Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Pollution teams with thunderclouds to warm atmosphere

New simulation study shows that atmosphere warms when pollution intensifies storms

Pollution is warming the atmosphere through summer thunderstorm clouds, according to a computational study published May 10 in Geophysical Research Letters. How much the warming effect of these clouds offsets the cooling that other clouds provide is not yet clear. To find out, researchers need to incorporate this new-found warming into global climate models.

Pollution strengthens thunderstorm clouds, causing their anvil-shaped tops to spread out high in the atmosphere and capture heat -- especially at night, said lead author and climate researcher Jiwen Fan of the Department of Energy's Pacific Northwest National Laboratory.

"Global climate models don't see this effect because thunderstorm clouds simulated in those models do not include enough detail," said Fan. "The large amount of heat trapped by the pollution-enhanced clouds could potentially impact regional circulation and modify weather systems."

Clouds are one of the most poorly understood components of Earth's climate system. Called deep convective clouds, thunderstorm clouds reflect a lot of the sun's energy back into space, trap heat that rises from the surface, and return evaporated water back to the surface as rain, making them an important part of the climate cycle.

To more realistically model clouds on a small scale, such as in this study, researchers use the physics of temperature, water, gases and aerosols -- tiny particles in the air such as pollution, salt or dust on which cloud droplets form.

In large-scale models that look at regions or the entire globe, researchers substitute a stand-in called a parameterization to account for deep convective clouds. The size of the grid in global models can be a hundred times bigger than an actual thunderhead, making a substitute necessary.

However, thunderheads are complicated, dynamic clouds. Coming up with an accurate parameterization is important but has been difficult due to their dynamic nature.

Inside a thunderstorm cloud, warm air rises in updrafts, pushing tiny aerosols from pollution or other particles upwards. Higher up, water vapor cools and condenses onto the aerosols to form droplets, building the cloud. At the same time, cold air falls, creating a convective cycle. Generally, the top of the cloud spreads out like an anvil.

Previous work showed that when it's not too windy, pollution leads to bigger clouds . This occurs because more pollution particles divide up the available water for droplets, leading to a higher number of smaller droplets that are too small to rain. Instead of raining, the small droplets ride the updrafts higher, where they freeze and absorb more water vapor. Collectively, these events lead to bigger, more vigorous convective clouds that live longer.

Now, researchers from PNNL, Hebrew University in Jerusalem and the University of Maryland took to high-performance computing to study the invigoration effect on a regional scale.

To find out which factors contribute the most to the invigoration, Fan and colleagues set up computer simulations for two different types of storm systems: warm summer thunderstorms in southeastern China and cool, windy frontal systems on the Great Plains of Oklahoma. The data used for the study was collected by different DOE Atmospheric Radiation Measurement facilities.

The simulations had a resolution that was high enough to allow the team to see the clouds develop. The researchers then varied conditions such as wind speed and air pollution.

Fan and colleagues found that for the warm summer thunderstorms, pollution led to stronger storms with larger anvils. Compared to the cloud anvils that developed in clean air, the larger anvils both warmed more -- by trapping more heat -- and cooled more -- by reflecting additional sunlight back to space. On average, however, the warming effect dominated.

The springtime frontal clouds did not have a similarly significant warming effect. Also, increasing the wind speed in the summer clouds dampened the invigoration by aerosols and led to less warming.

This is the first time researchers showed that pollution increased warming by enlarging thunderstorm clouds. The warming was surprisingly strong at the top of the atmosphere during the day when the storms occurred. The pollution-enhanced anvils also trapped more heat at night, leading to warmer nights.

"Those numbers for the warming are very big," said Fan, "but they are calculated only for the exact day when the thunderstorms occur. Over a longer time-scale such as a month or a season, the average amount of warming would be less because those clouds would not appear everyday."

Next, the researchers will look into these effects on longer time scales. They will also try to incorporate the invigoration effect in global climate models.

The research was supported by the U.S. Department of Energy Office of Science. The data from China were gathered under a bilateral agreement with the China Ministry of Sciences and Technology.

Reference: Jiwen Fan, Daniel Rosenfeld, Yanni Ding, L. Ruby Leung, and Zhanqing Li, 2012. Potential Aerosol Indirect Effects on Atmospheric Circulation and Radiative Forcing through Deep Convection, Geophys. Res. Lett. May 10, DOI 10.1029/2012GL051851 (

Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. PNNL employs 4,700 staff, has an annual budget of nearly $1.1 billion, and has been managed for the U.S. Department of Energy by Ohio-based Battelle since the laboratory's inception in 1965. For more, visit the PNNL's News Center, or follow PNNL on Facebook, LinkedIn and Twitter.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

Mary Beckman | EurekAlert!
Further information:

More articles from Earth Sciences:

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

nachricht UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>