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.
Victoria and Tasmania won't have time to recover from damaging winds this morning, with rain threatening to cause flooding across both states in the next 24 hours.
Hundreds of Victorians have been left without power as strong winds batter the state, with gusts of more than 100 kilometres per hour recorded at Melbourne airport.
Smoke blanketing Sydney this morning gave a face to a typically invisible phenomenon in our atmosphere, known as a temperature inversion.