Summer time (abbreviated DST ), sometimes referred to as daylight savings time in US, Canadian, and Australian, and is known as < b> Summer time in some countries, is the practice of advancing hours during the summer months so that daylight lasts longer, while sacrificing normal sunrise time. Typically, areas that use summer time adjust the hour ahead one hour near the beginning of spring and adjust it backwards in autumn to standard time.
George Hudson proposed the idea of ​​daylight savings in 1895. The German and Austrian-Hungarian Empires organized the first national application, beginning on April 30, 1916. Many countries have used it at various times since then, especially since the energy crisis of the 1970s..
DST is generally not observed near the equator, where the sunrise time is not varied enough to justify it. Some countries only observe in some areas; for example, southern Brazil watches it while Brazilian equator does not. Only a small percentage of the world's population uses DST, as Asia and Africa generally do not observe it.
DST clock shifts sometimes make timeliness difficult and can disrupt travel, billing, record keeping, medical equipment, heavy equipment and sleep patterns. Computer software often adjusts the clock automatically, but policy changes by various date jurisdictions and DST timings may be confusing.
Video Daylight saving time
Rationale
Industrial societies generally follow a clock-based schedule for day-to-day activities that do not change throughout the year. The time when individuals start and end work or school, and the coordination of mass transportation, for example, usually remains constant throughout the year. In contrast, the daily routine of agrarian societies for work and personal behavior is more likely to be governed by the length of daylight and by the time of the sun, which changes seasonally due to the axis of the Earth's axis. The north and south of tropical afternoons last longer in summer and shorter in winter, with the greater the effect of getting away from the tropics.
By synchronizing all clocks in an area up to an hour earlier than standard time, individuals who follow such year-round schedules will wake up an hour earlier than they should be doing; they will start and complete their daily work routine an hour early, and they will be providing an additional hour an hour a day after their weekday activities. However, they will have an hour less during the day at the start of each day, making the policy less practical during the winter.
As sunrise and sunset times change at about the same rate as the season changes, Daylight Saving Time supporters argue that most people prefer a larger increase during the day after typical "nine to five" work hours. Proponents also argue that DST reduces energy consumption by reducing lighting and heating requirements, but the actual effect on overall energy use is strongly debated.
Time manipulation at higher latitudes (eg Iceland, Nunavut or Alaska) has little impact on everyday life, since the length of day and night changes more extreme throughout the season (compared to other latitudes), and thus the sun rises and sets times significantly out of phase with standard working hours regardless of clock manipulation. DST is also little used for locations near the equator, as the region only sees little variation during the day throughout the year. The effect also varies depending on how far east or west the location is in its time zone, with the farther east location within the time zone more advantageous than the DST rather than the farther west location in the same time zone.
Maps Daylight saving time
History
Although they do not fix their schedule to the clock in the modern sense, ancient civilizations adjust daily schedules to the sun more flexibly than DST, often dividing the day into twelve hours apart from daylight, so (for example) every hour of the day becomes progressively longer spring and shorter during autumn. For example, the Romans kept time with water clocks that had different scales for different months of the year: at the Roman latitude of the third hour of sunrise, hora tertia , beginning with the modern standard at 09: 02 sun time and lasts 44 minutes on the winter solstice, but on the summer solstice begins at 06:58 and lasts for 75 minutes. After ancient times, the same civilian hours ended up replacing the unequal, so the civil time no longer varied by season. Unequal clocks are still used in some traditional settings, such as some Athos mountain monasteries and all Jewish ceremonies.
During his time as an American envoy to France (1776-1785), Benjamin Franklin, publisher of the old English proverb "Early sleep, and early rising, made a man healthy, rich and wise", anonymously published a letter in the Journal de Paris states that Parisians conserve wax by rising earlier to use the morning sun. 1784 This satire proposes a window covering taxation, rationing of candles, and waking the public by ringing church bells and firing cannons at sunrise. Despite a common misconception, Franklin did not actually propose DST; 18th century Europe does not even maintain a proper schedule. However, this soon changed when the railway transport and communication networks required unknown time standardization in Franklin.
New Zealand entomologist George Hudson first proposed a modern DST. Hudson's work-time job gave her spare time to collect insects and guide her to appreciate the daylight outside work hours. In 1895 he presented a paper to the Wellington Philosophical Society proposing a two-hour shift, and after great interest was expressed in Christchurch, he followed up with a paper in 1898. Many publications gave DST proposals to the leading British builders and outsiders William Willett, who independently composed DST in 1905 during a pre-breakfast trip, as he watched anxiously how many Londoners slept through most of the summer day. Playing golfers, Willett also does not like cutting short rounds at dusk. The solution is to advance hours during the summer months, a proposal he published two years later. Liberal MP MP Robert Pearce took Willett's proposal, introducing the first Daylight Saving Bill to the House of Commons on February 12, 1908. A select committee was formed to examine the issue, but the Pearce bill was not legal, and several other bills failed in the year -next year. Willett lobbied for a proposal in England until his death in 1915.
William Sword Frost, mayor of Orillia, Ontario, introduced daylight saving time in the municipality during his tenure from 1911 to 1912.
Beginning April 30, 1916, the German Empire and its World War I, Austria-Hungary introduced DST (German: Sommerzeit ) as a way to preserve coal during wartime. Britain, most of its allies, and many European neutrons soon followed suit. Russia and several other countries waited until next year, and the United States adopted daylight saving in 1918.
Broadly speaking, most jurisdictions leave summer time in the years after the war ended in 1918 (with some exceptions including Canada, England, France, and Ireland). However, many different places adopted it over a period of time over the next decade and became common during World War II. It became widely adopted, particularly in North America and Europe, beginning in 1970 as a result of the energy crisis of the 1970s.
Since then, the world has seen many endorsements, adjustments, and repetitions. For specific details, see Summer time by country.
Procedures
In the United States, a one-hour time shift occurs at 2:00 am local time. In the spring hour jumps ahead of the last instant of 1:59 standard time up to 03:00 DST and the day has 23 hours. In autumn the clock jumps back from the last instant 1:59 DST to 1:00 standard time, repeats the clock, and the day has 25 hours. The digital display of local time does not read 2am right at the time of transfer to summer, but it jumps from 1:59 to 59.9 ahead to 03: 00: 00.0.
The clock shift is usually scheduled near midnight weekends to reduce disruptions to the weekday schedule. A one-hour shift is a habit. A twenty minute and two hour shift has been used in the past.
The coordination strategy differs when the adjacent time zone shifts the clock. The European Union shifts all zones at the same time, at 01:00 Greenwich Time or 2:00 CET or 3:00 EET. The result of this procedure is that Eastern European Time is always an hour earlier than Central European Time, with the cost of shifts occurring at different local times. In contrast, most of North America shifted at 2:00 pm local time, so the zones do not change at the same time; for example, Mountain Time is temporarily (for one hour) zero hours faster than Pacific Time, not an hour ahead, in autumn and two hours instead of one hour, ahead of Pacific Time in spring. In the past, Australian districts went even further and did not always agree on start and end dates; for example, in 2008 most of the DST observers shifted hours ahead on October 5, but Western Australia shifted on October 26. In some cases, only part of the country is shifting; for example, in the US, Hawaii, and most of Arizona does not observe DST.
Start and end dates vary by location and year. Since 1996, the European Summer Time has been observed from the last Sunday in March to the last Sunday in October; previously uniform regulations in the EU. Beginning in 2007, most of the United States and Canada observed DST from the second week of March to the first Sunday of November, almost two-thirds of the year. The 2007 US changes are part of the Energy Policy Act of 2005; earlier, from 1987 to 2006, the start and end dates are the first Sunday in April and the last Sunday in October, and Congress maintains the right to return to the previous date after energy consumption studies have been conducted. Supporters to defend permanently November as a month to end the DST point to Halloween as an excuse to delay the change - to provide extra daylight on October 31st.
The beginning and end date are roughly reversed in the southern hemisphere. For example, the Chilean mainland observes DST from the second Saturday in October to the second Saturday of March, with a transition at 24:00 local time.
As a result, the time difference between the two regions varies throughout the year due to DST. Central European times are typically six hours longer than East Time North America, except for a few weeks in March and October/November. Similarly, the United Kingdom and Chilean lands may be separated for five hours during the northern summer, three hours during the southern summer, and four hours several weeks per year due to incompatibility of the amendment date.
Politics
Daylight saving has caused controversy ever since it started. Winston Churchill argues that it magnifies "the opportunity to pursue health and happiness among millions of people living in this country" and experts have called it "Daylight Slaving Time". Historically, retail, sport, and tourism interests favored daylight savings, while the interest of agricultural and night entertainment has been against it, and its initial application has been driven by the energy and war crises.
The fate of Willett's proposal of 1907 illustrates some of the political issues involved. This proposal attracted many supporters, including Arthur Balfour, Churchill, David Lloyd George, Ramsay MacDonald, Edward VII (who used a half hour DST at Sandringham or "Sandringham time"), Harrods managing director, and manager of the National Bank. However, the opposition is stronger: it includes Prime Ministers H. H. Asquith, Christie (Astronomer Royal), George Darwin, Napier Shaw (director of the Meteorological Office), many agricultural organizations, and theater owners. After many hearings, the proposal was narrowly lost in a parliamentary committee vote in 1909. Willett's allies introduced a similar bill every year from 1911 to 1914, to no avail. The US is even more skeptical: Andrew Peters introduced the bill DST to the United States House of Representatives in May 1909, but soon died on the committee.
After Germany took the lead by initiating DST during World War I on 30 April 1916 together with its allies to alleviate the difficulties of the war of coal shortage and power outages, political equations changed in other countries; Britain used the first DST on May 21, 1916. The interests of US manufacturing and manufacturing led by Pittsburgh industrialist Robert Garland soon began lobbying the DST, but were opposed by the railroad tracks. US 1917 went into war over objections, and DST was founded in 1918.
The end of the war swings the pendulum back. Farmers continue to dislike DST, and many countries pull it out after the war. England is an exception: it maintains the DST nationally but over the years adjusts the transition dates for several reasons, including special rules during the 1920s and 1930s to avoid shifting hours on Easter morning. Now under the summer time the European Community directive starts every year on the last Sunday of March, which may be Easter Sunday (as of 2016). The US is more typical: Congress lifted DST after 1919. President Woodrow Wilson, like Willett, a diligent golfer, vetoed the strangulation twice but his second veto was imposed. Only a few US cities retain DST locally thereafter, including New York so that its financial markets can maintain an hour of arbitrage trading with London, and Chicago and Cleveland to follow New York. Successor Wilson Warren G. Harding opposes DST as "fraud". On the grounds that people should get up and go to work early in the summer, he ordered federal District of Columbia employees to start work at 8:00 rather than at 9:00 am during the summer of 1922. Some businesses follow although many others do not; experiment not repeated.
Since the adoption of Germany in 1916, the world has seen much of the legitimacy, adaptation, and repetition of DST, with similar political engagement.
The history of the time in the United States included DST during both world wars, but there was no standardized DST of peacetime until 1966. In May 1965, for two weeks, St. Paul, Minnesota and Minneapolis, Minnesota were at different times, when the capital decided to join most countries by starting Daylight Saving Time while Minneapolis chose to follow the later date set by state law. In the mid-1980s, Clorox (parent of Kingsford Charcoal) and 7-Eleven provided major funding for the Summer Time Coalition behind the 1987 extension to US DST, and both Idaho senators chose it on the premise that during fast DST - lots of fries, made from Idaho potatoes.
In 1992, after a three-year austerity austerity trial in Queensland, Australia, a referendum on daylight savings was held and was defeated with 54.5% 'no' votes - with regional and rural areas strongly opposed, while those in the metropolitan area south-east support. In 2005, the Association of Sporting Goods and National Association of Convenience Stores successfully lobbied for a 2007 extension to the US DST. In December 2008, Daylight Saving for South East Queensland (DS4SEQ) political party was officially registered in Queensland, advocating the adoption of double time zone settings for daylight saving in Southeast Queensland while other states maintained standard time. DS4SEQ competed for Queensland state elections in March 2009 with 32 candidates and received one percent of primary votes across the state, equating about 2.5% across all 32 contested electorates. After a three-year trial, over 55% of Western Australians voted against DST in 2009, with rural areas strongly opposed. On April 14, 2010, after being approached by the DS4SEQ political party, Queensland Independent member Peter Wellington introduced Daylight Saving for the Southeast Queensland Referendum Bill 2010 to the Queensland parliament, calling for a referendum on the next state election on daylight saving introduction to South East Queensland under zone settings double time. The bill was defeated in the Queensland parliament on June 15, 2011.
In Britain, the Royal Society for Prevention of Accidents supports the proposal to observe SDST's additional time throughout the year, but is opposed in some industries, such as postal workers and farmers, and especially by those living in northern England.
In some Muslim countries, DST is temporarily abandoned during Ramadan (the month when there is no food to eat between sunrise and sunset), because DST will postpone dinner. Ramadan occurs in July and August of 2012. This concerns at least Morocco, although Iran keeps DST during Ramadan. Most Muslim countries do not use DST, partly for this reason.
The 2011 declaration by Russia which will remain in DST throughout the year followed by a similar declaration from Belarus. The Russian plan raises many complaints due to the darkness of winter in the morning, and then abandoned in 2014. The country changed its clock to Standard Time on October 26, 2014 and intends to live there permanently.
Disputes of advantages and disadvantages
DST supporters generally argue that it saves energy, promotes outdoor recreational activities at night (in summer), and is therefore good for physical and psychological health, reducing traffic accidents, reducing crime or good for business. Groups that tend to support DST are urban workers, retail businesses, outdoor sports enthusiasts and businesses, tourism operators, and others who benefit from having more light hours after typical end of workday in the warmer months.
Opponents argue that actual energy savings can not be inferred, that DST increases health risks such as heart attacks, DST can interfere with morning activity, and that changing hourly action economically and socially interferes with and cancels any benefits. Farmers tend to oppose DST.
Having a common agreement about the layout or schedule of the day gives so many advantages that standard schedules across countries or large areas are generally chosen over an ad hoc effort where some people wake up early and others do not. The benefits of coordination are so great that many people ignore whether DSTs apply by altering their nominal work schedules to coordinate with television broadcasts or daylight. DST is generally not observed for much of winter, because the days are shorter; workers may not have sunlit time to spare, and students may need to go to school in the dark. Because DST is applied to many different communities, the effects may vary considerably depending on their culture, level of light, geography, and climate. Because of these variations, it is difficult to make general conclusions about the absolute effects of this exercise. Costs and benefits may vary from place to place. Some areas may adopt DST only as a matter of coordination with others rather than for any immediate benefit.
Energy usage
A 2017 meta-analysis of 44 studies found that DST leads to electricity savings of only 0.34% during the days when DSTs took effect. Further meta-analysis found that "greater electricity savings for countries farther away from the equator, while subtropical regions consume more electricity because of DST." This means DST can save electricity in some countries, such as Canada and the UK, but wasteful elsewhere, such as Mexico, the southern United States, and northern Africa. Electricity savings can also be offset by the extra use of other types of energy, such as heating fuel.
The Daylight Saving Time period before the longest day is shorter than the following period, in some countries including the United States and Europe. This unequal split is an energy-saving step. For example, in the US the Daylight Saving Time period is determined by the Energy Policy Act of 2005. The Summer Time Period The day is extended by changing the start date of the first week of April to the second week of March, and the end date of the last Sunday in October to the first Sunday in November.
The potential for DST to save energy comes primarily from its impact on residential lighting, which consumes about 3.5% of electricity in the United States and Canada. (By comparison, AC uses 16.5% of energy in the United States.) Delaying sunset and sunrise nominal time reduces the use of artificial light at night and increases it in the morning. As shown by susan Franklin 1784, the cost of illumination decreases if nighttime reductions exceed morning hikes, as in high latitudes when most people wake up after sunrise. The initial purpose of DST is to reduce the use of incandescent lights at night, once the main use of electricity. Although energy conservation remains an important goal, the pattern of energy use has changed greatly since then. The use of electricity is strongly influenced by geography, climate, and economy, so the results of research conducted in one place may be irrelevant to other countries or climates.
- In the United States, high-quality research shows that DST reduces the cost of home lighting but usually increases total energy consumption, especially when non-electric energy sources are considered. These non-electric energy consumption sources include extra heating fuel in colder, darker and extra gasoline used to drive to shopping and sports activities. In some cases, DST improves residential power consumption, such as when people use more air conditioning in longer and hotter nights.
- A 2007 study estimated that daylight savings in winter would prevent a 2% increase in average daily electricity consumption in the UK. This paper was revised in October 2009.
- In 2000, when parts of Australia began DST at the end of winter, overall electricity consumption was unchanged, but morning peak loads and prices increased. The overall consumption is the same because people use more electricity on dark mornings, and thus less electricity on a brighter night. In Western Australia during the summer of 2006-2007, DST increased electricity consumption during hotter days and lowered it during cold days, with consumption up 0.6% overall.
- Although a 2007 study predicted that introducing DST to Japan would reduce household energy consumption, the 2007 simulation estimated that DST would increase overall energy use in Osaka shelters by 0.13%, with a 0.02% decrease due to the illumination less than in excess of an increase of 0.15% due to extra cooling; no studies have examined the use of non-residential energy. This may be because the effect of DST on lighting energy usage is especially noticeable in residence.
Several studies have shown that DST increases motor fuel consumption. The DOE 2008 report found no significant increase in gasoline motor consumption due to DST expansion in the United States in 2007.
Economic effects
Unsupported DST winners are retailers, sporting goods makers, and other businesses that benefit from the extra afternoon sun. Having more hours of sunlight between typical end of work day and bedtime encourages customers to shop and participate in outdoor sports. People are more likely to stop by the shop on their way home from work if the sun is still up. In 1984, Fortune magazine estimated that a seven-week DST extension would result in an additional $ 30 million for a 7-Eleven store, and the National Golf Foundation estimated expansion would boost the golf industry's income by $ 200 million to $ 300 million. A 1999 study estimated that DST boosts the EU's recreation sector revenues by about 3%.
On the contrary, DST may harm some farmers, small children, who have difficulty getting enough sleep at night when the evening is sunny, and others whose clock is set by the sun. One of the reasons farmers are against DST is that grains are best harvested after the moisture evaporates, so when field hands arrive and leave early in the summer, their energy is less valuable. Dairy farmers are another group that complains of change. Their cows are sensitive to milking time, so milk delivery has previously disrupted their system. Today some farmer groups support DST.
DST also harms the ratings of prime-time television broadcasts, drive-ins and other theaters.
Changing clock and DST rules have direct economic costs, which involve extra work to support remote meetings, computer applications and the like. For example, a 2007 North American rule change cost about $ 500 million to $ 1 billion, and Utah State University economist William F. Shughart II estimates the lost opportunity cost of approximately US $ 1.7 billion. Although it has been argued that clock shifts correlate with a decrease in economic efficiency, and that in 2000 the daylight savings effect implies an estimated $ 31 billion one-day loss on US stock exchanges, the estimate of numbers depending on the methodology. The results have been disputed, and the original author has disputed the points raised by the disputed party.
Public security
In 1975, the US DOT conservatively identified a 0.7% decline in traffic deaths during DST, and estimated a real decline at 1.5% to 2%, but the NBS review in 1976 from the DOT study found no difference in traffic deaths. In 1995, the Insurance Institute for Highway Safety estimated a 1.2% reduction, including a 5% reduction in fatal accident for pedestrians. Others have found similar reductions. Single/Double Summer Time (SDST), a variant of one hour in front of the sun in winter and two hours in summer, has been projected to reduce traffic deaths by 3% to 4% in the UK, compared to regular DST. However, accidents increased by 11% over the two weeks following the end of the British Summer Time. It is unclear whether sleep disorders contribute to fatal accidents soon after the spring hour shifts. Correlations between shifting hours and traffic accidents have been observed in North America and the UK but not in Finland or Sweden. If this effect exists, it is much smaller than the overall reduction in traffic deaths. A US study in 2009 found that on Monday after switching to DST, workers slept an average of 40 minutes less, and were more often injured in the workplace and more severely.
DST is likely to reduce some types of crimes, such as robbery and sexual harassment, as fewer potential victims are out of doors after dusk. Artificial outdoor lighting has a marginal and sometimes even contradictory effect on crime and fear of evil.
In some countries, fire safety officers encourage citizens to use two yearly shift hours as a reminder to replace batteries in smoke and carbon monoxide detectors, especially in autumn, just before the heating season and wax leads to an increase in house fires. Similar two-year tasks include reviewing and practicing fire extinguishers and family disaster plans, checking vehicle lights, checking storage areas for hazardous materials, reprogramming thermostats, and seasonal vaccinations. Locations without DST can use the first days of spring and fall as a reminder.
A study in 2017 at the American Economic Journal: Applied Economics estimates that "the transition to DST causes more than 30 deaths at a social cost of $ 275 million per year," primarily by increasing sleep deprivation.
Health
DST has a mixed effect on health. In a community with a fixed work schedule, it provides more afternoon sun for outdoor exercise. It alters sun exposure; whether this is beneficial depends on the location and daily schedule of a person, because sunlight triggers the synthesis of vitamin D in the skin, but excess exposure can cause skin cancer. DST can help in depression by causing individuals to rise earlier, but some argue otherwise. Retinitis Pigmentosa Foundation Fighting Blindness, headed by blind sporting monarch Gordon Gund, successfully lobbied in 1985 and 2005 for the US DST extension. DST shifts are associated with higher rates of ischemic stroke within the first two days after the shift, although not in the following week.
Clock shifts are found to increase the risk of heart attack by up to 10 percent, and disrupt sleep and reduce its efficiency. The effects on the seasonal adaptation of circadian rhythms can be severe and last for weeks. A 2008 study found that although the rate of male suicide increased in the weeks following the spring shift, the relationship was greatly weakened after adjusting for the season. A 2008 Swedish study found that heart attacks were significantly more common in the first three working days after the spring transition, and significantly less common on the first business day after the autumn transition. A 2013 review found little evidence that people slept much more on the night following a decrease in DST, although it is often described as allowing people to sleep for an hour longer than normal. The same reviews suggest that sleep hours lost by spring shifts seem to result in sleep loss at least a week later. By 2015, two psychologists suggest that DST be eliminated, citing the disturbing effects on sleep as one of the reasons for this recommendation.
The Kazakh government cited health complications as the hours shifted as an excuse to abolish the DST in 2005. In March 2011, Dmitri Medvedev, president of Russia, claimed that "stress hour changes" were a motivation for Russia to remain in DST throughout the year. long. Officials at the time were talking about an increase in suicide each year.
The unexpected adverse effects of summer time may lie in the fact that an additional part of the morning rush hour traffic before dawn and traffic emissions then causes higher air pollution than during the day.
In 2017, researchers at the University of Washington and the University of Virginia report that judges who suffer from sleep deprivation due to DST tend to issue longer sentences.
Complexity and Loss
The clock shift of DST has a real drawback of complexity. People should remember to change their clock; this can be time consuming, especially for mechanical clocks that can not be moved backward safely. People working across time zone boundaries need to keep track of some DST rules, as not all locations observe DST or observe them in the same way. Calendar day length becomes variable; no longer always 24 hours. Distractions at meetings, trips, broadcasts, billing systems, and records management are common, and can be expensive. During the autumn transition from 02:00 to 01:00, a clock reads the time from 01:00:00 to 01:59:59 twice, which may cause confusion.
Damage to the German steel facility occurred during the DST transition in 1993, when the computer time system connected to the radio timing synchronization signal allowed the molten steel to cool for an hour less than the required duration, resulting in a spark of molten steel when poured. Medical devices can cause side effects that can endanger the patient, without being seen clearly by the doctor responsible for the treatment. These problems are aggravated when the DST rules themselves change; software developers should test and possibly modify many programs, and users should install updates and restart the application. Consumers should update devices such as programmable thermostats with correct DST rules or manually adjust device hours. A common strategy for solving this problem in a computer system is to express the time using Coordinated Universal Time (UTC) rather than the local time zone. For example, Unix-based computer systems use UTC-based Unix time internally.
Some clock-shift problems can be avoided by adjusting the clock continuously or at least more gradually - for example, Willett initially suggests a 20 minute transition every week - but this will add complexity and has never been implemented.
DST inherits and can enlarge the standard time loss. For example, when reading a sun watch, one should balance it along with time zones and natural differences. Also, guidance on exposure to sunlight such as avoiding sunlight within two hours of daylight becomes less accurate when DST applies.
Terminology
As explained by Richard Meade in the English Journal of the National Council of Teachers of English, the form of daylight savings time (with "s") was already in 1978 much more common than the older < i> summer time in American English ("the changes are done"). Nevertheless, even dictionaries like Merriam-Webster, American Heritage, and Oxford, which describe actual usage rather than prescribe an outdated use (and therefore a newer list of forms), still list the older forms first. This is because the older form is still very common in print and favored by many editors. ("Though summer time is considered correct, summer time (with the letter" s ") is usually used.") The first two words are sometimes hyphenated (< i> daylight-saving (s) time ). Merriam-Webster also lists the form of daylight saving (no "time"), daylight savings (no "time"), and noon .
In England, Willett's proposal in 1907 uses the term daylight saving, but in 1911 the term summer time replaces daylight saving time in draft law. The same or similar expression is used in many other languages: Sommerzeit in German, zomertijd in Dutch, kesÃÆ'¤aika i> horario de verano or hora de verano in Spanish, and heure d'ÃÆ' © tà ©  © in French.
Local time names usually change when DST is observed. American English replaces default with daylight : for example, Pacific Standard Time ( PST ) to Daylight Pacific Time ( PDT ). In the UK, the standard term for English time when advanced by an hour is Summer Time (BST), and English English typically includes summer to other time zone names, such as Central European Time CET ) to Central European Summer Time ( CEST ).
Mnemonic English North American "spring forward, fall back" (also "spring forward...", "popping...", and "... falling behind") helps people remember which direction will shift the clock.
Computing
Changes to DST rules cause problems with existing computer installs. For example, a 2007 change to DST rules in North America requires that a lot of computer systems be upgraded, with the greatest impact on email programs and calendars. This increase requires significant effort by enterprise information technology.
Some applications are standardizing UTC to avoid issues with clock shifts and timezone differences. Likewise, most modern operating systems internally handle and store all the time as UTC and only convert to local time to display.
However, even if UTC is used internally, the system still requires a second leap update and timezone information to calculate the exact local time as needed. Many systems in use today base their date/time calculations from data derived from the tz database also known as zoneinfo .
IANA time zone database
The tz database maps names to locations called historical and clock predictions shifted. This database is used by many computer software systems, including most operating systems like Unix, Java, and Oracle RDBMS; HP "tztab" database is similar but not compatible. When the temporal authority changes the DST rules, zoneinfo updates are installed as part of regular system maintenance. In systems like Unix, the TZ environment variable specifies the location name, as in TZ = ': America/New_York' . In many of these systems there are also system-wide settings applied if the TZ environment variable is not set: this setting is controlled by the /etc/localtime file contents, which is usually a symbolic link or a hard link to one of the zoneinfo files. The internal time is stored in timezone independent time zone; TZ is used by each potentially large number of users and a simultaneous process to independently localize the time display.
Older or stripped systems may only support the PZ value required by POSIX, which determines at most one initial and final rule explicitly in the value. For example, TZ = 'EST5EDT, M3.2.0/02: 00, M11.1.0/02: 00' specifies the time for the eastern United States beginning 2007. Such TZ values ​​must be changed at any time Rules DST change, and new value is valid for all year, wrong handle long time stamp.
Microsoft Windows
As with zoneinfo, Microsoft Windows users configure DST by specifying location names, and the operating system then consults with the set of rules tables that need to be updated when the DST rules change. Procedures for defining names and updating tables vary with release. Update not issued for older versions of Microsoft Windows. Windows Vista supports at most two initial and final rules per time zone setting. At a Canadian site that observes DST, a Vista setting supports both post 1986-2007 and post-2006 stamps but incorrectly handles some of the older time stamps. Older Microsoft Windows systems typically store only one start and end rule for each zone, so the same reliable Canadian arrangement only supports post 2006 stamps.
This limitation has caused problems. For example, before 2005, DST in Israel varies every year and passes over several years. Windows 95 used the correct rules for 1995 alone, causing problems in the following years. In Windows 98, Microsoft marked Israel as having no DST, forcing Israeli users to manually shift their computer hours twice a year. The Israeli Daylight Savings 2005 law sets predictable rules using the Jewish calendar but Windows zone files can not represent the rule's date in an independent way. Partial workarounds, one handles long time stamps, including manually switch zone files every year and Microsoft tools that automatically switch zones. In 2013, Israel standardizes daylight saving time in accordance with the Gregorian calendar.
Microsoft Windows makes a real-time clock system in local time. This causes some problems, including compatibility when multi-booting with the operating system that clocks to UTC, and adjusts double-hours when multi-booting different versions of Windows, such as with rescue boot disks. This approach is a problem even in Windows systems only: there is no support for time zone settings per user, only a single system-wide setting. In 2008 Microsoft hinted that the upcoming Windows version will partially support the RealTimeIsUniversal Windows registry entries that have been introduced years before, when Windows NT supports RISC machines with UTC clocks, but is not maintained. Since then at least two fixes related to this feature have been published by Microsoft.
The NTFS file system used by the latest version of Windows stores files with UTC time stamps, but displays them corrected to local - or seasonal - time. However, the FAT filesystem commonly used on removable devices only stores local time. As a result, when a file is copied from the hard disk to a separate media, the time is set to the current local time. If the time setting is changed, the time stamp of the original file and the copy will be different. The same effect can be observed when compressing and opening file compression with some archivers files. This is an NTFS file that changes the visible time. This effect should be kept in mind when trying to determine whether a file is a duplicate of another, although there are other methods to compare files for equivalence (such as using checksum algorithms). The ready instructions are if the stamp time is different 1 hour.
Permanent summer time
A move for "permanent summer time" (fixed at summer time of the year without time shift) is sometimes recommended, and in fact is currently applied in some jurisdictions such as Belarus, parts of Russia (eg Novosibirsk), Turkey, Namibia, and SÃÆ' â € <â € <Â £ o TomÃÆ'Â © and PrÃÆ'ncipe. This could be the result of following the time zone of neighboring territory, political will or other causes. Advocates cite the same advantages as normal DSTs without problems associated with time shifts twice a year. However, many remain unsure of the benefits, citing the same problem and the relatively late sun, especially in winter, that the DST takes year-round.
Russia switched to a permanent DST from 2011 to 2014, but the move proved unpopular as the sun rose in the winter, so the country switched permanently back to "standard" or "winter" in 2014 for the whole of the Russian Federation. The United Kingdom and Ireland also experimented with summer time throughout the year between 1968 and 1971, and placed the clock ahead with additional hours during World War II.
In the IANA time zone database, the permanent summer time is considered the standard time that has been added one hour.
On March 23, 2018 Florida Governor Rick Scott signed a law requesting Congress to approve a noon time in Florida.
By country and region
- Summer time by country
- Africa
- Asia
- Europe
- North and South America
- Oceania
See also
- Winter time (pause)
References
Further reading
External links
- "Official Time 2015", Telecommunication Standardization Bureau of ITU
- Information on the Current Summer Rules (DST), U.S. National Institute of Standards and Technology
- Source for time zone and summer time data
Source of the article : Wikipedia
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