Research is getting closer to understanding critical nucleus in haze formation

June 16, 2010

Haze, scientifically known as atmospheric aerosols - microscopic particles suspended in the Earth's atmosphere - represents a major environmental problem because it degrades visibility, affects human health and influences the climate. Despite its profound impacts, how the haze is formed is not fully understood, says a Texas A&M University professor of atmospheric sciences and chemistry who has studied air chemistry for more than 20 years.

Professor Renyi Zhang published his work in the June 11 issue of Science magazine, summarizing recent findings and new research directions that could pave the way for a better understanding of formation.

"Aerosols, also referred to as , influence climate by absorbing and reflecting solar radiation and modifying cloud formation," he explains. "A better understanding of how aerosols form in the will greatly improve climate models.

"But, formation of aerosols in the atmosphere is not fully understood, particularly at the molecular level, creating one of the largest sources of uncertainty in climate predictions," he adds.

For aerosols to form, the bonding particles must cross an energy threshold, which the scientists call nucleation barrier. Once the barrier is crossed, aerosol formation can happen spontaneously, he notes.

The interaction between organic acids and sulfuric acid can facilitate the crossing of the barrier by creating a critical nucleus, the Texas A&M professor says in the Science article.

Large amounts of organic gases are emitted to the atmosphere by plants, industry and automobiles and form organic acids; sulfur dioxide, on the other hand, are produced by human activities, such as burning coals, and then form sulfuric acid.

To better understand aerosol formation, scientists need to predict the nucleation rate based on knowledge of the composition of the critical nucleus, Zhang explains.

This knowledge can be obtained by combining theoretical approaches with "measurements of the size and chemical composition of freshly nucleated nanoparticles in the laboratory and in the field," Zhang notes.

Understanding and eventually controlling aerosol formation may help the environment, benefit human health and improve climate prediction, he says.

Explore further: Study Finds Stronger Link Between Human Activity And Particulate Pollution

Related Stories

Invisible gases form most organic haze in urban, rural areas

July 9, 2007

A new study involving the University of Colorado at Boulder shows that invisible, reactive gases hovering over Earth's surface, not direct emissions of particulates, form the bulk of organic haze in both urban and rural areas ...

Pollution dims skies as well as befouling the air

March 12, 2009

A University of Maryland-led team has compiled the first decades-long database of aerosol measurements over land, making possible new research into how air pollution changes affect climate change.

Man-Made Activities Affect Blue Haze (w/ Video)

October 6, 2009

(PhysOrg.com) -- "Blue haze," a common occurrence that appears over heavily forested areas around the world, is formed by natural emissions of chemicals, but human activities can worsen it to the point of affecting the world's ...

CSU scientist simplifies aerosols for modeling

May 26, 2010

The large number of tiny organic aerosols floating in the atmosphere - emitted from tailpipes and trees alike - share enough common characteristics as a group that scientists can generalize their makeup and how they change ...

Recommended for you

Study calculates the speed of ice formation

August 3, 2015

Researchers at Princeton University have for the first time directly calculated the rate at which water crystallizes into ice in a realistic computer model of water molecules. The simulations, which were carried out on supercomputers, ...

'Snowball earth' might be slushy

August 3, 2015

Imagine a world without liquid water—just solid ice in all directions. It would certainly not be a place that most life forms would like to live.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.