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72-431: Currently, many sections of the expressway are still under construction. The sections of the expressways that are complete are: The route passes through the following cities: Baotou , Ordos , Yulin , Yan'an , Tongchuan , Xi'an , Ankang , Dazhou , Chongqing , Qianjiang , Jishou , Huaihua , Guilin , Wuzhou , Maoming Due to the challenging terrain the expressway includes numerous tunnels and bridges including

144-626: A city came relatively late, being incorporated as a town in 1809. The city's site was chosen because it was in an arable region of the Yellow River 's Great Bend. The Gelaohui secret society and the Hui Muslim General Ma Fuxiang came to an agreement in 1922, in which Ma Fuxiang agreed to allow the Gelaohui to extort protection money from wool merchants in Baotou. A railway from Beijing

216-550: A close approximation to UT1 , UTC occasionally has discontinuities where it changes from one linear function of TAI to another. These discontinuities take the form of leap seconds implemented by a UTC day of irregular length. Discontinuities in UTC occurred only at the end of June or December. However, there is provision for them to happen at the end of March and September as well as a second preference. The International Earth Rotation and Reference Systems Service (IERS) tracks and publishes

288-453: A mean solar day in the mid‑19th century. In earlier centuries, the mean solar day was shorter than 86,400 SI seconds, and in more recent centuries it is longer than 86,400 seconds. Near the end of the 20th century, the length of the mean solar day (also known simply as "length of day" or "LOD") was approximately 86,400.0013 s. For this reason, UT is now "slower" than TAI by the difference (or "excess" LOD) of 1.3 ms/day. The excess of

360-418: A mean solar day to lengthen by one second (at a rate of 2 ms per century). This rate fluctuates within the range of 1.7–2.3 ms/cy. While the rate due to tidal friction alone is about 2.3 ms/cy, the uplift of Canada and Scandinavia by several metres since the last ice age has temporarily reduced this to 1.7 ms/cy over the last 2,700 years. The correct reason for leap seconds, then,

432-474: A meridian drifting eastward faster and faster. Thus, the time system will lose its fixed connection to the geographic coordinates based on the IERS meridian . The difference between UTC and UT would reach 0.5 hours after the year 2600 and 6.5 hours around 4600. ITU-R Study Group 7 and Working Party 7A were unable to reach consensus on whether to advance the proposal to the 2012 Radiocommunications Assembly;

504-422: A minute is usually 60, but with an occasional leap second , it may be 61 or 59 instead. Thus, in the UTC time scale, the second and all smaller time units (millisecond, microsecond, etc.) are of constant duration, but the minute and all larger time units (hour, day, week, etc.) are of variable duration. Decisions to introduce a leap second are announced at least six months in advance in "Bulletin C" produced by

576-513: A particular time zone can be determined by adding or subtracting the number of hours and minutes specified by the UTC offset , which ranges from UTC−12:00 in the west to UTC+14:00 in the east (see List of UTC offsets ). The time zone using UTC is sometimes denoted UTC+00:00 or by the letter Z —a reference to the equivalent nautical time zone (GMT), which has been denoted by a Z since about 1950. Time zones were identified by successive letters of

648-662: A result of the International Telecommunication Union and the International Astronomical Union wanting to use the same abbreviation in all languages. The compromise that emerged was UTC , which conforms to the pattern for the abbreviations of the variants of Universal Time (UT0, UT1, UT2, UT1R, etc.). McCarthy described the origin of the abbreviation: In 1967 the CCIR adopted the names Coordinated Universal Time and Temps Universel Coordonné for

720-547: A shift of the sun's movements relative to civil time, with the difference increasing quadratically with time (i.e., proportional to elapsed centuries squared). This is analogous to the shift of seasons relative to the yearly calendar that results from the calendar year not precisely matching the tropical year length. This would be a change in civil timekeeping, and would have a slow effect at first, but becoming drastic over several centuries. UTC (and TAI) would be more and more ahead of UT; it would coincide with local mean time along

792-469: A source of error). UTC does not change with a change of seasons, but local time or civil time may change if a time zone jurisdiction observes daylight saving time (summer time). For example, local time on the east coast of the United States is five hours behind UTC during winter, but four hours behind while daylight saving is observed there. In 1928, the term Universal Time ( UT ) was introduced by

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864-442: A standard clock not on the geoid, or in rapid motion, will not maintain synchronicity with UTC. Therefore, telemetry from clocks with a known relation to the geoid is used to provide UTC when required, on locations such as those of spacecraft. It is impossible to compute the exact time interval elapsed between two UTC timestamps without consulting a table showing how many leap seconds occurred during that interval. By extension, it

936-482: A time standard. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up in many time zones. UTC divides time into days, hours, minutes, and seconds . Days are conventionally identified using the Gregorian calendar , but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes. The number of seconds in

1008-470: A total population of 2,709,378 accounting for counties under its jurisdiction. The city's namesake, literally translated to "place with deer", is of Mongolic origin or "Lucheng" ( Chinese : 鹿城 ; pinyin : Lùchéng ), meaning "City of Deer". Alternatively Baotou is known as the "City of Steel in Gobi" ( 草原钢城 ; Cǎoyuán Gāngchéng ). Steel was a major industry in the city. Today, Baotou refines over half of

1080-420: A value to be chosen for the length of the atomic second that would accord with the celestial laws of motion. The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted in 1963 as CCIR Recommendation 374, Standard-Frequency and Time-Signal Emissions , and "UTC" became the official abbreviation of Coordinated Universal Time in 1967. In 1961,

1152-448: Is male , and 49.3% is female . As of 2020, there are approximately 1,026,400 floating residents of Baotou, that is, residents of the city with a hukou registration elsewhere. This population has increased by 144,100, or 22.37%, since 2010. As of the 2020 Census, 2,334,400 people, or 86.16% of the city's population, lives in urban areas. The remaining 375,000 people, 13.84% of the city's population, lives in rural areas. Baotou

1224-448: Is affected by the leap seconds introduced in UTC). Time zones are usually defined as differing from UTC by an integer number of hours, although the laws of each jurisdiction would have to be consulted if sub-second accuracy was required. Several jurisdictions have established time zones that differ by an odd integer number of half-hours or quarter-hours from UT1 or UTC. Current civil time in

1296-468: Is aged 60 and older, 1.49 percentage points above the Chinese national average of 18.70%. 13.70% of Baotou's population is aged 65 and older, 0.20 percentage points above the Chinese national average of 13.50%. The number of people aged 60 and older has grown by 7.42% since 2010, and the number of people aged 65 and older has grown by 4.88% during that same span. Per the census, 50.7% of the city's population

1368-532: Is an abbreviation for the time laboratory. The time of events may be provisionally recorded against one of these approximations; later corrections may be applied using the International Bureau of Weights and Measures (BIPM) monthly publication of tables of differences between canonical TAI/UTC and TAI( k )/UTC( k ) as estimated in real-time by participating laboratories. (See the article on International Atomic Time for details.) Because of time dilation ,

1440-401: Is an accepted version of this page Coordinated Universal Time ( UTC ) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones . UTC facilitates international communication, navigation, scientific research, and commerce. UTC has been widely embraced by most countries and is

1512-478: Is approximately +1.7 ms per century. At the end of the 21st century, LOD will be roughly 86,400.004 s, requiring leap seconds every 250 days. Over several centuries, the frequency of leap seconds will become problematic. A change in the trend of the UT1 – UTC values was seen beginning around June 2019 in which instead of slowing down (with leap seconds to keep the difference between UT1 and UTC less than 0.9 seconds)

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1584-529: Is approximately 300 millimetres (11.8 in), with more than half of it falling in July and August alone. Due to the aridity and elevation, temperature differences between day and night can be large, especially in spring. In 2002, there were 12 instances of dust storms . Temperature extremes recorded since 1951 range from −31.4 °C (−25 °F) (though an unofficial record low of −32.8 °C (−27 °F) on 23 December 1935) to 40.4 °C (105 °F). Baotou

1656-924: Is divided into 10 county-level divisions, including 7 districts, 1 county and 2 banners. Direct-administered municipalities . Sub-provincial cities as provincial capitals . Separate state-planning cities . Special economic-zone cities . Open coastal cities . Prefecture capital status established by Heilongjiang Province and not recognized by Ministry of Civil Affairs. Disputed by Oroqen Autonomous Banner , Hulunbuir, Inner Mongolia as part of it. Only administers islands and waters in South China Sea and have no urban core comparable to typical cities in China. The claimed province of Taiwan no longer have any internal division announced by Ministry of Civil Affairs of PRC, due to lack of actual jurisdiction. See Template:Administrative divisions of Taiwan instead. UTC This

1728-732: Is located in the west of Inner Mongolia, located at the junction of two economic zones: the Bohai Economic Rim and the Upper Yellow River Natural Resources Enrichment Zone ( 黄河上游资源富集区 ). Its administrative area borders Mongolia's Dornogovi Province to the north, while the Yellow River, which flows for 214 kilometres (133 mi) in the prefecture, is south of the urban area itself. The Tumochuan Plateau ( 土默川平原 ), Hetao Plateau , and Yin Mountains cross

1800-485: Is not possible to compute the precise duration of a time interval that ends in the future and may encompass an unknown number of leap seconds (for example, the number of TAI seconds between "now" and 2099-12-31 23:59:59). Therefore, many scientific applications that require precise measurement of long (multi-year) intervals use TAI instead. TAI is also commonly used by systems that cannot handle leap seconds. GPS time always remains exactly 19 seconds behind TAI (neither system

1872-407: Is not the current difference between actual and nominal LOD, but rather the accumulation of this difference over a period of time: Near the end of the 20th century, this difference was about ⁠ 1 / 800 ⁠ of a second per day; therefore, after about 800 days, it accumulated to 1 second (and a leap second was then added). In the graph of DUT1 above, the excess of LOD above

1944-493: Is one of the "156 projects", which were constructed with the help of the Soviet Union to develop China's national economy in the 1950s and 1960s, and it continues this reputation until this day. Until the middle of the 1960s, the steel complex at Baotou was one of the rare examples of industrialization in the periphery of China. On 3 May 1996, at 03:32AM UTC (11:32AM local time ), an earthquake of M S 6.4 occurred. Since

2016-413: Is slightly longer than 86,400 SI seconds so occasionally the last minute of a UTC day is adjusted to have 61 seconds. The extra second is called a leap second. It accounts for the grand total of the extra length (about 2 milliseconds each) of all the mean solar days since the previous leap second. The last minute of a UTC day is permitted to contain 59 seconds to cover the remote possibility of

2088-463: Is very slowly decreasing because of tidal deceleration ; this increases the length of the mean solar day . The length of the SI ;second was calibrated on the basis of the second of ephemeris time and can now be seen to have a relationship with the mean solar day observed between 1750 and 1892, analysed by Simon Newcomb . As a result, the SI second is close to ⁠ 1 / 86400 ⁠ of

2160-532: The Aizhai Bridge which spans over 1 km. Note: italic indicates the routes that were available in 2013 network plan, but removed in 2022 network plan Baotou Baotou is the largest city by urban population in Inner Mongolia , China. Governed as a prefecture-level city , as of the 2020 census, its built-up ( or metro ) area made up of its 5 urban districts is home to 2,261,089 people with

2232-567: The Alxa League . Baotou was under Japanese control from 1937 until 1945. On September 19, 1949, after the September 19 Rebellion, Baotou fell under Communist control. The People's Government was formed in February 1950. In the early Communist years, Baotou served as an industrial centre, with a significant portion of its economy coming from its steel production. The Iron and Steel Base in Baotou

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2304-570: The Bureau International de l'Heure began coordinating the UTC process internationally (but the name Coordinated Universal Time was not formally adopted by the International Astronomical Union until 1967). From then on, there were time steps every few months, and frequency changes at the end of each year. The jumps increased in size to 0.1 seconds. This UTC was intended to permit a very close approximation to UT2. In 1967,

2376-558: The International Earth Rotation and Reference Systems Service . The leap seconds cannot be predicted far in advance due to the unpredictable rate of the rotation of Earth. Nearly all UTC days contain exactly 86,400 SI seconds with exactly 60 seconds in each minute. UTC is within about one second of mean solar time (such as UT1 ) at 0° longitude , (at the IERS Reference Meridian ). The mean solar day

2448-537: The SI second was redefined in terms of the frequency supplied by a caesium atomic clock. The length of second so defined was practically equal to the second of ephemeris time. This was the frequency that had been provisionally used in TAI since 1958. It was soon decided that having two types of second with different lengths, namely the UTC second and the SI second used in TAI, was a bad idea. It

2520-920: The UT1 variant of universal time . See the " Current number of leap seconds " section for the number of leap seconds inserted to date. The first leap second occurred on 30 June 1972. Since then, leap seconds have occurred on average about once every 19 months, always on 30 June or 31 December. As of July 2022 , there have been 27 leap seconds in total, all positive, putting UTC 37 seconds behind TAI. A study published in March 2024 in Nature concluded that accelerated melting of ice in Greenland and Antarctica due to climate change has decreased Earth's rotational velocity, affecting UTC adjustments and causing problems for computer networks that rely on UTC. Earth's rotational speed

2592-604: The WWV time signals, named for the shortwave radio station that broadcasts them. In 1960, the U.S. Naval Observatory, the Royal Greenwich Observatory, and the UK National Physical Laboratory coordinated their radio broadcasts so that time steps and frequency changes were coordinated, and the resulting time scale was informally referred to as "Coordinated Universal Time". In a controversial decision,

2664-405: The Yellow River by raft and boat from Lanzhou to Baotou, and shipped from Baotou by rail to the east (in particular, to Tianjin for export). The river traffic was one-way only, however, as the fast current made sailing up the Yellow River impractical. To travel from Baotou back to Lanzhou or Yinchuan , one would use a cart and camel road. There were also caravan roads from Baotou to Ordos and

2736-575: The 25th century, four leap seconds are projected to be required every year, so the current quarterly options would be insufficient. In April 2001, Rob Seaman of the National Optical Astronomy Observatory proposed that leap seconds be allowed to be added monthly rather than twice yearly. In 2022 a resolution was adopted by the General Conference on Weights and Measures to redefine UTC and abolish leap seconds, but keep

2808-699: The Baotou Municipal Government was awarded by UN-HABITAT for the improvements in shelter and the urban environments. In the early 21st century, Baotou's economy grew rapidly, growing about tenfold from 2000 to 2010. The city's gross domestic product peaked at about 386.763 billion renminbi (RMB) in 2016, and has shrunk significantly since then. Baotou is the largest economy of the Inner Mongolia Autonomous Region, and accounted for approximately 21.3% of Inner Mongolia 's total gross domestic product (GDP) as of 2012. As of 2018,

2880-599: The DUT1 correction (UT1 − UTC) for applications requiring a closer approximation of UT1 than UTC now provided. The current version of UTC is defined by International Telecommunication Union Recommendation (ITU-R TF.460-6), Standard-frequency and time-signal emissions , and is based on International Atomic Time (TAI) with leap seconds added at irregular intervals to compensate for the accumulated difference between TAI and time measured by Earth's rotation . Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of

2952-505: The Earth rotating faster, but that has not yet been necessary. The irregular day lengths mean fractional Julian days do not work properly with UTC. Since 1972, UTC may be calculated by subtracting the accumulated leap seconds from International Atomic Time (TAI), which is a coordinate time scale tracking notional proper time on the rotating surface of the Earth (the geoid ). In order to maintain

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3024-547: The Earth's rotation has sped up, causing this difference to increase. If the trend continues, a negative leap second may be required, which has not been used before. This may not be needed until 2025. Some time in the 22nd century, two leap seconds will be required every year. The current practice of only allowing leap seconds in June and December will be insufficient to maintain a difference of less than 1 second, and it might be decided to introduce leap seconds in March and September. In

3096-507: The English and French names with the acronym UTC to be used in both languages. The name "Coordinated Universal Time (UTC)" was approved by a resolution of IAU Commissions 4 and 31 at the 13th General Assembly in 1967 (Trans. IAU, 1968). Time zones around the world are expressed using positive, zero, or negative offsets from UTC , as in the list of time zones by UTC offset . The westernmost time zone uses UTC−12 , being twelve hours behind UTC;

3168-540: The International Astronomical Union to refer to GMT, with the day starting at midnight. Until the 1950s, broadcast time signals were based on UT, and hence on the rotation of the Earth. In 1955, the caesium atomic clock was invented. This provided a form of timekeeping that was both more stable and more convenient than astronomical observations. In 1956, the U.S.  National Bureau of Standards and U.S. Naval Observatory started to develop atomic frequency time scales; by 1959, these time scales were used in generating

3240-503: The LOD over the nominal 86,400 s accumulates over time, causing the UTC day, initially synchronised with the mean sun, to become desynchronised and run ahead of it. Near the end of the 20th century, with the LOD at 1.3 ms above the nominal value, UTC ran faster than UT by 1.3 ms per day, getting a second ahead roughly every 800 days. Thus, leap seconds were inserted at approximately this interval, retarding UTC to keep it synchronised in

3312-455: The UTC second equal to the TAI second. This CCIR Recommendation 460 "stated that (a) carrier frequencies and time intervals should be maintained constant and should correspond to the definition of the SI second ; (b) step adjustments, when necessary, should be exactly 1 s to maintain approximate agreement with Universal Time (UT); and (c) standard signals should contain information on the difference between UTC and UT." As an intermediate step at

3384-561: The UTC system. If only milliseconds precision is needed, clients can obtain the current UTC from a number of official internet UTC servers. For sub-microsecond precision, clients can obtain the time from satellite signals. UTC is also the time standard used in aviation , e.g. for flight plans and air traffic control . In this context it is frequently referred to as Zulu time, as described below. Weather forecasts and maps all use UTC to avoid confusion about time zones and daylight saving time. The International Space Station also uses UTC as

3456-551: The alphabet and the Greenwich time zone was marked by a Z as it was the point of origin. The letter also refers to the "zone description" of zero hours, which has been used since 1920 (see time zone history ). Since the NATO phonetic alphabet word for Z is "Zulu", UTC is sometimes known as "Zulu time". This is especially true in aviation, where "Zulu" is the universal standard. This ensures that all pilots, regardless of location, are using

3528-544: The chairman of Study Group 7 elected to advance the question to the 2012 Radiocommunications Assembly (20 January 2012), but consideration of the proposal was postponed by the ITU until the World Radio Conference in 2015. This conference, in turn, considered the question, but no permanent decision was reached; it only chose to engage in further study with the goal of reconsideration in 2023. A proposed alternative to

3600-408: The city's GDP is 295.180 billion renminbi (RMB), a 7.22% increase from the previous year, but much lower than the city's peak of 386.763 billion RMB in 2016. Baotou's secondary sector has proven crucial to the city's economy. As of 2016, it contributed 182.215 RMB to the city's economy, 47.11% of the city's total GDP. However, like the city's total economy, it has shrunk since then. As of 2020,

3672-411: The city's secondary sector contributed 115.300 billion RMB to Baotou's economy. Baotou Xingsheng Economic & Technological Development Zone is an industrial zone in Baotou. As noted, in the early Communist years Baotou served as an industrial centre, with a significant portion of its economy coming from its industry around metals, mostly steel. The Iron and Steel Base of Bautou was constructed with

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3744-441: The civil second constant and equal to the SI second, so that sundials would slowly get further and further out of sync with civil time. The leap seconds will be eliminated by 2035. The resolution does not break the connection between UTC and UT1, but increases the maximum allowable difference. The details of what the maximum difference will be and how corrections will be implemented is left for future discussions. This will result in

3816-551: The currently used prime meridian , and is not adjusted for daylight saving time . The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted as a standard in 1963 and "UTC" became the official abbreviation of Coordinated Universal Time in 1967. The current version of UTC is defined by the International Telecommunication Union . Since adoption, UTC has been adjusted several times, notably adding leap seconds in 1972. Recent years have seen significant developments in

3888-473: The difference between UTC and Universal Time, DUT1 = UT1 − UTC, and introduces discontinuities into UTC to keep DUT1 in the interval (−0.9 s, +0.9 s). As with TAI, UTC is only known with the highest precision in retrospect. Users who require an approximation in real time must obtain it from a time laboratory, which disseminates an approximation using techniques such as GPS or radio time signals . Such approximations are designated UTC( k ), where k

3960-541: The easternmost time zone uses UTC+14 , being fourteen hours ahead of UTC. In 1995, the island nation of Kiribati moved those of its atolls in the Line Islands from UTC−10 to UTC+14 so that Kiribati would all be on the same day. UTC is used in many Internet and World Wide Web standards. The Network Time Protocol (NTP), designed to synchronise the clocks of computers over the Internet, transmits time information from

4032-438: The effective successor to Greenwich Mean Time (GMT) in everyday usage and common applications. In specialized domains such as scientific research, navigation, and timekeeping, other standards such as UT1 and International Atomic Time (TAI) are also used alongside UTC. UTC is based on TAI, which is a weighted average of hundreds of atomic clocks worldwide. UTC is within about one second of mean solar time at 0° longitude,

4104-483: The end of 1971, there was a final irregular jump of exactly 0.107758 TAI seconds, making the total of all the small time steps and frequency shifts in UTC or TAI during 1958–1971 exactly ten seconds, so that 1 January 1972 00:00:00 UTC was 1 January 1972 00:00:10 TAI exactly, and a whole number of seconds thereafter. At the same time, the tick rate of UTC was changed to exactly match TAI. UTC also started to track UT1 rather than UT2. Some time signals started to broadcast

4176-402: The epicenter of the earthquake was located close to the city, Baotou was very damaged by the earthquake: 26 people were killed, 453 injured and 196,633 lost their homes. The electrical infrastructure of the city was also damaged, and soil liquefaction occurred around the swamps of the Yellow River . The earthquake, which destroyed many old houses, led to the reconstruction of Baotou. In 2002,

4248-509: The frequency for the caesium transition , newly established, with the ephemeris second . The ephemeris second is a unit in the system of time that, when used as the independent variable in the laws of motion that govern the movement of the planets and moons in the solar system, enables the laws of motion to accurately predict the observed positions of solar system bodies. Within the limits of observable accuracy, ephemeris seconds are of constant length, as are atomic seconds. This publication allowed

4320-399: The frequency of the signals was initially set to match the rate of UT, but then kept at the same frequency by the use of atomic clocks and deliberately allowed to drift away from UT. When the divergence grew significantly, the signal was phase shifted (stepped) by 20 ms to bring it back into agreement with UT. Twenty-nine such steps were used before 1960. In 1958, data was published linking

4392-673: The help of the Soviet Union to help China in developing its economy; it was one of the 156 Projects that the Soviets helped build for that purpose in the 1950s and 1960s. Baotou is a major center for rare-earth metals. Rare-earth minerals from the Bayan Obo Mining District , about 120 kilometres from Baotou, are processed in the city. They are used in many electrical and electronic devices, such as smartphones, TVs, wind turbines, and electric vehicle motors. The toxic byproducts from

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4464-435: The long term. The actual rotational period varies on unpredictable factors such as tectonic motion and has to be observed, rather than computed. Just as adding a leap day every four years does not mean the year is getting longer by one day every four years, the insertion of a leap second every 800 days does not indicate that the mean solar day is getting longer by a second every 800 days. It will take about 50,000 years for

4536-494: The nominal 86,400 s corresponds to the downward slope of the graph between vertical segments. (The slope became shallower in the 1980s, 2000s and late 2010s to 2020s because of slight accelerations of Earth's rotation temporarily shortening the day.) Vertical position on the graph corresponds to the accumulation of this difference over time, and the vertical segments correspond to leap seconds introduced to match this accumulated difference. Leap seconds are timed to keep DUT1 within

4608-505: The rare-earth minerals produced in the world. This has led to environmental contamination near the industrial sites. The area now known as Baotou was inhabited by nomads, some of whose descendants would later be categorized as Mongols. Near the end of the Han dynasty —206 BC–220 AD— Lü Bu , a particularly noteworthy warrior, was born in today's Jiuyuan District of Baotou. Compared to the capital of Inner Mongolia, Hohhot , Baotou's construction as

4680-416: The realm of UTC, particularly in discussions about eliminating leap seconds from the timekeeping system because leap seconds occasionally disrupt timekeeping systems worldwide. The General Conference on Weights and Measures adopted a resolution to alter UTC with a new system that would eliminate leap seconds by 2035. The official abbreviation for Coordinated Universal Time is UTC . This abbreviation comes as

4752-517: The refineries are contained by the Baotou Tailings Dam . According to the 2020 Chinese Census , Baotou has a permanent population of about 2,709,400 people, up about 59,000 from the 2010 Census . The average household in Baotou comprises 2.27 people, down from 2.65 as of 2010. Baotou, like many places in China , has an aging population . As per the 2020 Census, 20.19% of Baotou's population

4824-629: The same 24-hour clock , thus avoiding confusion when flying between time zones. See the list of military time zones for letters used in addition to Z in qualifying time zones other than Greenwich. On electronic devices which only allow the time zone to be configured using maps or city names, UTC can be selected indirectly by selecting cities such as Accra in Ghana or Reykjavík in Iceland as they are always on UTC and do not currently use daylight saving time (which Greenwich and London do, and so could be

4896-467: The urban area and central part of the prefecture. Baotou City ranges in latitude from 41° 20' to 42° 40' N and in longitude from 109° 50' to 111° 25' E. Baotou features a cold semi-arid climate ( Köppen BSk ), marked by long, cold and very dry winters, hot, somewhat humid summers, and strong winds, especially in spring. Temperatures often fall below −15 °C (5 °F) in winter and rise above 30 °C (86 °F) in summer. The annual precipitation

4968-489: The vertical range depicted by the adjacent graph. The frequency of leap seconds therefore corresponds to the slope of the diagonal graph segments, and thus to the excess LOD. Time periods when the slope reverses direction (slopes upwards, not the vertical segments) are times when the excess LOD is negative, that is, when the LOD is below 86,400 s. As the Earth's rotation continues to slow, positive leap seconds will be required more frequently. The long-term rate of change of LOD

5040-408: Was also dissatisfaction with the frequent jumps in UTC (and SAT). In 1968, Louis Essen , the inventor of the caesium atomic clock, and G. M. R. Winkler both independently proposed that steps should be of 1 second only. to simplify future adjustments. This system was eventually approved as leap seconds in a new UTC in 1970 and implemented in 1972, along with the idea of maintaining

5112-549: Was constructed in 1923, and the city began spurring some industrial sites. A German-Chinese joint-venture in 1934 constructed the Baotou Airport and opened a weekly route connecting Baotou with Ningxia and Lanzhou . When young Owen Lattimore visited Baotou in 1925, it was still "a little husk of a town in a great hollow shell of mud ramparts, where two busy streets made a traders' quarter", but already an important railhead. Qinghai and Gansu wool and hides were brought down

5184-408: Was thought better for time signals to maintain a consistent frequency, and that this frequency should match the SI second. Thus it would be necessary to rely on time steps alone to maintain the approximation of UT. This was tried experimentally in a service known as "Stepped Atomic Time" (SAT), which ticked at the same rate as TAI and used jumps of 0.2 seconds to stay synchronised with UT2. There

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