Bangalore scientists on cloud nine

www.mangaloretoday.com

New Delhi, Oct 18, 2011: Bangalore-based scientists have recreated naturally flowing clouds seen during rainy season in laboratory, opening up new avenues for weather scientists to study climate and monsoon behaviour with better precision.

“We are the first to simulate physically in  laboratory what appears to be a very realistic cloud flow. Such simulations have been attempted for more than 50 years, but with no success,” Roddam Narsimha from Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), who led a team of five researchers, told Deccan Herald. Clouds remain the weak link in modelling tropical rainfall pattern. In 2007, a report of the UN International Panel on Climate Change identified clouds as the largest source of uncertainty in climate change predictions.

 

 

For years, scientists have tried to generate artificial clouds that will mimic mother nature. But there was no breakthrough. Now,  the JNCASR team, which published the achievement in September 27 issue of “Proceedings of National Academy of Sciences,” seems to moved forward.

The World Meteorological Organisation classifies clouds into a few hundred types. Of these, there is one type called cumulus, which is most beautiful, most dynamic and scientifically relevant for India.

The cumulus clouds are recognised by their appearance—heaps or piles with sharp edges and cauliflower like domes. Sometimes they rise to great heights as slim, tall towers.

These clouds are dynamic not only because they change shape and grow and die, but also because air is flowing into, within and out of the clouds, which are crucial in determining the influence of clouds on monsoons and climate change.

“Under certain conditions, dry air is sucked into cloud and become moist. How it happens remain an enduring puzzle for 50 years. Understanding this has huge implications for weather and climate modeling,” said Narsimha.

The JNCASR team used a large water tank and regulated temperature, pressure, air flow and acidity of water to create the natural cloud flow. One of the team’s achievements was separation of two components of cloud formation—heating and fluid dynamics—in the laboratory. The researchers created half-a-dozen most important types of cumulus cloud and claimed other types of cloud could also be created.

“This paper is an extremely important step in understanding of clouds. The ground-breaking research results from amazing laboratory experiments,” said Robert Houze of the University of Washington, an authority on cloud dynamics.

Narsimha explained that the key determinant behind cloud evolution and sucking of dry air is the heat released on condensation or freezing of water vapour. But this variable does not appear in present cloud models at all.

“Other cloud-making efforts in the laboratory failed because clouds made in the laboratory would have to be small and the laws that govern how the real flow can be simulated on a smaller scale had not been discovered,” he explained.

Courtesy: Deccan Herald