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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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Cyclone Nora hits the Queensland coast as a category three system

01:30 EDT

Tropical Cyclone Nora has struck the far north Queensland coast as a category three system.

Gusty storms bring gloomy weekend to Victoria

15:53 EDT

A series of low pressure troughs have brought thundery showers to western and central Victoria on Saturday, with most of the rain associated with these systems falling over southern parts.

Tropical Cyclone Nora expected to reach category four before hitting Queensland

15:50 EDT

Rapidly intensifying Tropical Cyclone Nora is expected to become a category four system in Queensland's Gulf of Carpentaria later today, the Bureau of Meteorology (BOM) has warned.