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 Supercomputing helps researchers understand Earth's interior
23.05.2017 | University of Illinois College of Liberal Arts & Sciences

nachricht How is climate change affecting fauna in the Arctic?
22.05.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

 
Latest News

Scientists propose synestia, a new type of planetary object

23.05.2017 | Physics and Astronomy

Zap! Graphene is bad news for bacteria

23.05.2017 | Life Sciences

Medical gamma-ray camera is now palm-sized

23.05.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>