Satellite Banner
Scientific Communities
Become a Member | Sign in
Home>News>This Article

Pollution Doesn’t Change the Rate of Cloud Droplet Formation, Study Shows

Published: Wednesday, February 20, 2013
Last Updated: Wednesday, February 20, 2013
Bookmark and Share
When it comes to forming the droplets that make up clouds, a little oily and viscous organic material apparently doesn’t matter that much.

Understanding cloud formation is essential for accurate climate modeling, and understanding cloud formation begins with the droplets that make up clouds. Droplets form when water vapor is attracted to particles floating in the atmosphere. These particles include dust, sea salt from the ocean, microorganisms, soot, sulfur – and organic material that can be both viscous and oily.

For years, scientists had believed that particles coated with this organic “goop” – produced by combusted petroleum and biomass – could form droplets more slowly than other particles. That would have had a significant impact on the formation of clouds.

But a study being reported this week in the journal Proceedings of the National Academy of Sciences suggests that the long-held belief isn’t true. Based on aerial and ground-based measurements of droplet formation from ten different areas of the northern hemisphere, researchers at the Georgia Institute of Technology report that organic coatings on particles don’t seem to significantly affect the rate at which droplets form. The researchers studied a wide range of particles, including organic, hydrocarbon-rich particles from the 2010 Deepwater Horizon oil spill in the Gulf of Mexico.

“It turns out that it doesn’t matter how much goop you have – or don’t have – the droplets take the same time to form,” said Athanasios Nenes, a professor in the School of Earth and Atmospheric Sciences and the School of Chemical and Biomolecular Engineering at Georgia Tech. “Even in extreme environments like Deepwater Horizon, the rate of droplet formation on particles found over the spill doesn’t differ from that of typical sea salt particles.”

The research was scheduled to be published in the early online edition of the journal during the week of February 18th. The research was supported by the National Science Foundation (NSF), NASA, the Department of Energy (DOE), the National Oceanic and Atmospheric Administration (NOAA) and the Office of Naval Research (ONR).

Clouds can hold in heat emitted from the Earth’s surface, contributing to climate warming. But they can also reflect incoming sunlight back to space, producing a climate cooling effect. Predicting how cloud cover will change in the future is therefore essential to good climate modeling.

“The reason we care about droplet formation rates is because the more slowly the droplets form, the more droplets you end up having in clouds,” Nenes said. “This, in turn, affects cloud properties and their climate impacts. For many years, there was the perception that having a lot of oily organic compounds from pollution would make water uptake a lot slower and might make droplets take longer to form. If that were true, it would mean that the impact pollution could have on clouds and climate would be much larger than we thought.”

And that created a large question mark in climate models.

To address that issue, Nenes and his collaborators began a series of studies using a mini cloud formation chamber small enough to be operated aboard an aircraft. The chamber consists of a long metal tube that is heated at one end and cooled at the other. The walls of the chamber are kept moist, and air containing particles from outside the aircraft is flowed through. Droplets form on the particles when air in the chamber becomes cool enough that it can no longer retain the moisture. The droplets then exit the chamber where they can be studied.

“With the chamber, we essentially create a cloud in a tube,” Nenes said. “The difference between the cloud in the tube and the cloud outside is that the tube allows us to precisely control the temperature and the amount of water vapor available. We know exactly what is going on with that cloud, and this allows for very accurate measurements of cloud formation.”

Beginning in 2004, Nenes and his graduate students took the chamber along on ten missions operated by NASA, NSF, NOAA and ONR. They flew through the pristine air of the Arctic, smoke from forest fires in Canada, and polluted air masses over the United States. They also sampled polluted air over Mexico City, clean air over the forests of Finland, and dust-laden air over the Mediterranean. Though the particles flowing through the cloud chamber were different each time, the rate at which they formed droplets, the condensation coefficient, remained the same.

“We have literally hundreds of hours of data studying cloud formation from areas all over the globe,” Nenes said. “We didn’t see any changes in the droplet nucleation time scale.”

In future studies, Nenes would like to study particles from other areas of the world, especially Africa and China. He’d also like to see what happens when the temperature of the air flowing through the cloud chamber is cold enough to form ice. There is some evidence that the kinetics of ice formation may be different in particles that are rich in “goop.”

The study of droplet formation provides one small step toward reducing the uncertainty in climate modeling.

“This is good for atmospheric and climate scientists, because some of the uncertainty of droplet formation and aerosol impacts goes away,” Nenes added. “With careful measurements and global deployment of measuring instruments, you can actually resolve outstanding questions in cloud physics and help simplify the descriptions of clouds in climate models.”

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More Than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Metabolic Profiles Distinguish Early Stage Ovarian Cancer with Unprecedented Accuracy
Studying blood serum compounds of different molecular weights has led scientists to a set of biomarkers that may enable development of a highly accurate screening test for early-stage ovarian cancer.
Thursday, November 19, 2015
Informatics Tool Helps Scientists Prioritize Protein Modification Research
Researchers have developed a new informatics technology that analyzes existing data repositories of protein modifications and 3D protein structures to help scientists identify and target research on "hotspots" most likely to be important for biological function.
Tuesday, June 30, 2015
Non-Aqueous Solvent Supports DNA Nanotech
Researchers at the Georgia Institute of Technology have now shown that they can assemble DNA nano-structures in a solvent containing no water.
Thursday, May 28, 2015
How Hep C Survives Immune System Attacks
Using mathematical modelling researchers have uncovered the tactics employed by the Hep C in order to avoid the immune system.
Thursday, May 28, 2015
Honey Bees Use Multiple Genetic Pathways To Fight Infections
The findings may help scientists develop honey bee treatments that are tailored to specific types of infections.
Monday, March 30, 2015
How Breast Cancer Cells Break Free To Spread In The Body
Analysis of the downstream signaling pathways of a gene called SNAIL could be used to identify potential targets for scientists who are looking for ways to block or slow metastasis.
Thursday, December 18, 2014
Microparticles Create Localized Control of Stem Cell Differentiation; Reduce Growth Factor Use
Scientists report advances in the growth of 3D cellular structures.
Friday, July 12, 2013
Study Shows that Delivering Stem Cells Improves Repair of Major Bone Injuries in Rats
The study reinforces the potential value of stem cells in repairing major injuries involving the loss of bone structure.
Thursday, January 21, 2010
Cancer Biomarker Identification Software Tools Earn Certification
caCORRECT and omniBioMarker are being made available to cancer researchers to remove artifacts and identify and validate biomarkers from microarray data.
Monday, August 24, 2009
Optical Breakthrough Makes “Lab-on-a-Chip” Possible
Compact device can pack big sensing power on a chip.
Thursday, August 03, 2006
Georgia Tech Invention Captures Cell Properties and Biochemical Signals in Action
Georgia Tech researchers have created the Scanning Mass Spectrometry probe, that can capture both the biochemical makeup and topography of complex biological objects in their normal environment.
Monday, July 31, 2006
Georgia Tech Creates Self-Training Gene Prediction Program
The software program may help researchers save a year or more in a genome sequencing and interpretation project.
Monday, June 19, 2006
New Device Revolutionizes Nano Imaging
Georgia Tech researchers have created a highly sensitive atomic force microscopy technology capable of high-speed imaging 100 times faster than current AFM.
Friday, April 21, 2006
Scientific News
High Throughput Mass Spectrometry-Based Screening Assay Trends
Dr John Comley provides an insight into HT MS-based screening with a focus on future user requirements and preferences.
How a Genetic Locus Protects Adult Blood-Forming Stem Cells
Mammalian imprinted Gtl2 protects adult hematopoietic stem cells by restricting metabolic activity in the cells' mitochondria.
Genetic Basis of Fatal Flu Side Effect Discovered
A group of people with fatal H1N1 flu died after their viral infections triggered a deadly hyperinflammatory disorder in susceptible individuals with gene mutations linked to the overactive immune response, according to a recent study.
New Tech Vastly Improves CRISPR/Cas9 Accuracy
A new CRISPR/Cas9 technology developed by scientists at UMass Medical School is precise enough to surgically edit DNA at nearly any genomic location, while avoiding potentially harmful off-target changes typically seen in standard CRISPR gene editing techniques.
The MaxSignal Colistin ELISA Test Kit from Bioo Scientific
Kit can help prevent the antibiotic apocalypse by keeping last resort drugs out of the food supply.
"Good" Mozzie Virus Might Hold Key to Fighting Human Disease
Australian scientists have discovered a new virus carried by one of the country’s most common pest mosquitoes.
Non-Disease Proteins Kill Brain Cells
Scientists at the forefront of cutting-edge research into neurodegenerative diseases such as Alzheimer’s and Parkinson’s have shown that the mere presence of protein aggregates may be as important as their form and identity in inducing cell death in brain tissue.
Closing the Loop on an HIV Escape Mechanism
Research team finds that protein motions regulate virus infectivity.
New Class of RNA Tumor Suppressors Identified
Two short, “housekeeping” RNA molecules block cancer growth by binding to an important cancer-associated protein called KRAS. More than a quarter of all human cancers are missing these RNAs.
Potential Treatment for Life-Threatening Viral Infections Revealed
The findings point to new therapies for Dengue, West Nile and Ebola.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos