Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Insoluble Dust Plays Important Role in Cloud Formation

17.10.2011
New information on the role of insoluble dust particles in forming cloud droplets could improve the accuracy of regional climate models, especially in areas of the world that have significant amounts of mineral aerosols in the atmosphere. A more accurate accounting for the role of these particles could also have implications for global climate models.

Cloud properties can have a significant impact on climate, yet the effects of aerosols like dust is one of the more uncertain components of climate change models. Scientists have long recognized the importance of soluble particles, such as sea salt and sulfates, in creating the droplets that form clouds and lead to precipitation. But until now, the role of insoluble particles – mostly dust swept into the atmosphere from such sources as deserts – hasn’t figured significantly in climate models.

Using a combination of physics-based theory and laboratory measurement of droplet formation, researchers at the Georgia Institute of Technology have developed a model that can be added to existing regional and global climate simulations. The impacts of these refinements on cloud condensation nuclei (CCN) activity and droplet activation kinetics are still being studied.

“Understanding that insoluble dust forms more droplets than we thought it could, and that those droplets form close to the sources of the particles, could change our picture of how precipitation is formed in areas like the Mediterranean, Asia and other climate-stressed regions,” said Athanasios Nenes, a professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology.

The research was supported by the National Science Foundation (NSF), the National Oceanic and Atmospheric Administration (NOAA) and NASA. The findings were described at the Fall 2011 meeting of the American Chemical Society in Denver, and reported in the journals Geophysical Research Letters, Journal of Geophysical Research and Atmospheric Chemistry and Physics. A new paper on the global modeling impacts has been accepted for publication by the Journal of Geophysical Research.

Soluble particles nucleate droplets by absorbing water under conditions of high humidity. Insoluble materials such as dust cannot absorb water, so it was thought that they played little role in the formation of clouds and precipitation.

However, Nenes and collaborators realized that these dust particles could nucleate droplets in a different way – by adsorbing moisture onto their surfaces, much as moisture condenses on window glass during temperature changes. Some insoluble particles containing clay materials may also adsorb moisture, even though they don’t dissolve in it.

Working with Irina Sokolik, also a professor in the School of Earth and Atmospheric Sciences, Nenes and graduate student Prashant Kumar studied aerosol particles created from samples of desert soils from several areas of the world, including Northern Africa, East Asia/China and North America. In laboratory conditions simulating those of a saturated atmosphere, these insoluble particles formed cloud droplets, though the process was slower than the one producing droplets from soluble materials.

“We generated particles in the laboratory from materials we find in the atmosphere,” explained Nenes, who also holds a faculty appointment in Georgia Tech’s School of Chemical and Biomolecular Engineering. “These particles take up water using a mechanism that had not been considered before in models. It turns out that this process of adsorption soaks up enough water to form cloud droplets.”

The laboratory work showed that smaller particles were more likely than expected to generate droplets, and that their effectiveness as cloud condensation nuclei was affected by the type of minerals present, their size, morphology and processes affecting them in the atmosphere. The dust particles ranged in size from 100 nanometers up to a few microns.

These mineral aerosols may consist of iron oxides, carbonates, quartz and clays. They mainly originate from arid and semi-arid regions, and can remain suspended in the atmosphere for as long as several weeks, allowing them to be transported long distances from their original sources. In the atmosphere, the dust particles tend to accumulate soluble materials as they age.

“We can simulate what is happening to the particles as they get slowly coated with more and more soluble materials,” said Nenes. “As they get more and more soluble coatings on them, they become more hygroscopic.”

The researchers are now working with collaborators in Germany to incorporate their new theories into existing climate models to see how they may change the predictions. They also hope to carry out new field work to measure the activity of these insoluble aerosols in real-world conditions.

“We now need to study the cloud particles in the atmosphere and their ability to form droplets to verify our theory using real atmospheric data,” Nenes said. “We also need to look at dust and clouds from more regions of the world to make sure that the theory works for all of them.”

Clouds play an important role in governing climate, so adding new information about their formation could improve the accuracy of complex climate models.

“The reason that we care about particle-cloud interactions is that they introduce a lot of uncertainties in climate model predictions,” Nenes said. “Anything that can be done to improve these predictions by providing more specific cloud information would be helpful to projecting climate change.”

Research News & Publications Office
Georgia Institute of Technology
75 Fifth Street, N.W., Suite 314
Atlanta, Georgia 30308 USA
Media Relations Contacts: John Toon (404-894-6986)(jtoon@gatech.edu) or Abby Robinson (404-385-3364)(abby@innovate.gatech.edu).

Technical Contact: Athanasios Nenes (athanasios.nenes@gatech.edu).

Writer: John Toon

John Toon | Newswise Science News
Further information:
http://www.gatech.edu

More articles from Earth Sciences:

nachricht Atmospheric scientists reveal the effect of sea-ice loss on Arctic warming
11.03.2019 | Institute of Atmospheric Physics, Chinese Academy of Sciences

nachricht Sensing shakes
11.03.2019 | University of Tokyo

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

Im Focus: Revealing the secret of the vacuum for the first time

New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum

For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...

Im Focus: Sussex scientists one step closer to a clock that could replace GPS and Galileo

Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Molecular motors run in unison in a metal-organic framework

20.03.2019 | Life Sciences

Active substance from plant slows down aggressive eye cancer

20.03.2019 | Life Sciences

Novel sensor system improves reliability of high-temperature humidity measurements

20.03.2019 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>