A cenote ( English: / s ɪ ˈ n oʊ t i / or / s ɛ ˈ n oʊ t eɪ / ; Latin American Spanish: [seˈnote] ) is a natural pit , or sinkhole , resulting when a collapse of limestone bedrock exposes groundwater . The term originated on the Yucatán Peninsula of Mexico, where the ancient Maya commonly used cenotes for water supplies, and occasionally for sacrificial offerings . The name derives from a word used by the lowland Yucatec Maya — tsʼonoʼot —to refer to any location with accessible groundwater.
87-581: In Mexico the Yucatán Peninsula alone has an estimated 10,000 cenotes, water-filled sinkholes naturally formed by the collapse of limestone, and located across the peninsula. Some of these cenotes are at risk from the construction of the new tourist Maya Train . Cenotes are common geological forms in low-altitude regions, particularly on islands (such as Cefalonia, Greece), coastlines, and platforms with young post- Paleozoic limestone with little soil development. The term cenote , originally applying only to
174-517: A "blurring" effect in the resulting light, as it would no longer be travelling in just one direction. But this effect is not seen in nature. A correct explanation rests on light's nature as an electromagnetic wave . Because light is an oscillating electrical/magnetic wave, light traveling in a medium causes the electrically charged electrons of the material to also oscillate. (The material's protons also oscillate but as they are around 2000 times more massive, their movement and therefore their effect,
261-519: A capacity of 47 passengers, they only have a capacity of 18. These 7 buses, built by BYD Auto , arrived at the airport in March 2024. Environmental and indigenous rights activists objected to construction of new tracks through the jungle. On the 26th anniversary of its armed uprising, January 1, 2020, the Zapatista Army of National Liberation expressed its opposition to the project and declared that
348-448: A cavern dive into a cave dive. Contrary to cenote cavern diving, cenote cave diving requires special equipment and training (certification for cave diving). However, both cavern and cave diving require detailed briefings, diving experience, and weight adjustment to freshwater buoyancy. The cenotes are usually filled with rather cool fresh water. Cenote divers must be wary of possible halocline ; this produces blurred vision until they reach
435-415: A given pair of media, the ratio of the sines of the angle of incidence θ 1 {\displaystyle {\theta _{1}}} and angle of refraction θ 2 {\displaystyle {\theta _{2}}} is equal to the ratio of phase velocities v 1 v 2 {\textstyle {\frac {v_{1}}{v_{2}}}} in
522-647: A hacienda 8 km (5.0 mi) away. They said that by 2025 the station will relocate to La Plancha Park in Mérida. Construction began in June 2020. The construction companies are Mota-Engil México SAPI and China Communications Construction Company LTD for stretch one (Palenque-Escárcega), Operadora CICSA and FCC Construcción for stretch two (Escárcega-Calkiní), Construcciones Urales and GAMI Ingeniería e Instalaciones for stretch three (Calkiní-Izamal), and Grupo ICA for stretch four (Izamal–Cancún). In September 2020 Fonatur rejected
609-416: A list of the longest and deepest water-filled and dry caves within the state boundaries. When cavern diving, one must be able to see natural light the entire time that one is exploring the cavern (e.g., Kukulkan cenote near Tulum , Mexico). During a cave dive, one passes the point where daylight can penetrate, and one follows a safety guideline to exit the cave. Things change quite dramatically once moving from
696-404: A more fundamental way be derived from the 2 or 3-dimensional wave equation . The boundary condition at the interface will then require the tangential component of the wave vector to be identical on the two sides of the interface. Since the magnitude of the wave vector depend on the wave speed this requires a change in direction of the wave vector. The relevant wave speed in the discussion above
783-611: A more homogeneous area. Cave dive sites: Tren Maya February 29, 2024 (Cancún–Playa del Carmen) The Tren Maya ( Yucatec Maya : Tsíimin K'áak' , sometimes also Mayan Train or Maya Train ) is a 1,554 km-long (966 mi) intercity railway in Mexico that traverses the Yucatán Peninsula . Construction began in June 2020 and the Campeche–Cancún section began operation on December 15, 2023, with
870-677: A planned extension to Progreso and Umán in Yucatán. Funding for the project will come primarily from a tourism tax levied in the region, as well as funds diverted from other programs, including the Mexican Grand Prix . The project, led by the National Fund for Tourism Development [ es ] (Fonatur), in December 2018 was estimated to cost 150 billion pesos (US$ 7.4 billion) and attract 8,000 daily riders. An alternative study by
957-460: A proposal of investment firm BlackRock for the 125 km (78 mi) fifth stretch of the project, including improvements to the Tulum–Cancún highway. In February 2021 Fonatur awarded a contract to Acciona and Grupo México for 60.3 km (37.5 mi) of electrified double rail tracks for section five between Playa del Carmen and Tulum. 75% of the 121 km (75 mi) section five
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#17328514671691044-497: A public policy think tank in 2019 estimated the cost of the project would be 480 billion pesos (US$ 25.3 billion), supported by the 90 percent cost overrun on the Toluca–Mexico City commuter rail project. In October 2021 Fonatur revised the construction estimate to 200 billion pesos. In October 2020 the estimated total cost of the project, including 30 years of operating and maintenance but not including electrification,
1131-507: A referendum on the Mayan Train would be held on December 15, 2019, in Chiapas, Tabasco, Campeche, Yucatán, and Quintana Roo. The weekend of December 15–16, 2019, 92.3% of the people who participated in the consultation voted in favor, while 7.4% voted against the proposal. 100,940 people voted, 2.36% of the 3,536,000 registered voters in the 84 municipalities affected. The Mexican Office of
1218-493: A region of a different speed. The amount of ray bending is dependent on the amount of difference between sound speeds, that is, the variation in temperature, salinity, and pressure of the water. Similar acoustics effects are also found in the Earth's atmosphere . The phenomenon of refraction of sound in the atmosphere has been known for centuries. Beginning in the early 1970s, widespread analysis of this effect came into vogue through
1305-470: A rock overhanging above the water. The stereotypical cenotes often resemble small circular ponds , measuring some tens of meters in diameter with sheer rock walls. Most cenotes, however, require some degree of stooping or crawling to access the water. In the north and northwest of the Yucatán Peninsula in Mexico, the cenotes generally overlie vertical voids penetrating 50 to 100 m (160 to 330 ft) below
1392-432: A section of Sistema Aktun Hu (part of Sistema Sac Actun ) known as the pit Hoyo Negro . At a depth of 57 m (187 ft) the divers located the remains of a mastodon and a human skull (at 43 m [141 ft]) that might be the oldest evidence of human habitation in the region. The Yucatán Peninsula has almost no rivers and only a few lakes, and those are often marshy. The widely distributed cenotes are
1479-426: A shoreline tend to strike the shore close to a perpendicular angle. As the waves travel from deep water into shallower water near the shore, they are refracted from their original direction of travel to an angle more normal to the shoreline. In underwater acoustics , refraction is the bending or curving of a sound ray that results when the ray passes through a sound speed gradient from a region of one sound speed to
1566-410: A slower rate. The light has effectively been slowed. When the light leaves the material, this interaction with electrons no longer happens, and therefore the wave packet rate (and therefore its speed) return to normal. Consider a wave going from one material to another where its speed is slower as in the figure. If it reaches the interface between the materials at an angle one side of the wave will reach
1653-414: A straight object, such as a pencil in the figure here, which is placed at a slant, partially in the water, the object appears to bend at the water's surface. This is due to the bending of light rays as they move from the water to the air. Once the rays reach the eye, the eye traces them back as straight lines (lines of sight). The lines of sight (shown as dashed lines) intersect at a higher position than where
1740-422: A sunny day when using high magnification telephoto lenses and is often limiting the image quality in these cases. In a similar way, atmospheric turbulence gives rapidly varying distortions in the images of astronomical telescopes limiting the resolution of terrestrial telescopes not using adaptive optics or other techniques for overcoming these atmospheric distortions . Air temperature variations close to
1827-536: A temporary delay in construction in January 2021 until Fonatur and SEMARNAT report on an environmental impact assessment . On March 3, 2021, an injunction was filed by 80 people from Campeche who fear eviction from their homes. The First District Court in Campeche granted them the provisional suspension. Yucatán's fourth district court also ordered a stop to construction. The brought the total number of injunctions filed in
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#17328514671691914-411: A vast coastal aquifer system, which is typically density-stratified. The infiltrating meteoric water (i.e., rainwater) floats on top of higher- density saline water intruding from the coastal margins. The whole aquifer is therefore an anchialine system (one that is land-locked but connected to an ocean). Where a cenote, or the flooded cave to which it is an opening, provides deep enough access into
2001-627: A year, the line is intended to redistribute tourist flows that are currently concentrated on the coast, and to encourage the development of a region that has historically been neglected by the state. The Tren Maya project was announced in September 2018 by Mexican president-elect Andrés Manuel López Obrador , following earlier proposals to build a shorter 900-kilometre (560 mi) line. Previous presidential administrations had also proposed their own passenger rail projects, but were unsuccessful in attaining funding. It would use existing right of way from
2088-441: Is 10 to 20 m (33 to 66 ft) below the water table at the coast, and 50 to 100 m (160 to 330 ft) below the water table in the middle of the peninsula, with saline water underlying the whole of the peninsula. In 1936, a simple morphometry-based classification system for cenotes was presented. The classification scheme was based on morphometric observations above the water table, and therefore incompletely reflects
2175-553: Is a clinical test in which a phoropter may be used by the appropriate eye care professional to determine the eye's refractive error and the best corrective lenses to be prescribed. A series of test lenses in graded optical powers or focal lengths are presented to determine which provides the sharpest, clearest vision. Refractive surgery is a medical procedure to treat common vision disorders. Water waves travel slower in shallower water. This can be used to demonstrate refraction in ripple tanks and also explains why waves on
2262-409: Is also responsible for rainbows and for the splitting of white light into a rainbow-spectrum as it passes through a glass prism . Glass and water have higher refractive indexes than air. When a beam of white light passes from air into a material having an index of refraction that varies with frequency (and wavelength), a phenomenon known as dispersion occurs, in which different coloured components of
2349-596: Is elevated and built as viaduct to protect the ground water. As of January 2021 plans call for diesel-electric trains running at up to 160 km/h (100 mph). In May 2021 Fonatur contracted with a consortium headed by Alstom to supply rolling stock and related equipment. The rolling stock will be manufactured at Alstom's factory in Ciudad Sahagún . The contract also includes European Train Control System signalling and control equipment. López Obrador has said
2436-418: Is far smaller). A moving electrical charge emits electromagnetic waves of its own. The electromagnetic waves emitted by the oscillating electrons interact with the electromagnetic waves that make up the original light, similar to water waves on a pond, a process known as constructive interference . When two waves interfere in this way, the resulting "combined" wave may have wave packets that pass an observer at
2523-418: Is the phase velocity of the wave. This is typically close to the group velocity which can be seen as the truer speed of a wave, but when they differ it is important to use the phase velocity in all calculations relating to refraction. A wave traveling perpendicular to a boundary, i.e. having its wavefronts parallel to the boundary, will not change direction even if the speed of the wave changes. Refraction
2610-642: Is therefore associated with the mass extinction of the non-avian dinosaurs and is also known as the Cretaceous–Paleogene extinction event . In 2001–2002 expeditions led by Arturo H. González and Carmen Rojas Sandoval in the Yucatán discovered three human skeletons; one of them, Eve of Naharon , was carbon-dated to be 13,600 years old. In March 2008, three members of the Proyecto Espeleológico de Tulum and Global Underwater Explorers dive team, Alex Alvarez, Franco Attolini, and Alberto Nava, explored
2697-692: The Chichén Itzá railway station opened in February 2024 and the Valladolid railway station was expected to open further on. The rolling stock of the Tren Maya was designed by the French company Alstom , and its 219 cars were being built in Ciudad Sahagún . Of these trains, 32 of them will be electro-diesel multiple units , 10 will be standard diesel multiple units . Regular passenger service will be provided by
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2784-503: The Ferrosur as well as new tracks constructed through the jungle. The project was derided by political opposition groups as a stunt for López Obrador, who had also cancelled a major airport project in Mexico City favored by his predecessor. The Zapatista Army of National Liberation announced that it would oppose the project. On November 15, 2019, President López Obrador declared that
2871-682: The UNESCO Convention on the Protection of the Underwater Cultural Heritage . Cenotes have attracted cavern and cave divers, and there are organized efforts to explore and map these underwater systems. They are public or private and sometimes considered "National Natural Parks". Great care should be taken to avoid spoiling this fragile ecosystem when diving. In Mexico, the Quintana Roo Speleological Survey maintains
2958-474: The Xiinbal train, named for a Mayan term meaning “to walk”, as the regular passenger service. They will have business class seats, standard seating, and a buffet car . This service will be offered to frequent local passengers, but also to occasional passengers and tourists. The Janal trains (from a Mayan term meaning "to eat") will add a dining car to the previous services, which will have aquatic landscapes on
3045-414: The human eye . The refractive index of materials varies with the wavelength of light, and thus the angle of the refraction also varies correspondingly. This is called dispersion and causes prisms and rainbows to divide white light into its constituent spectral colors . A correct explanation of refraction involves two separate parts, both a result of the wave nature of light. As described above,
3132-519: The speed of light is slower in a medium other than vacuum. This slowing applies to any medium such as air, water, or glass, and is responsible for phenomena such as refraction. When light leaves the medium and returns to a vacuum, and ignoring any effects of gravity , its speed returns to the usual speed of light in vacuum, c . Common explanations for this slowing, based upon the idea of light scattering from, or being absorbed and re-emitted by atoms, are both incorrect. Explanations like these would cause
3219-652: The Jaguar has identified twelve wildlife corridors that could be constructed to mitigate the situation for the jaguars that live in the area. The Centro Mexicano de Derecho Ambiental environmental group has accused Fonatur of deforestation along the route, not accounted for in the environmental impact assessment and without acquiring the necessary permits. In November 2021 the Interior Department exempted Tren Maya and other infrastructure projects from environmental review. Original plans called for electric locomotives on
3306-645: The Sacred Cenote there in 1904. He discovered human skeletons and sacrificial objects confirming a local legend, the Cult of the Cenote , involving human sacrifice to the rain god Chaac by the ritual casting of victims and objects into the cenote. However, not all cenotes were sites of human sacrifice. The cenote at Punta Laguna has been extensively studied and none of the approximately 120 individuals show signs of sacrifice. The remains of this cultural heritage are protected by
3393-487: The United Nations High Commissioner for Human Rights criticized the vote. They pointed out that voters were provided with only the positive effects of the project (improved attention to water supplies, health, education, employment, housing, environmental protection, and culture) but were not informed of the negative effects. The Human Rights Commission also criticized the translations of the material used,
3480-471: The Yucatan Peninsula to 16 in March 2021, increasing to at least 25 by January 2022. Most of the injunctions have been filed by indigenous collectives who consider the project to be an environmental disaster. Court rulings are not binding on Tren Maya because it has been declared a national security project. The injunctions have had little effect, and construction continues. López Obrador has criticized
3567-400: The actual rays originated. This causes the pencil to appear higher and the water to appear shallower than it really is. The depth that the water appears to be when viewed from above is known as the apparent depth . This is an important consideration for spearfishing from the surface because it will make the target fish appear to be in a different place, and the fisher must aim lower to catch
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3654-465: The afterlife, and home to the rain god, Chaac . The Maya often deposited human remains as well as ceremonial artifacts in these cenotes. The discovery of golden sacrificial artifacts in some cenotes led to the archaeological exploration of most cenotes in the first part of the 20th century. Edward Herbert Thompson (1857–1935), an American diplomat who had bought the Chichen Itza site, began dredging
3741-415: The air density and thus vary with air temperature and pressure . Since the pressure is lower at higher altitudes, the refractive index is also lower, causing light rays to refract towards the earth surface when traveling long distances through the atmosphere. This shifts the apparent positions of stars slightly when they are close to the horizon and makes the sun visible before it geometrically rises above
3828-405: The apparent depth approaches zero, albeit reflection increases, which limits observation at high angles of incidence. Conversely, the apparent height approaches infinity as the angle of incidence (from below) increases, but even earlier, as the angle of total internal reflection is approached, albeit the image also fades from view as this limit is approached. The refractive index of air depends on
3915-403: The aquifer, the interface between the fresh and saline water may be reached. The density interface between the fresh and saline waters is a halocline , which means a sharp change in salt concentration over a small change in depth. Mixing of the fresh and saline water results in a blurry swirling effect caused by refraction between the different densities of fresh and saline waters. The depth of
4002-633: The authorities. The route of the track was modified several times to take into account the demands of environmentalists. Before starting work, the Ministry of the Environment carried out an inventory of flora and fauna, and relocated animals to protected areas. The Mexican Center for Environmental Law (Cemda), however, denounces a project which, in its entirety, has destroyed "2,500 hectares of tropical rainforest" and directly affected twenty protected natural areas. Residents of 130 localities directly affected by
4089-487: The cave roof have collapsed revealing an underlying cave system, and the water flow rates may be much faster: up to 10 kilometers (6 mi) per day. The Yucatan cenotes attract cavern and cave divers who have documented extensive flooded cave systems, some of which have been explored for lengths of 376 km (234 mi) or more. Cenotes are formed by the dissolution of rock and the resulting subsurface void, which may or may not be linked to an active cave system , and
4176-413: The cenotes Choo-Ha , Tankach-Ha, and Multum-Ha near Tulum . There are at least 6,000 cenotes in the Yucatán Peninsula of Mexico. Cenote water is often very clear, as the water comes from rain water filtering slowly through the ground, and therefore contains very little suspended particulate matter. The groundwater flow rate within a cenote may be very slow. In many cases, cenotes are areas where sections of
4263-555: The consultation provided only positive information to voters prior to voting. Groups close to the National Indigenous Congress (CNI) plan to seek injunctions against the train project and other construction in the region. The CNI is looking at three-pronged action: social awareness campaigns, media campaigns, and legal actions. On January 28, 2020, a judge in Campeche issued a temporary injunction against construction of
4350-746: The features in Yucatán, has since been applied by researchers to similar karst features in other places such as in Cuba , Australia , Europe , and the United States . Cenotes are surface connections to subterranean water bodies. While the best-known cenotes are large open-water pools measuring tens of meters in diameter, such as those at Chichen Itza in Mexico , the greatest number of cenotes are smaller sheltered sites and do not necessarily have any surface exposed water. Some cenotes are only found through small <1 m (3 ft) diameter holes created by tree roots, with human access through enlarged holes, such as
4437-433: The fish. Conversely, an object above the water has a higher apparent height when viewed from below the water. The opposite correction must be made by an archer fish . For small angles of incidence (measured from the normal, when sin θ is approximately the same as tan θ ), the ratio of apparent to real depth is the ratio of the refractive indexes of air to that of water. But, as the angle of incidence approaches 90°,
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#17328514671694524-411: The halocline is a function of several factors: climate and specifically how much meteoric water recharges the aquifer, hydraulic conductivity of the host rock, distribution and connectivity of existing cave systems, and how effective these are at draining water to the coast, and the distance from the coast. In general, the halocline is deeper further from the coast, and in the Yucatán Peninsula this depth
4611-441: The horizon during a sunrise. Temperature variations in the air can also cause refraction of light. This can be seen as a heat haze when hot and cold air is mixed e.g. over a fire, in engine exhaust, or when opening a window on a cold day. This makes objects viewed through the mixed air appear to shimmer or move around randomly as the hot and cold air moves. This effect is also visible from normal variations in air temperature during
4698-518: The implications of the Maya Train, opposition to the project "is above all a media campaign, driven by a few collectives, but it is by no means a social movement. They have no popular support." The vast majority of the population of the states concerned seem to support the Mayan Train. As of January 2021, workers and archeologists had uncovered more than 8,000 ancient artifacts and structures during construction. The National Alliance for Conservation of
4785-427: The law of refraction is typically written as n 1 sin θ 1 = n 2 sin θ 2 . {\displaystyle n_{1}\sin \theta _{1}=n_{2}\sin \theta _{2}\,.} Refraction occurs when light goes through a water surface since water has a refractive index of 1.33 and air has a refractive index of about 1. Looking at
4872-531: The line, including eight ex- China Railway DF-4D locomotives owned by Chinese contractors, some Vossloh G2000 BB locomotives, and "older locomotives imported secondhand from Europe". The Conexión Intermodal Tren Maya is a future set of 3 electric shuttle bus connections in Cancun , Puerto Morelos , and Playa del Carmen that will link to the Tren Maya. Two lines will connect Puerto Morelos and Playa del Carmen stations with different tourist attractions of
4959-510: The measured rim of the Chicxulub crater . This crater structure, identified from the alignment of cenotes, but also subsequently mapped using geophysical methods (including gravity mapping ) and also drilled into with core recovery, has been dated to the boundary between the Cretaceous and Paleogene geologic periods, 66 million years ago. This meteorite impact at the Cretaceous–Paleogene boundary
5046-530: The military would own the entire route, not just the three sections, and would receive all of the profits. According to the government, "the use of Sedena [Mexico's Ministry of Defense] guarantees good administration and prevents the risk of privatization", in a country known for corruption. Pons stated in September 2021 that the cost of a single trip for locals, for the section that goes from Cancún Airport to Playa del Carmen , will be around 50 pesos. Tourists will be expected to pay between 800 and 1000 pesos for
5133-590: The modern water table. However, very few of these cenotes appear to be connected with horizontally extensive underground river systems, with water flow through them being more likely dominated by aquifer matrix and fracture flows. In contrast, the cenotes along the Caribbean coast of the Yucatán Peninsula (within the state of Quintana Roo ) often provide access to extensive underwater cave systems, such as Sistema Ox Bel Ha , Sistema Sac Actun / Sistema Nohoch Nah Chich and Sistema Dos Ojos . The Yucatán Peninsula contains
5220-406: The most secluded and darker cenotes, the fauna has evolved to resemble those of many cave-dwelling species. For example, many animals don't have pigmentation and are often blind, so they are equipped with long feelers to find food and make their way around in the dark. Although cenotes are found widely throughout much of the Yucatán Peninsula, a higher-density circular alignment of cenotes overlies
5307-537: The only perennial source of potable water and have long been the principal source of water in much of the region. Major Maya settlements required access to adequate water supplies, and therefore cities, including the famous Chichen Itza , were built around these natural wells. Many cenotes like the Sacred Cenote in Chichen Itza played an important role in Maya rites. The Maya believed that cenotes were portals to Xibalba or
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#17328514671695394-444: The outside, and an interior inspired by the work of Luis Barragán . “The restaurant offers two layout options and various seating configurations to allow optimal use of space in a beautiful setting.” The P'atal trains (from a Mayan term meaning "to stay") will have reclining seats and sleeping cabins, designated especially for long-distance journeys. In addition, several locomotives have been imported to Mexico to help construct
5481-436: The processes by which the cenotes formed and the inherent hydrogeochemical relationship with the underlying flooded cave networks, which were only discovered in the 1980s and later with the initiation of cave diving exploration. Flora and fauna are generally scarcer than in the open ocean; however, marine animals do thrive in caves. In caverns, one can spot mojarras , mollies , guppies , catfish , small eels and frogs . In
5568-818: The project is anticipated to open in the late 2020s, but tourism officials in the region have proposed accelerating work for a 2023 opening. The route consists of seven sections. Section I runs 228 km (142 mi) from Palenque to Escárcega ; section II 235 km (146 mi) from Escárcega to Calkiní ; section III 172 km (107 mi) from Calkiní to Izamal ; section IV 257 km (160 mi) from Izamal to Cancún Airport; section V 121 km (75 mi) from Cancún Airport to Tulum ; section VI 254 km (158 mi) from Tulum to Bacalar ; and section VII 287 km (178 mi) from Bacalar to Escárcega. Business leaders in Mérida, Yucatán expressed their support on January 31, 2020, for building four kilometers of
5655-511: The project will be completed prior to the end of his term in 2024. A market survey conducted by Fonatur, PricewaterhouseCoopers and other consultants in 2019 found that a majority of 21 construction companies consider this too fast, an unreasonable time to construct so much new rail, and others have expressed fear of a disaster caused by substandard work, such as the May 2021 Mexico City Metro overpass collapse . In January 2022, to speed up construction,
5742-582: The railroad route will benefit from "388 worksites and social actions", including the rehabilitation of pavements and roads, public spaces, electrical, sanitary and productive infrastructures, and housing. For 150 mph (241 km/h) or more in the US, see High-speed rail in the United States Refraction In physics , refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by
5829-406: The railway because it was approved in a "simulated consultation." In a visit to the city of Campeche , President López Obrador defended the train and pointed out that not only had the train received its greatest support in the state of Campeche, but also that more than half the route would run through the state—worth MXN $ 60 billion of the $ 130 billion the government plans to invest in total. He said
5916-508: The railway underground as it passes through the city of Mérida. In this way, the train will not threaten the city's historic center. They are also optimistic that the tourist train, in combination with improvements in energy, airports, and seaports, will make the region economically competitive with the North and the Bajío . Fonatur later announced that the train would initially not stop in Mérida, but near
6003-589: The region, while a third will connect the Cancún Airport railway station with the 4 terminals of Cancun International Airport . Work on the Cancun Airport shuttle began in July 2023, and it was hoped that it would begin operations on 29 February. The Cancun shuttle bus will use 7 electric buses, which have a top speed of 69 kilometres per hour (43 mph). Although it was originally announced that they will have
6090-516: The rest of the line to open later. The railway begins in Cancún International Airport and travels southwest towards Palenque, Chiapas , via two routes that encircle the peninsula. The project aims to connect tourist destinations in the Caribbean with lesser-known sites inland, including historic Mayan sites from which it derives its name. By linking the main towns in the region, with 42 trains carrying up to three million passengers
6177-454: The route was changed to no longer enter Playa del Carmen. As of June 2021 , 10% of the project had been completed. This had increased to 25% by February 2022, and 67% by June 2023. Operations officially began on December 15, 2023. Operations on the line were suspended from December 28 to December 31, in preparation for the extension of service to Palenque . Service resumed on January 1, from Cancún Airport to Palenque. In addition,
6264-534: The saliency in opposition to the train as a partisan attempt to halt his administration's infrastructure projects. A group of celebrities, including comedian Eugenio Derbez , singers Rubén Albarrán and Natalia Lafourcade , and actress Kate del Castillo , as part of the Sélvame del Tren ("Save me from the Train", a play on words between Sálvame meaning Save Me, and Selva meaning jungle) campaign, has expressed opposition to
6351-417: The same thing is to consider the change in wavelength at the interface. When the wave goes from one material to another where the wave has a different speed v , the frequency f of the wave will stay the same, but the distance between wavefronts or wavelength λ = v / f will change. If the speed is decreased, such as in the figure to the right, the wavelength will also decrease. With an angle between
6438-422: The same trip. When explaining the difference in price, he stated that tourists will have additional services available, such as restaurants. On December 16, 2018, president López Obrador conducted a Mayan ritual to commemorate the start of construction on the Mayan Train project. The railway will also accommodate local passenger traffic and freight shipments in addition to tourist functions. The first phase of
6525-441: The second material first, and therefore slow down earlier. With one side of the wave going slower the whole wave will pivot towards that side. This is why a wave will bend away from the surface or toward the normal when going into a slower material. In the opposite case of a wave reaching a material where the speed is higher, one side of the wave will speed up and the wave will pivot away from that side. Another way of understanding
6612-690: The section from Escárcega to Cancún should be open for tourist, passenger, and freight traffic in 2023, but that the route will not pass through the Calakmul Biosphere Reserve . In November 2020 the Regional Indigenous Council of Xpujil delivered a petition with 268,000 signatures to the Campeche Ministry of Environment and Natural Resources asking that the project be suspended because of environmental concerns. Residents of Chocholá , Mérida, and Izamal , in Yucatán obtained
6699-437: The short period of time for the election, and low turnout, particularly among indigenous women. They noted that many potential voters did not have the financial resources to travel to the voting locations, and that the majority of voters were municipal employees. The government rejected the criticisms, stating the consultation met international standards. In June 2022 Interior Secretary Adán Augusto López Hernández announced
6786-454: The subsequent structural collapse. Rock that falls into the water below is slowly removed by further dissolution, creating space for more collapse blocks. Likely, the rate of collapse increases during periods when the water table is below the ceiling of the void since the rock ceiling is no longer buoyantly supported by the water in the void. Cenotes may be fully collapsed, creating an open water pool, or partially collapsed with some portion of
6873-418: The surface can give rise to other optical phenomena, such as mirages and Fata Morgana . Most commonly, air heated by a hot road on a sunny day deflects light approaching at a shallow angle towards a viewer. This makes the road appear reflecting, giving an illusion of water covering the road. In medicine , particularly optometry , ophthalmology and orthoptics , refraction (also known as refractometry )
6960-425: The train's impact on wildlife and the environment above ground and in caves. Urbina Bravo is also involved in a legal battle to halt construction. Segment number 5 of the Maya Train network has been the most contested by environmental associations. Stretching over 110 kilometers, its completion involved the deforestation of a continuous 60-meter-wide strip – that's 2.2 million trees "felled or displaced", according to
7047-404: The train. In July 2022 residents of Chemax barricaded surrounding roads, bringing construction to a halt. They say the government has violated its agreement by clearing the jungle and failing to provide promised infrastructure. However, according to Etienne von Bertrab, a specialist in political ecology at University College London (UCL) and co-founder of an interdisciplinary study group on
7134-583: The trains. In June 2020 the government announced a switch to diesel to reduce costs, then in August 2020 they announced that half the route, from Mérida to Chetumal via Cancún, would be electrified. In March 2022, Greenpeace organizers tied themselves to heavy machinery as a protest against construction in Quintana Roo that involves cutting down the jungle without environmental studies having been made. Cave diver Jose Urbina Bravo conducts expeditions to study
7221-593: The two media, or equivalently, to the refractive indices n 2 n 1 {\textstyle {\frac {n_{2}}{n_{1}}}} of the two media: sin θ 1 sin θ 2 = v 1 v 2 = n 2 n 1 {\displaystyle {\frac {\sin \theta _{1}}{\sin \theta _{2}}}={\frac {v_{1}}{v_{2}}}={\frac {n_{2}}{n_{1}}}} Optical prisms and lenses use refraction to redirect light, as does
7308-741: The wave fronts and the interface and change in distance between the wave fronts the angle must change over the interface to keep the wave fronts intact. From these considerations the relationship between the angle of incidence θ 1 , angle of transmission θ 2 and the wave speeds v 1 and v 2 in the two materials can be derived. This is the law of refraction or Snell's law and can be written as sin θ 1 sin θ 2 = v 1 v 2 . {\displaystyle {\frac {\sin \theta _{1}}{\sin \theta _{2}}}={\frac {v_{1}}{v_{2}}}\,.} The phenomenon of refraction can in
7395-438: The wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and water waves also experience refraction. How much a wave is refracted is determined by the change in wave speed and the initial direction of wave propagation relative to the direction of change in speed. For light, refraction follows Snell's law , which states that, for
7482-529: The white light are refracted at different angles, i.e., they bend by different amounts at the interface, so that they become separated. The different colors correspond to different frequencies and different wavelengths. For light, the refractive index n of a material is more often used than the wave phase speed v in the material. They are directly related through the speed of light in vacuum c as n = c v . {\displaystyle n={\frac {c}{v}}\,.} In optics , therefore,
7569-480: Was about 321 billion pesos. The Secretariat of Tourism will receive a 647.1% increase in its budget for 2021 (MXN $ 38,613.4 million), of which 94% is destined for the Mayan Train. In December 2020 president López Obrador announced that the armed forces would operate three sections of the route, and that profits would be used to strengthen finances for pensioners and retirees of the armed forces. In March 2021 Fonatur general director Rogelio Jiménez Pons said that
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