Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cloud Formation: How Feldspar Acts as Ice Nucleus

09.12.2016

In the atmosphere, feldspar particles act as ice nuclei that make ice crystals grow in clouds and enable precipitation. The reason was found by researchers of Karlsruhe Institute of Technology (KIT) and University College London (UCL) with the help of electron microscopy observations and molecular dynamics computer modeling. The ice nucleus proper is a quasi-hidden crystal surface of the feldspar that is exposed at surface defects only. The researchers present their findings that are of major relevance to the understanding of cloud and precipitation formation in Science. (DOI:10.1126/science.aai8034)

About 90 percent of precipitation over land depends on the formation of ice crystals in clouds, which fall down due to their increasing weight. But water in clouds only freezes when certain particles are present, on which ice crystals can grow. Of all aerosol particles, i.e. solid suspended particles in the atmosphere, however, only few act as ice nuclei.


Ice crystals on a feldspar crystallite under the electron microscope. Although they grow on various levels of the feldspar, they have the same orientation.

Photo: Alexei Kiselev and Dagmar Gerthsen, KIT

These rare aerosol particles decisively determine precipitation on earth. Hence, it is important to understand what makes them differ from other particles. “Such an understanding would improve our ability to predict ice and precipitation formation in a future changed climate with changed aerosol loading,” says Professor Thomas Leisner, Head of the Atmospheric Aerosol Research Division of KIT’s Institute of Meteorology and Climate Research (IMK-AAF).

Scientists of IMK-AAF, in cooperation with researchers of the KIT Laboratory of Electron Microscopy (LEM) and University College London (UCL) have now succeeded in solving this question for the most important class of inorganic atmospheric ice nuclei, i.e. mineral dust particles consisting of feldspar.

As is reported in the Science magazine, the scientists combined electron microscopy observations with molecular modeling to determine for the first time the atomic nature of this important inorganic ice nucleus.

They showed that ice starts to grow on feldspar crystallites not on the accessible crystalline faces, but at microscopic defects like edges, cracks, and small depressions. Even though these defects are distributed randomly at the crystallite surface, the ice crystals grow with the same orientation relative to the feldspar crystal lattice.

From these observations and from extensive molecular modeling, the scientists concluded that a specific crystal face that only occurs at defects on the surface of the feldspar crystallite is the underlying nucleus for ice formation.

“Feldspar is one of the most active atmospheric ice nucleating agents, but why it is so good at making ice has remained unclear,” said Professor Angelos Michaelides of UCL. “By identifying the active site for ice nucleation on feldspar, we have found an important piece of the puzzle.” The researchers now expect similar studies to reveal the properties of other minerals acting as ice nuclei.

Alexei Kiselev, Felix Bachmann, Philipp Pedevilla, Stephen J. Cox, Angelos Michaelides, Dagmar Gerthsen, and Thomas Leisner: Active sites in heterogeneous ice nucleation – the example of K-rich feldspars. Science, 2016. DOI: 10.1126/science.aai8034


More about the KIT Climate and Environment Center: http://www.klima-umwelt.kit.edu/english

Karlsruhe Institute of Technology (KIT) pools its three core tasks of research, higher education, and innovation in a mission. With about 9,300 employees and 25,000 students, KIT is one of the big institutions of research and higher education in natural sciences and engineering in Europe.

KIT – The Research University in the Helmholtz Association

For further information, please contact:

Margarete Lehné
Presse, Kommunikation und Marketing
Phone: +49 721 608-48121
Fax: +49 721 608-45681
margarete.lehne@kit edu

Monika Landgraf | Karlsruher Institut für Technologie
Further information:
http://www.kit.edu

More articles from Life Sciences:

nachricht Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University

nachricht Researchers discover specific tumor environment that triggers cells to metastasize
22.11.2017 | University of California - San Diego

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

UCLA engineers use deep learning to reconstruct holograms and improve optical microscopy

22.11.2017 | Medical Engineering

Watching atoms move in hybrid perovskite crystals reveals clues to improving solar cells

22.11.2017 | Materials Sciences

New study points the way to therapy for rare cancer that targets the young

22.11.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>