Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Changes In The Earth’s Rotation Are In The Wind

06.03.2003


Because of Earth’s dynamic climate, winds and atmospheric pressure systems experience constant change. These fluctuations may affect how our planet rotates on its axis, according to NASA-funded research that used wind and satellite data.




NASA’s Earth Science Enterprise (ESE) mission is to understand the Earth system and its response to natural and human-induced changes for better prediction of climate, weather and natural hazards, such as atmospheric changes or El Nino events that may have contributed to the affect on Earth’s rotation.

"Changes in the atmosphere, specifically atmospheric pressure around the world, and the motions of the winds that may be related to such climate signals as El Nino are strong enough that their effect is observed in the Earth’s rotation signal," said David A. Salstein, an atmospheric scientist from Atmospheric and Environmental Research, Inc., of Lexington, Mass. who led a recent study.


From year to year, winds and air pressure patterns change, causing different forces to act on the solid Earth. During El Nino years, for example, the rotation of the Earth may slow ever so slightly because of stronger winds, increasing the length of a day by a fraction of a millisecond (thousandth of a second).

Issac Newton’s laws of motion explain how those quantities are related to the Earth’s rotation rate (leading to a change in the length of day) as well as the exact position in which the North Pole points in the heavens (known also as polar motion, or Earth wobble).

To understand the concept of angular momentum, visualize the Earth spinning in space. Given Earth’s overall mass and its rotation, it contains a certain amount of angular momentum. When an additional force acting at a distance from the Earth’s rotational axis occurs, referred to as a torque, such as changes in surface winds, or the distribution of high and low pressure patterns, especially near mountains, it can act to change the rate of the Earth’s rotation or even the direction of the rotational axis.

Because of the law of "conservation of angular momentum," small but detectable changes in the Earth’s rotation and those in the rotation of the atmosphere are linked. The conservation of angular momentum is a law of physics that states the total angular momentum of a rotating object with no outside force remains constant regardless of changes within the system.

An example of this principle occurs when a skater pulls his or her arms inward during a spin (changing the mass distribution to one nearer the rotation axis, reducing the "moment of inertia," and speeds up (increasing the skater’s spin); because the moment of inertia goes down, the spin rate must increase to keep the total angular momentum of the system unchanged.

"The key is that the sum of the angular momentum (push) of the solid Earth plus atmosphere system must stay constant unless an outside force (torque) is applied," Salstein said. "So if the atmosphere speeds up (stronger westerly winds) then the solid Earth must slow down (length-of-day increases). Also if more atmosphere moves to a lower latitude (further from the axis of rotation), and atmospheric pressure increases, it also gains angular momentum and the Earth would slow down as well."

Other motions of the atmosphere such as larger mass in one hemisphere than the other can lead to a wobble (like a washing machine with clothes off-balance) and the poles move, in accordance to the law of the conservation of angular momentum.

Salstein looked at wind and pressure measurements from a National Weather Service analysis that makes use of a combination of ground-based, aircraft, and space-based observations. The measurements for the Earth’s motions come from a variety of space-based measurements including satellites, like those in the Global Positioning System (GPS), the geodetic satellites that included records from NASA’s older LAGEOS satellite, and observations of distant astronomical objects using a technique known as Very Long Baseline Interferometry. Understanding the atmospheric pressure patterns, moreover, is essential to interpret results from NASA’s Gravity Recovery and Climate Experiment (GRACE).

The fact that the two vastly different systems, namely the meteorological and the astronomical, are in good agreement according to the conservation of angular momentum gives us assurance that both these types of measurements must be accurate. It shows, moreover, that changes in climate signals can have global implications on Earth’s overall rotation.

NASA’s ESE research focuses on the changes and variability in the Earth system, including atmospheric, oceanic, and geodetic areas. This research was recently presented at the annual meeting of the American Meteorological Society in Long Beach, Calif.

Rob Gutro | NASA Goddard Space Flight Center
Further information:
http://www.gsfc.nasa.gov/topstory/2003/0210rotation.html

More articles from Earth Sciences:

nachricht Wintertime Arctic sea ice growth slows long-term decline: NASA
07.12.2018 | NASA/Goddard Space Flight Center

nachricht Why Tehran Is Sinking Dangerously
06.12.2018 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

New discoveries predict ability to forecast dementia from single molecule

12.12.2018 | Health and Medicine

CCNY-Yale researchers make shape shifting cell breakthrough

12.12.2018 | Physics and Astronomy

Pain: Perception and motor impulses arise in the brain independently of one another

12.12.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>