Fairfax Media Network

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.

Display Your Local Weather

Weather News

Aurora Australis puts on a show

11:14 EDT

The last few nights have brought a spectacular light show to Tasmania, southern Victoria and New Zealand, with the potential for more to come over the next few weeks.

Grantham floods inquiry: Denis Wagner considers legal options after report finds quarry impact 'insignificant'

07:47 EDT

The former owner of the Grantham quarry is considering his legal options after an inquiry found it did not contribute to the town's deadly 2011 floods.

Grantham floods inquiry: Quarry played 'insignificant' role in disaster, commission rules

19:22 EDT

The Grantham Floods Commission of Inquiry has ruled the Grantham quarry played little role in the deadly 2011 flood and its owners were unjustly blamed.