The FINANCIAL — Variations in the length of day over periods of between one and 10 years are caused by processes in the Earth’s core, found a research at the University of Liverpool.
The Earth rotates once per day, but the length of this day varies. A year, 300 million years ago, lasted about 450 days and a day would last about 21 hours.
The rotation of the earth on its axis, however, is affected by a number of other factors – for example, the force of the wind against mountain ranges changes the length of the day by plus or minus a millisecond over a period of a year, according to the London School of Economics and Political Science.
“The model shows well-known variations on decadal time scales, but importantly resolves changes over periods between one and 10 years," said Professor Richard Holme, from the School of Environmental Sciences, who studied the variations and fluctuations in the length of day over a one to 10 year period between 1962 and 2012.
“Previously these changes were poorly characterised; the study shows they can be explained by just two key signals, a steady 5.9 year oscillation and episodic jumps which occur at the same time as abrupt changes in the Earth’s magnetic field, generated in the Earth’s core," he added.
“This study changes fundamentally our understanding of short-period dynamics of the Earth’s fluid core. It leads us to conclude that the Earth’s lower mantle, which sits above the Earth’s outer core, is a poor conductor of electricity giving us new insight into the chemistry and mineralogy of the Earth’s deep interior,” Proffessor said.
The research was conducted in partnership with the Université Paris Diderot and is published in Nature.
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