Researchers studied the variations and fluctuations in the length of day over a one to 10 year period between 1962 and 2012
Research at the University of Liverpool has found that variations in the length of day over periods of between one and 10 years are caused by processes in the Earth’s core.
The Earth rotates once per day, but the length of this day varies. A year, 300million years ago, lasted about 450 days and a day would last about 21 hours.
Length of day increases
As a result of the slowing down of the Earth’s rotation the length of day has increased.
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.
The form of core motions giving rise to variations in Earth’s length of day
Professor Richard Holme, from the School of Environmental Sciences, studied the variations and fluctuations in the length of day over a one to 10 year period between 1962 and 2012. The study took account of the effects on the Earth’s rotation of atmospheric and oceanic processes to produce a model of the variations in the length of day on time scales longer than a year.
Professor Holme said: “The model shows well-known variations on decadal time scales, but importantly resolves changes over periods between one and 10 years.
“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.”
The research was conducted in partnership with the Université Paris Diderot and is published in Nature.
You must be logged in to post a comment.
All recent news
Mosquito-borne viruses linked to stroke
Match-fixing Red Button app to go global following study
20: Ethics of Care
We’ve known for over a century that our environment shapes our health, so why are we still blaming unhealthy lifestyles?
University technician shortlisted in Times Higher Education Awards
Front page of our News site this morning 🗞️
The connection between mosquito-borne viruses and #stroke, match-fixing Red Button app to go global and Liverpool Literary Festival returns October 9-11
Find it all here 👉 https://news.liverpool.ac.uk/
1/ Today, we are launching COVID-19 Policy Brief 024 with @LpoolCityRegion, a paper by Dan Exeter, Janine Paynter & Chris Bullen @AucklandUni: ‘Going Hard & Going Early in NZ: The “Team of 5 Million” Unites Against C-19’ https://bit.ly/3b5cb8L
My briefing paper on the UK Internal Market Bill and its implications for devolution in Scotland and Wales, is now available to download from here: