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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Cyclone Trevor strengthens to category three as it nears Far North Queensland coast

08:22 EDT

Severe Tropical Cyclone Trevor is now a category three system and could intensify further before it makes landfall tonight, the Bureau of Meteorology has said.

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08:14 EDT

This briefing is compiled by the ABC's digital journalists in Sydney.

Tropical Cyclone Trevor forms off Far North Queensland coast as storms hit the south east

01:03 EDT

Tropical Cyclone Trevor is expected to intensify to a category three system before it crosses Queensland's Cape York Peninsula on Tuesday night.