what is the difference between gregorian calendar and julian calendar
Julian calendar The Julian calendar has two types of year: "normal" years of 365 days and "leap" years of 366 days. There is a simple cycle of three "normal" years followed by a leap year and this pattern repeats forever without exception. The Julian year is, therefore, on average 365.25 days long. Consequently the Julian year drifts over time with respect to the tropical (solar) year. Although Greek astronomers had known, at least since Hipparchus, a century before the Julian reform, that the tropical year was slightly shorter than 365.25 days, the calendar did not compensate for this difference. As a result, the calendar year gains about three days every four centuries compared to observed equinox times and the seasons. This discrepancy was corrected by the Gregorian reform of 1582. The Gregorian calendar has the same months and month lengths as the Julian calendar, but, in the Gregorian calendar, year numbers evenly divisible by 100 are not leap years, except that those evenly divisible by 400 remain leap years.[3] This means since 16 February Julian (1 March 1900 Gregorian) and until 15 February Julian (28 February 2100 Gregorian) Julian is 13 days behind Gregorian and the disparity will widen.
July July is the seventh month of the year (between June and August) in the Julian and Gregorian Calendars and the fourth of seven months to have a length of 31 days. It was named by the Roman Senate in honour of Roman general Julius Caesar, it being the month of his birth. Prior to that, it was called Quintilis, being the fifth month of the 10-month calendar.
Season As noted, a variety of dates are used in different countries to mark the changes of seasons, especially those that are calendar based. These observances are often declared "official" within their respective jurisdictions by the local or national media, even when the weather or climate is contradictory.[20] However they are mainly a matter of custom only, and have not generally been proclaimed by governments north or south of the equator for civil purposes.[21][22] The Met Office in the UK uses a three-month definition, e.g. declaring "spring" to be March, April, and May.[23] At least one researcher writing in the Bulletin of the American Meteorological Society compared various definitions to actual temperature changes, and recommended this three-month definition for general use in the United States.[24]
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