• Roger J. CHENG at ASRC-
  • (1968-2000)
  • Roger Cheng joined the scientific staff of the Atmospheric Sciences Research Center (ASRC) at the State University of New York at Albany in 1968. There he worked with Vincent Schaefer and many others on the scientific staff of the ASRC. For over thirty years, aided by both the light microscope and the scanning electron microscope, his research interests ranged over a wide variety of problems. His discoveries have been recognized both nationally and internationally.

One of Cheng’s early interests, along with that of Schaefer’s, was the mechanism by which ice particles are produced in clouds. His microscope observations revealed that one way is from the surface of freezing water drops. He found that they carried a negative charge. Years later, this was confirmed by cloud physicists at the Massachusetts Institute of Technology. Cheng has long been interested in the marine sea-salt aerosol. Produced by the sea, primarily by the bursting of bubbles at the surface, the small droplets of seawater are carried high into the marine atmosphere by turbulent mixing and convection. There the droplets can change phase to produce the sea-salt aerosol. It has long been assumed that sea-salt particles are solid spheres and that their mass can be calculated if one knows their diameters. But Cheng, using the scanning electron microscope, found that the particles are not solid but hollow, thus making calculations of their mass very difficult. Cheng’s discovery has been confirmed by German cloud physicists.

An interesting observation made by Cheng was that sulfate particles were ejected from a droplet of seawater when it changed phase. He believes that this phenomenon can play an important role in the global sulfur cycle.

From the Taj Mahal to the Imperial Palace in Peking to numerous cities in the industrialized nations, gases and particles of the world’s atmosphere are rapidly eating away at stone and monuments that have withstood the onslaught of the winds of the centuries. Cheng turned his attention to this problem. His experiments led him to believe that much of the trouble begins when sulfur dioxide reacts with liquid water on the surface of the stone to produce sulfuric acid. Small airborne particles then act as a catalyst in the reaction to change some of the stone to gypsum, a crumbly material much different from the original hard, smooth surface. Air pollution attacks not only stone but leaves on trees and other vegetation. Cheng’s experiments with a scanning electron microscope and an energy-dispersive x-ray micro-spectrometer have revealed that a concentration of industrial particulates and small sulfate crystals are found around the damaged area of the leaves. As with the case of damage to stone, the leaves are damaged primarily by sulfuric acid.

Few scientists have traveled as often as Cheng has to scientific conferences around the world. Although President Nixon may have been responsible for opening the doors to cultural and scientific interaction with the People’s Republic of China, Cheng wasted little time in passing through these doors. In his first visit since he left China many years earlier, Cheng presented fourteen seminars and visited twenty-five universities, research institutes, and government and local environmental protection agencies. In the other direction, Cheng has visited and given seminars and presentations at many universities and international conferences in Europe and Russia. Cheng has received international recognition not only for the science revealed by his photographs obtained by the light microscope and the scanning electron microscope, but also for their elegance and beauty. For years these photographs have been in wide demand by editors of both popular and scientific magazines. One graced the cover of SCIENCE magazine.

In addition to his published articles, Cheng was a co-author of the book Air Pollution and Control. This book, endorsed by the Director of the Chinese National Environmental Protection Bureau, was published in Chinese by the Chinese Environmental Science Service. It was distributed to national, state, and city environmental officers as a handbook and to universities and research institutes as reference materials. The book was the first of its kind in the Chinese language.

In 1978 Cheng received the Chancellor’s Award for Excellence in Professional Service. This high award is granted to University professional service staff members who have demonstrated outstanding job performance.

Although Roger Cheng retired from the Atmospheric Science Research Center in 2000, this has not decreased his enthusiasm for science. He has plans for more visits to China and to other countries. But best of all, he has produced a CD-ROM containing all his papers, magazine covers, and many hundreds of his photographs. This work of a very active lifetime will be encapsulated in this CD-ROM.