"අධික අවුරුද්ද" හි සංශෝධන අතර වෙනස්කම්

A '''leap year''' (or '''intercalary year''') is a year containing one or more extra days (or, in the case of [[lunisolar calendar]]s, an extra month) in order to keep the [[calendar year]] synchronised with the [[astronomical year|astronomical]] or [[seasonal year]]. For example, in the [[Gregorian calendar]], February in a leap year has 29 days instead of the usual 28 so the year lasts 366 days instead of the usual 365. Because seasons and astronomical events do not repeat in a [[whole number]] of days, a calendar that had the same number of days in each year would, over time, drift with respect to the event it was supposed to track. By occasionally inserting (or ''[[intercalation|intercalating]]'') an additional day or month into the year, the drift can be corrected. A year that is ''not'' a leap year is called a ''[[common year]]''.

 

In the [[Gregorian calendar]], the current standard calendar in most of the world, most years whose division by 4 equals an [[integer]] are leap years. In each leap year, the month of February has 29 days instead of 28. Adding an extra day to the calendar every four years compensates for the fact that a period of 365 days is shorter than a [[solar year]] by almost 6 hours.

 

This rule gives an average year length of 365.242222… days. This is a very good approximation to the ''mean'' [[tropical year]], but because the ''vernal equinox'' year is slightly longer, the Revised Julian calendar does not do as good a job as the Gregorian calendar of keeping the vernal equinox on or close to March 21.

 

The [[Chinese calendar|Chinese]] and [[Korean calendar]]s are [[lunisolar calendar|lunisolar]], so a leap year has an extra ''month'', often called an ''embolismic'' month after the Greek word for it. In the Chinese calendar the [[leap month]] is added according to a complicated rule, which ensures that month 11 is always the month that contains the northern winter [[solstice]]. The intercalary month takes the same number as the preceding month; for example, if it follows the second month (二月) then it is simply called "leap second month" ({{zh-tsp|t=閏二月|s=闰二月|p=rùn'èryuè}}).

 

The [[Hebrew calendar]] is also lunisolar with an embolismic month. This extra month is called ''Adar Alef'' ([[Adar 1|first Adar]]) and is added before ''[[Adar]]'', which then becomes ''Adar Bet'' ([[Adar 2|second Adar]]). According to the [[Metonic cycle]], this is done seven times every nineteen years (specifically, in years 3, 6, 8, 11, 14, 17, and 19).

 

Years consisting of 12 months have between 353 and 355 days. In a ''k'sidra'' ("in order") 354-day year, months have alternating 30 and 29 day lengths. In a ''chaser'' ("lacking") year, the month of [[Kislev]] is reduced to 29 days. In a ''malei'' ("filled") year, the month of [[Cheshvan]] is increased to 30 days. 13-month years follow the same pattern, with the addition of the 30-day Adar Alef, giving them between 383 and 385 days.

 

In the [[Islamic calendar]], leap months are not used. The [[Qur'an]] says:

 

The [[Thai solar calendar]] uses the [[Buddhist Era]] (BE), but has been synchronized with the Gregorian since [[AD]] 1941.

 

In the [[Hindu calendar]], which is a [[lunisolar calendar]], the embolismic month is called ''adhika maasa'' (extra month). It is the month in which the sun is in the same sign of the stellar zodiac on two consecutive dark moons. ''Adhika maasa'' occurs once every two or three years, compensating for the approximately eleven fewer days per year in twelve lunar months than the solar calendar. Thus, Hindu festivals tend to occur within a given span of the Gregorian calendar. For example: the No Moon during Diwali festival tends to occur between October 22 and November 15. [[Buddhist calendar]]s in several related forms (each a simplified version of the Hindu calendar) are used on mainland Southeast Asia in the countries of Cambodia, Laos, [[Thai lunar calendar|Thailand]], Myanmar (formerly Burma) and Sri Lanka.