Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Constructal theory predicts global climate patterns in simple way

10.02.2006


A unifying physics principle that describes design in nature predicts, in surprisingly straightforward fashion, the basic features of global circulation and climate, according to researchers at Duke University’s Pratt School of Engineering and the University of Evora in Portugal. They said the new approach to climate may have important implications for forecasting environmental change.

The researchers found that the "constructal theory" can predict the global circulation that determines the boundaries between desert and tropical forests as well as between temperate zones and the poles. Based only on the optimal flow of heat from the sun, the theory also predicts other climate characteristics, such as average wind speed and the average temperature difference between night and day.

The findings may lead to a new understanding of the factors that drive global circulation patterns of the atmosphere and ocean, the researchers said. The theory might also prove useful for predicting the consequences of environmental change -- such as shifts in the atmospheric concentrations of greenhouse gases -- for broad weather patterns, they said.



The team, including Professor Adrian Bejan, of Duke’s Pratt School, who first developed constructal theory, reports its findings in a forthcoming issue of the International Journal of Heat and Mass Transfer (available online Jan. 19, 2006).

Constructal theory is founded on the principle that configurations evolve in time so as to optimize the flow of matter or energy. The theory has been applied previously in many arenas, including the internal structure of the lungs, river currents, and animal locomotion http://www.pratt.duke.edu/news/releases/index.php?story=243.

"We now demonstrate that the constructal theory of organization in nature predicts many characteristics of global circulation -- the grandest of all flow systems on Earth," said Bejan.

"While other very complicated empirical models predict the same basic features, constructal theory does this in a much simpler way," said geophysicist A. Heitor Reis of the University of Evora. "This is an entirely new kind of approach to climate."

Atmospheric circulation is the large-scale movement of air that distributes heat on the surface of the Earth, the researchers explained. These flows develop as air and water moves from hot to cold regions, a result of variation in the heating of the Earth’s surface by the sun.

Atmospheric circulation is characterized by three distinct bands, or convection cells, known as the equatorial Hadley cell, the Ferrel cell and the Polar cell, which drive wind and other air currents (link to illustration, http://en.wikipedia.org/wiki/Image:AtmosphCirc2.png).

Despite annual and daily variation in weather patterns, the basic climate conditions in a particular region remain fairly constant over periods on the order of 30 years, Reis said. It is the boundaries between the planet’s three-tiered global circulation that determines climate patterns and the location of biotic communities, such as deserts, forests and grasslands.

To apply the constructal theory to global climate, the researchers treated Earth as if it were a heat engine that, rather than doing work, dissipates all the power it produces through air and water currents.

"The Earth with its solar heat input, heat rejection, and wheels of atmospheric and oceanic circulation, is a heat engine without shaft," Bejan said. "Its maximized mechanical power cannot be delivered, but is instead destined to dissipate through air and water friction and other forms of heat loss. It produces maximum power, which it then dissipates at a maximum rate."

By applying this analogy, the researchers predicted the main characteristics of global circulation and climate based on very few inputs – namely the temperature of the sun, the solar constant, cloud cover and the Earth’s greenhouse factor. The solar constant refers to the amount of incoming solar radiation measured on the outer surface of Earth’s atmosphere. The greenhouse factor takes into account the concentrations of aerosols and greenhouse gases to determine the amount of heat energy trapped by the atmosphere.

"To my surprise, a simple theory anticipates the latitudinal boundaries of the three zones – the Hadley, Ferrel and Polar cells – which comprise the main global circulation on Earth," Reis said. The theory also predicted the average speed of atmospheric and oceanic flow and the average temperature on Earth, among other climate features, they reported.

A second version of the theory on the daily scale, which included the speed of Earth’s rotation, also predicted the average difference in temperatures between night and day.

The findings may change the understanding of the factors that drive climate patterns. For example, scientists have thought that the circulation zones arise due in part to the rotation of Earth, the researchers said.

"We cast doubt on this idea by showing that the circulation patterns can arise based solely on the optimal structure of global heat flow," Reis said.

The new climate theory may also aid in predicting the consequences of global change, the researchers said.

"If the properties of the atmosphere change as people say they will, we could anticipate what that might mean for global climate," Bejan said.

"By playing with the Earth’s greenhouse factor, we could determine what it would take to get another result," Reis added.

The findings, along with earlier applications of constructal theory, also add support for the theory’s general relevance to natural phenomena. "The accumulation of coincidences between theoretical predictions and natural facts adds weight to the claim that the constructal law is a law of nature," Bejan said.

Kendall Morgan | EurekAlert!
Further information:
http://www.duke.edu
http://www.pratt.duke.edu/news/releases/index.php?story=243
http://en.wikipedia.org/wiki/Image:AtmosphCirc2.png

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>