Weather Glossary - Y

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Year

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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Heatwave update: Temperatures are expected to peak over the coming days

01:21 EDT

Tennis players are sweating, toxic ozone warnings are out for Sydney and fruit is cooking on the branches.

Fifty bushwalkers airlifted to safety in Tasmania's south as fires burn across state

19:22 EDT

Fifty bushwalkers have been airlifted to safety in Tasmania's Southwest National Park after lightning strikes sparked a series of fires across the state.

BOM forecasts 47C in outback NSW as heatwave sparks ozone gas warning in Sydney's west

15:28 EDT

Records have tumbled for the hottest January day in several NSW towns as the state endures day two of a severe heatwave.