Posts Tagged ‘Manchester University’

“Climate science” now hunting for cooling effects – and finds the brightness of clouds

May 6, 2013

How is it that – for a settled science – all these new “cooling” mechanisms are suddenly being found? Could it have something to do with trying to rescue climate models which have failed to predict the slowdown in global warming? “Climate science” is now hunting for previously unidentified cooling effects to explain the warming that has not happened.

This time it is the brightness of clouds! Apparently manmade pollution in the form of organics can enhance the formation of clouds which happen to be brighter from above and which reflect more of the suns radiation. Voilà! An as yet unidentified cooling effect.

But this conclusion comes not from measurements but from yet another model!

From the University of Machester (via Alpha Galileo):

Organic vapours affect clouds leading to previously unidentified climate cooling

University of Manchester scientists, writing in the journal Nature Geoscience, have shown that natural emissions and manmade pollutants can both have an unexpected cooling effect on the world’s climate by making clouds brighter.

Clouds are made of water droplets, condensed on to tiny particles suspended in the air. When the air is humid enough, the particles swell into cloud droplets. It has been known for some decades that the number of these particles and their size control how bright the clouds appear from the top, controlling the efficiency with which clouds scatter sunlight back into space. A major challenge for climate science is to understand and quantify these effects which have a major impact in polluted regions.

The tiny seed particles can either be natural (for example, sea spray or dust) or manmade pollutants (from vehicle exhausts or industrial activity). These particles often contain a large amount of organic material and these compounds are quite volatile, so in warm conditions exist as a vapour (in much the same way as a perfume is liquid but gives off an aroma when it evaporates on warm skin).

The researchers found that the effect acts in reverse in the atmosphere as volatile organic compounds from pollution or from the biosphere evaporate and give off characteristic aromas, such as the pine smells from forest, but under moist cooler conditions where clouds form, the molecules prefer to be liquid and make larger particles that are more effective seeds for cloud droplets.

“We discovered that organic compounds such as those formed from forest emissions or from vehicle exhaust, affect the number of droplets in a cloud and hence its brightness, so affecting climate,” said study author Professor Gordon McFiggans, from the University of Manchester’s School of Earth, Atmospheric and Environmental Sciences.

“We developed a model and made predictions of a substantially enhanced number of cloud droplets from an atmospherically reasonable amount of organic gases.

“More cloud droplets lead to brighter cloud when viewed from above, reflecting more incoming sunlight. We did some calculations of the effects on climate and found that the cooling effect on global climate of the increase in cloud seed effectiveness is at least as great as the previously found entire uncertainty in the effect of pollution on clouds.”

  • ‘Cloud droplet number enhanced by co-condensation of organic papers,’ by Gordon McFiggans et al, will be published in Nature Geoscience on Sunday 5 May 2013.

Physics Nobel for graphene

October 5, 2010

What I thought might be the subject area of the Chemistry Nobel was in fact rewarded with the Physics Nobel prize today.

The Nobel Prize in Physics 2010 was awarded jointly to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene”

BBC: Andrei Geim and Konstantin Novoselov, both at Manchester University, UK, took the prize for research on graphene. Geim, 51, is a Dutch national while Novoselov, 36, holds British and Russian citizenship. Both are natives of Russia and started their careers in physics there.

Andre Geim

Andre Geim: Wikipedia

Graphene is a flat sheet of carbon just one atom thick; it is almost completely transparent, but also extremely strong and a good conductor of electricity. It consists of a hexagonal array of sp2-bonded carbon atoms, just like those found in bulk graphite. 2D materials display very interesting properties, and are fundamentally different from the 3D materials we encounter everyday. The discovery of 2D materials means that scientists now have access to materials of all dimensionalities, including 0D (quantum dots, atoms) and 1D (nanowires, carbon nanotubes).

Geim and Novoselov first isolated the fine sheets of graphene from graphite. A layer of graphite one millimetre thick actually consists of three million layers of graphene stacked on top of one another. The layers are weakly held together and are therefore fairly simple to tear off and separate. The researchers used ordinary sticky tape to rip off thin flakes from a piece of graphite. Then they attached the flakes to a silicon plate and used a microscope to identify the thin layers of graphene among larger fragments of graphite and carbon scraps.

Graphene can be used for many different purposes including transistors, gas sensors, support membranes for TEM and inert transparent coatings.

Konstantin Novoselov

Konstantin Novoselov : Photo: University of Manchester, UK

It provides the possibility for further research in quantum physics, relativity and has allowed the Klein paradox to be observed for the first time.

Some scientists have precicted that graphene could one day replace silicon – which is the current material of choice for transistors. It could also yield incredibly strong, flexible and stable materials and find uses in transparent touch screens or solar cells.

Ten years ago, Professor Geim and Professor Sir Michael Berry from the University of Bristol were jointly awarded an Ig Nobel prize for their experiments using magnetic fields to levitate live frogs.

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