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Weather Glossary - Y



The interval required for the earth to complete one revolution around the sun. A sidereal year, which is the time it takes for the earth to make one absolute revolution around the sun, is 365 days, 6 hours, 9 minutes and 9.5 seconds. The calendar year begins at 12 o'clock midnight local time on the night of December 31st-January 1st. Currently, the Gregorian calendar of 365 days is used, with 366 days every four years, a leap year. The tropical year, also called the mean solar year, is dependent on the seasons. It is the interval between two consecutive returns of the sun to the vernal equinox. In 1900, that took 365 days, 5 hours, 48 minutes, and 46 seconds, and it is decreasing at the rate of 0.53 second per century. This decrease is due to the slow precession of the Earth's axis of rotation.

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Global warming and El Nino set to make 2015 the hottest year on record, WMO says

22:50 EDT

This year is set to be the hottest on record, due to a strong El Nino season and global warming, the World Meteorological Organisation (WMO) says.

'Weather nerd' and social media celebrity joins Victoria's list of unsung Bureau of Meteorology heroes

20:32 EDT

Jono Ingram might refer to himself as a 'weather nerd', but to Donald locals in western Victoria, he is an online celebrity.

Tassie's taste of winter weather

20:16 EDT

A strong front is bringing damaging winds, with rain and snow to follow.