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 Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>