. About a dozen or more of SCM make each SCA up to 200 metres (656 ft 2 in) length. Each SCA

1200-501: Is also known as "obliquity of the ecliptic ".) Regardless of the time of year, the northern and southern hemispheres always experience opposite seasons. This is because during summer or winter , one part of the planet is more directly exposed to the rays of the Sun than the other, and this exposure alternates as the Earth revolves in its orbit. For approximately half of the year (from around March   20 to around September   22),

1280-530: Is an independently-tracking parabolic trough. A SCM may be made as a single-piece parabolic mirror or assembled with a number of smaller mirrors in parallel rows. Smaller modular mirrors require smaller machines to build the mirror, reducing cost. Cost is also reduced in case of the need of replacing a damaged mirror. Such damage may occur due to being hit by an object during bad weather. In addition, V-type troughs exist which are made from 2 mirrors and placed at an angle towards each other. In 2009, scientists at

1360-572: Is contradictory. These are mainly a matter of custom and not generally proclaimed by governments north or south of the equator for civil purposes. Meteorological seasons are reckoned by temperature, with summer being the hottest quarter of the year and winter the coldest quarter of the year. In 1780 the Societas Meteorologica Palatina (which became defunct in 1795), an early international organization for meteorology, defined seasons as groupings of three whole months as identified by

1440-476: Is cooked when the trough is aimed so the Sun is in its plane of symmetry. For other purposes, a tube containing a fluid runs the length of the trough at its focal line. The sunlight is concentrated on the tube and the fluid heated to a high temperature by the energy of the sunlight. The hot fluid can be piped to a heat engine (e.g. ORC or water/steam Rankine cycle), which uses the heat energy to drive machinery, or to generate electricity. This solar energy collector

1520-418: Is defined as when the mean daily temperature permanently rises above 0 °C. The beginning of summer is defined as when the temperature permanently rises above +10 °C, autumn as when the temperature permanently falls below +10 °C, and winter as when the temperature permanently falls below 0 °C. In Finland, "permanently" is defined as when the mean daily averaged temperature remains above or below

1600-457: Is in the tropics where, as already noted, the winter season is not observed. The four seasons have been in use since at least Roman times, as in Rerum rusticarum of Varro Varro says that spring, summer, autumn, and winter start on the 23rd day of the sun's passage through Aquarius, Taurus, Leo, and Scorpio, respectively. Nine years before he wrote, Julius Caesar had reformed the calendar, so Varro

1680-452: Is inconsistent by nature, methods for energy storage have been studied, for instance, the single-tank ( thermocline ) storage technology for large-scale solar thermal power plants. The thermocline tank approach uses a mixture of silica sand and quartzite rock to displace a significant portion of the volume in the tank. Then it is filled with the heat transfer fluid, typically a molten nitrate salt . The enclosed trough architecture encapsulates

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1760-625: Is mitigated by the abundance of water in the Southern Hemisphere. Seasonal weather fluctuations (changes) also depend on factors such as proximity to oceans or other large bodies of water, currents in those oceans, El Niño /ENSO and other oceanic cycles, and prevailing winds . In the temperate and polar regions , seasons are marked by changes in the amount of sunlight , which in turn often causes cycles of dormancy in plants and hibernation in animals. These effects vary with latitude and with proximity to bodies of water. For example,

1840-449: Is one of the primary reasons for the Earth's seasons, as illustrated by the diagram to the right. Minor variation in the direction of the axis, known as axial precession , takes place over the course of 26,000 years, and therefore is not noticeable to modern human civilization. The seasons result from the Earth's axis of rotation being tilted with respect to its orbital plane by an angle of approximately 23.4 degrees . (This tilt

1920-436: Is the most common and best known type of parabolic trough. When heat transfer fluid is used to heat steam to drive a standard turbine generator, thermal efficiency ranges from 50 to 80%. The overall efficiency from collector to grid, i.e. (electrical output power)/(total impinging solar power) is about 15%, similar to photovoltaic cells but less than Stirling dish concentrators . Large-scale solar thermal power plants need

2000-421: The rainy / wet / monsoon season and the dry season . Some have a third cool , mild , or harmattan season . "Seasons" can also be dictated by the timing of important ecological events such as hurricane season , tornado season , and wildfire season . Some examples of historical importance are the ancient Egyptian seasons— flood , growth , and low water —which were previously defined by

2080-503: The Andasol 1 solar power station . Season A season is a division of the year based on changes in weather , ecology , and the number of daylight hours in a given region. On Earth , seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun . In temperate and polar regions, the seasons are marked by changes in the intensity of sunlight that reaches

2160-605: The Midwestern United States and parts of eastern Europe . The actual dates for each season vary by climate region and can shift from one year to the next. Average dates listed here are for mild and cool temperate climate zones in the Northern Hemisphere: Indigenous people in polar, temperate and tropical climates of northern Eurasia, the Americas, Africa, Oceania, and Australia have traditionally defined

2240-620: The National Renewable Energy Laboratory (NREL) and SkyFuel teamed to develop large curved sheets of metal that have the potential to be 30% less expensive than today's best collectors of concentrated solar power by replacing glass-based models with a silver polymer sheet that has the same performance as the heavy glass mirrors, but at a much lower cost and weight. It also is much easier to move and install. The glossy film uses several layers of polymers, with an inner layer of pure silver. As this renewable source of energy

2320-623: The Paracel Islands and parts of the Tibetan plateau ) may be said to have summer all year round or winter all year round. Astronomical timing as the basis for designating the temperate seasons dates back at least to the Julian Calendar used by the ancient Romans. As mentioned above, Varro wrote that spring, summer, autumn, and winter start on the 23rd day of the sun's passage through Aquarius, Taurus, Leo, and Scorpio, respectively, and that (in

2400-630: The South Pole is in the middle of the continent of Antarctica and therefore a considerable distance from the moderating influence of the southern oceans. The North Pole is in the Arctic Ocean , and thus its temperature extremes are buffered by the water. The result is that the South Pole is consistently colder during the southern winter than the North Pole during the northern winter. The seasonal cycle in

2480-560: The elliptical nature of the orbit of the Earth, as discovered by Johannes Kepler . From the March equinox it currently takes 92.75 days until the June solstice, then 93.65 days until the September equinox, 89.85 days until the December solstice and finally 88.99 days until the March equinox. Thus the time from the March equinox to the September equinox is 7.56 days longer than from the September equinox to

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2560-712: The former annual flooding of the Nile in Egypt . Seasons often hold special significance for agrarian societies, whose lives revolve around planting and harvest times, and the change of seasons is often attended by ritual . The definition of seasons is also cultural. In India, from ancient times to the present day, six seasons or Ritu based on south Asian religious or cultural calendars are recognised and identified for purposes such as agriculture and trade. The Earth's orbit exhibits approximate axial parallelism , maintaining its direction toward Polaris (the "North Star") year-round. This

2640-572: The middle of the respective seasons. Because of seasonal lag due to thermal absorption and release by the oceans, regions with a continental climate , which predominate in the Northern Hemisphere , often consider these four dates to be the start of the seasons as in the diagram, with the cross-quarter days considered seasonal midpoints. The length of these seasons is not uniform because of Earth's elliptical orbit and its different speeds along that orbit . Most calendar-based partitions use

2720-503: The ( proleptic ) Gregorian calendar agrees with the Julian calendar in the third century of the Christian era , rather than in the fourth. Currently, the most common equinox and solstice dates are March 20, June 21, September 22 or 23, and December 21; the four-year average slowly shifts to earlier times as a century progresses. This shift is a full day in about 128 years (compensated mainly by

2800-467: The 280 MW Solana Generating Station with molten salt heat storage , the 250 MW Genesis Solar Energy Project , the Spanish 200 MW Solaben Solar Power Station, and the Andasol 1 solar power station . The trough is usually aligned on a north–south axis, and rotated to track the sun as it moves across the sky each day. Alternatively, the trough can be aligned on an east–west axis; this reduces

2880-451: The Earth are just on the terminator , and hence day and night are equally divided between the two hemispheres. Around the March equinox , the Northern Hemisphere will be experiencing spring as the hours of daylight increase, and the Southern Hemisphere is experiencing autumn as daylight hours shorten. The effect of axial tilt is observable as the change in day length and the altitude of

2960-499: The Earth's surface, variations of which may cause animals to undergo hibernation or to migrate , and plants to be dormant. Various cultures define the number and nature of seasons based on regional variations, and as such there are a number of both modern and historical definitions of the seasons. The Northern Hemisphere experiences most direct sunlight during May, June, and July (thus the traditional celebration of Midsummer in June), as

3040-456: The Elder , in his Natural History , mentions the two equinoxes and the two solstices and gives the lengths of the intervals (values which were fairly correct in his day but are no longer very correct because the perihelion has moved from December into January). He then defines the seasons of autumn, winter, spring, and summer as starting half-way through these intervals. He gives "the eighth day to

3120-489: The Gregorian calendar. According to this definition, for temperate areas in the northern hemisphere, spring begins on 1 March, summer on 1 June, autumn on 1 September, and winter on 1 December. For the southern hemisphere temperate zone, spring begins on 1 September, summer on 1 December, autumn on 1 March, and winter on 1 June. In Australasia the meteorological terms for seasons apply to

3200-523: The ICZ migrates to a position south of the Equator. In meteorological terms, the solstices (the maximum and minimum insolation ) do not fall in the middles of summer and winter. The heights of these seasons occur up to 7 weeks later because of seasonal lag . Seasons, though, are not always defined in meteorological terms. In astronomical reckoning by hours of daylight alone, the solstices and equinoxes are in

3280-463: The Julian Calendar) these days were February 7, May 9, August 11, and November 10. He points out that the lengths are not equal, being 91 (in non-leap years), 94, 91, and 89 days for spring, summer, autumn, and winter, respectively. The midpoints of these seasons were March 24 or 25, June 25, September 25 or 26, and December 24 or 25, which are near to the equinoxes and solstices of his day. Pliny

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3360-466: The Kalends of January" (December 25) as the date of the winter solstice, though actually it occurred on the 22nd or 23rd at that time. Nowadays the astronomical timing has winter starting at the winter solstice, spring at the spring equinox, and so on. This is used worldwide, although some countries like Australia, New Zealand, Pakistan and Russia prefer to use meteorological reckoning. The precise timing of

3440-403: The March equinox. The times of the equinoxes and solstices are not fixed with respect to the modern Gregorian calendar, but fall about six hours later every year, amounting to one full day in four years. They are reset by the occurrence of a leap year. The Gregorian calendar is designed to keep the March equinox no later than 21 March as accurately as is practical. The calendar equinox (used in

3520-561: The Northern Hemisphere tips toward the Sun, with the maximum amount occurring on about June   21. For the other half of the year, the same happens, but in the Southern Hemisphere instead of the Northern, with the maximum around December   21. The two instants when the Sun is directly overhead at the Equator are the equinoxes . Also at that moment, both the North Pole and the South Pole of

3600-529: The Sami people in Scandinavia. Many indigenous people who no longer live directly off the land in traditional often nomadic styles, now observe modern methods of seasonal reckoning according to what is customary in their particular country or region. The North American Cree and possibly other Algonquian speaking peoples used or still use a 6-season system. The extra two seasons denoting the freezing and breaking up of

3680-486: The Southern Hemisphere. In temperate and sub-polar regions, four seasons based on the Gregorian calendar are generally recognized: spring , summer , autumn ( fall ), and winter . Ecologists often use a six-season model for temperate climate regions which are not tied to any fixed calendar dates: prevernal , vernal , estival , serotinal , autumnal , and hibernal . Many tropical regions have two seasons:

3760-571: The Sun at solar noon (the Sun's culmination ) during the year . The low angle of the Sun during the winter months means that incoming rays of solar radiation are spread over a larger area of the Earth's surface, so the light received is more indirect and of lower intensity. Between this effect and the shorter daylight hours, the axial tilt of the Earth accounts for most of the seasonal variation in climate in both hemispheres. Compared to axial parallelism and axial tilt, other factors contribute little to seasonal temperature changes. The seasons are not

3840-418: The actual solar collectors, the power generated per square meter of area varies enormously. As of 2014, the largest solar thermal power systems using parabolic trough technology include the 354 MW SEGS plants in California, the 280 MW Solana Generating Station with molten salt heat storage , the 250 MW Genesis Solar Energy Project , the Spanish 200 MW Solaben Solar Power Station, and

3920-448: The average temperature difference between summer and winter in location — will also change over time because the Earth's axial tilt fluctuates between 22.1 and 24.5 degrees. Smaller irregularities in the times are caused by perturbations of the Moon and the other planets. Solar timing is based on insolation in which the solstices and equinoxes are seen as the midpoints of the seasons. This was

4000-634: The calculation of Easter) is 21 March, the same date as in the Easter tables current at the time of the Council of Nicaea in AD 325. The calendar is therefore framed to prevent the astronomical equinox wandering onto 22 March. From Nicaea to the date of the reform, the years 500, 600, 700, 900, 1000, 1100, 1300, 1400, and 1500, which would not have been leap years in the Gregorian calendar, amount to nine extra days, but astronomers directed that ten days be removed. Because of this,

4080-596: The case with the seasons described by the Roman scholar Varro (see above). It was the method for reckoning seasons in medieval Europe, especially by the Celts , and is still ceremonially observed in Ireland and some East Asian countries. Summer is defined as the quarter of the year with the greatest insolation and winter as the quarter with the least. The solar seasons change at the cross-quarter days, which are about 3–4 weeks earlier than

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4160-434: The century "leap year" rules of the Gregorian calendar); as 2000 was a leap year, the current shift has been progressing since the beginning of the last century, when equinoxes and solstices were relatively late. This also means that in many years of the twentieth century, the dates March 21, June 22, September 23, and December 22 were much more common, so older books teach (and older people may still remember) these dates. All

4240-500: The defined limit for seven consecutive days. (In Sweden the number of days ranges from 5 to 7 depending on the season.) This implies two things: The India Meteorological Department (IMD) designates four climatological seasons: In China, a common temperature-based reckoning holds that it is winter for the period when temperatures are below 10°C on average and summer for the period when temperatures are above 22°C on average. This means that areas with relatively extreme climates (such as

4320-469: The glasshouse structure. Steam is generated directly using oil field-quality water, as water flows along the length of the pipes, without heat exchangers or intermediate working fluids. The steam produced is then fed directly to the field's existing steam distribution network, where the steam is continuously injected deep into the oil reservoir. Sheltering the mirrors from the wind allows them to achieve higher temperatures and prevents dust from building up as

4400-512: The hemisphere faces the Sun. For the Southern Hemisphere it is instead in November, December, and January. It is Earth's axial tilt that causes the Sun to be higher in the sky during the summer months , which increases the solar flux . Due to seasonal lag , June, July, and August are the warmest months in the Northern Hemisphere while December, January, and February are the warmest months in

4480-543: The human race can receive unlimited power from the rays of the sun. Commercial plants using parabolic troughs may use thermal storage at night while some are hybrids and support natural gas as a secondary fuel source. In the United States the amount of fossil fuel used in order for the plant to qualify as a renewable energy source is limited to a maximum 27% of electricity production. Because they include cooling stations, condensers , accumulators and other things besides

4560-432: The ice on rivers and lakes. The Noongar people of South-West Western Australia recognise maar-keyen bonar, or six seasons. Each season's arrival is heralded not by a calendar date, but by environmental factors such as changing winds, flowering plants, temperature and migration patterns and lasts approximately two standard calendar months. The seasons also correlate to aspects of the human condition, intrinsically linking

4640-477: The lives of the people to the world that surrounds them and also dictating their movements, as with each season, various parts of country would be visited which were particularly abundant or safe from the elements. In the tropics, where seasonal dates also vary, it is more common to speak of the rainy (or wet, or monsoon ) season versus the dry season . For example, in Nicaragua the dry season (November to April)

4720-529: The meteorological and astronomical seasons. Oceanic regions tend to experience the beginning of the hibernal season up to a month later than continental climates . Conversely, prevernal and vernal seasons begin up to a month earlier near oceanic and coastal areas. For example, prevernal crocus blooms typically appear as early as February in coastal areas of British Columbia , the British Isles , but generally do not appear until March or April in locations like

4800-521: The meteorological seasons and 6–7 weeks earlier than seasons starting at equinoxes and solstices. Thus, the day of greatest insolation is designated "midsummer" as noted in William Shakespeare 's play A Midsummer Night's Dream , which is set on the summer solstice. On the Celtic calendar , the start of the seasons corresponds to four Pagan agricultural festivals - the traditional first day of winter

4880-528: The number of seasons between summer and winter can number from one to three. The dates are fixed at even intervals of months. In the Hindu calendar of tropical and subtropical India, there are six seasons or Ritu that are calendar-based in the sense of having fixed dates: Vasanta (spring), Grishma (summer), Varsha ( monsoon ), Sharada (autumn), Hemanta (early winter), and Shishira (prevernal or late winter). The six seasons are ascribed to two months each of

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4960-472: The outbreak of World War I and the discovery of cheap oil in the 1930s discouraged the advancement of solar energy, Shuman's vision and basic design were resurrected in the 1970s with a new wave of interest in solar thermal energy. In 1916 Shuman was quoted in the media advocating solar energy's utilization, saying: We have proved the commercial profit of sun power in the tropics and have more particularly proved that after our stores of oil and coal are exhausted

5040-409: The overall efficiency of the collector due to the sunlight striking the collectors at an angle but only requires the trough to be aligned with the change in seasons , avoiding the need for tracking motors. This tracking method approaches theoretical efficiencies at the spring and fall equinoxes with less accurate focusing of the light at other times during the year. The daily motion of the sun across

5120-449: The polar and temperate zones of one hemisphere is opposite to that of the other. When it is summer in the Northern Hemisphere, it is winter in the Southern, and vice versa. The tropical and (to a lesser degree) subtropical regions see little annual fluctuation of sunlight and temperature due to Earth's moderate 23.4-degree tilt being insufficient to appreciably affect the strength of the sun's rays annually. The slight differences between

5200-466: The respective solstice or equinox. Astronomically, the seasons are said to begin on Lichun ( 立春 , "the start of spring") on about 4 February, Lixia ( 立夏 ) on about 6 May, Liqiu ( 立秋 ) on about 8 August, and Lidong ( 立冬 ) on about 8 November. This system forms the basis of other such systems in East Asian lunisolar calendars. Some calendars in south Asia use a six-season partition where

5280-592: The result of the variation in Earth's distance to the Sun because of its elliptical orbit . In fact, Earth reaches perihelion (the point in its orbit closest to the Sun) in January, and it reaches aphelion (the point farthest from the Sun) in July, so the slight contribution of orbital eccentricity opposes the temperature trends of the seasons in the Northern Hemisphere. In general, the effect of orbital eccentricity on Earth's seasons

5360-411: The seasons ecologically by observing the activity of the plants, animals and weather around them. Each separate tribal group traditionally observes different seasons determined according to local criteria that can vary from the hibernation of polar bears on the arctic tundras to the growing seasons of plants in the tropical rainforests. In Australia, some tribes have up to eight seasons in a year, as do

5440-450: The seasons is determined by the exact times of the sun reaching the tropics of Cancer and Capricorn for the solstices and the times of the sun's transit over the equator for the equinoxes , or a traditional date close to these times. The following diagram shows the relation between the line of solstice and the line of apsides of Earth's elliptical orbit. The orbital ellipse (with eccentricity exaggerated for effect) goes through each of

5520-483: The six Earth images, which are sequentially the perihelion (periapsis—nearest point to the sun) on anywhere from 2 January to 5 January, the point of March equinox on 19, 20 or 21 March, the point of June solstice on 20 or 21 June, the aphelion (apoapsis—farthest point from the sun) on anywhere from 3 July to 6 July, the September equinox on 22 or 23 September, and the December solstice on 21 or 22 December. These "astronomical" seasons are not of equal length, because of

5600-427: The sky also introduces errors, greatest at the sunrise and sunset and smallest at noon. Due to these sources of error, seasonally adjusted parabolic troughs are generally designed with a lower concentration acceptance product . Parabolic trough concentrators have a simple geometry, but their concentration is about 1/3 of the theoretical maximum for the same acceptance angle , that is, for the same overall tolerances of

5680-449: The solar thermal system within a greenhouse-like glasshouse. The glasshouse creates a protected environment to withstand the elements that can increase the reliability and efficiency of the solar thermal system. Lightweight curved solar-reflecting mirrors are suspended within the glasshouse. A single-axis tracking system positions the mirrors to track the sun and focus its light onto a network of stationary steel pipes, also suspended from

5760-477: The solstices and the equinoxes cause seasonal shifts along a rainy low-pressure belt called the Intertropical Convergence Zone (ICZ). As a result, the amount of precipitation tends to vary more dramatically than the average temperature. When the ICZ is north of the Equator, the northern tropics experience their wet season while the southern tropics have their dry season. This pattern reverses when

5840-425: The system to all kinds of errors, including those referenced above. The theoretical maximum is better achieved with more elaborate concentrators based on primary-secondary designs using nonimaging optics which may nearly double the concentration of conventional parabolic troughs and are used to improve practical designs such as those with fixed receivers. Heat transfer fluid (usually thermal oil ) runs through

5920-413: The temperate zone that occupies all of New Zealand , New South Wales , Victoria , Tasmania , the south-eastern corner of South Australia and the south-west of Western Australia, and the south east Queensland areas south of Brisbane . In Sweden and Finland, meteorologists and news outlets use the concept of thermal seasons, which are defined based on mean daily temperatures. The beginning of spring

6000-517: The times are given in UTC (roughly speaking, the time at Greenwich , ignoring British Summer Time ). People living farther to the east (Asia and Australia), whose local times are in advance, see the astronomical seasons apparently start later; for example, in Tonga (UTC+13), an equinox occurred on September 24, 1999, a date on which the equinox will not fall again until 2103. On the other hand, people living far to

6080-401: The tube to absorb the concentrated sunlight. This increases the temperature of the fluid to some 400 °C. The heat transfer fluid is then used to heat steam in a standard turbine generator. The process is economical and, for heating the pipe, thermal efficiency ranges from 60 to 80%. The overall efficiency from collector to grid, i.e. (Electrical Output Power)/(Total Impinging Solar Power)

6160-550: The twelve months in the Hindu calendar. The rough correspondences are: The Bengali Calendar is similar but differs in start and end times. It has the following seasons or ritu: The Odia Calendar is similar but differs in start and end times. The Tamil calendar follows a similar pattern of six seasons Ecologically speaking, a season is a period of the year in which only certain types of floral and animal events happen (e.g.: flowers bloom—spring; hedgehogs hibernate—winter). So, if

6240-470: The west (America), whose clocks run behind UTC, may experience an equinox as early as March 19. Over thousands of years, the Earth's axial tilt and orbital eccentricity vary (see Milankovitch cycles ). The equinoxes and solstices move westward relative to the stars while the perihelion and aphelion move eastward. Thus, ten thousand years from now Earth's northern winter will occur at aphelion and northern summer at perihelion. The severity of seasonal change —

6320-590: Was a joint venture between Brightsource and Alstom . The station was the tallest solar power tower in the world at a height of 260 meters including the boiler but was recently surpassed by the 262.44 meter tall solar power tower at the Mohammed bin Rashid Al Maktoum Solar Park . Ashalim Plot C is a 30 MW photovoltaic plant, commissioned in 2018, one year before the CSP plants. In 2019 EDF Renewables won

6400-408: Was able to assign the dates of February 7, May 9, August 11, and November 10 to the start of spring, summer, autumn, and winter. As noted, a variety of dates and even exact times are used in different countries or regions to mark changes of the calendar seasons. These observances are often declared "official" within their respective areas by the local or national media, even when the weather or climate

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