Understanding the Formation and Growth of New Atmospheric Particles at the Molecular Level through Laboratory Molecular Beam Experiments

Atmospheric new particle formation (NPF), which exerts comprehensive implications for climate, air quality and human health, has received extensive attention. From molecule to cluster is the initial and most important stage of the nucleation process of atmospheric new particles. However, due to the complexity of the nucleation process and limitations of experimental characterization techniques, there is still a great uncertainty in understanding the nucleation mechanism at the molecular level. Laboratory-based molecular beam methods can experimentally implement the generation and growth of typical atmospheric gas-phase nucleation precursors to nanoscale clusters, characterize the key physical and chemical properties of clusters such as structure and composition, and obtain a series of their physicochemical parameters, including association rate coefficients, electron binding energy, pickup cross section and pickup probability and so on. These parameters can quantitatively illustrate the physicochemical properties of the cluster, and evaluate the effect of different gas phase nucleation precursors on the formation and growth of atmospheric new particles. We review the present literatures on atmospheric cluster formation and reaction employing the experimental method of laboratory molecular beam. The experimental apparatuses were classified and summarized from three aspects of cluster generation, growth and detection processes. Focus of this review is on the properties of nucleation clusters involving different precursor molecules of water, sulfuric acid, nitric acid and NxOy, respectively. We hope this review will provide a deep insight for effects of cluster physicochemical properties on nucleation, and reveal the formation and growth mechanism of atmospheric new particle at the molecular level.

The great tambora eruption in 1815 and its aftermath

Quantitative analytical methods are used to reconstruct the course of events during and after the cataclysmic eruption of Mount Tambora, Indonesia, on 10 and 11 April 1815. This was the world's greatest ash eruption (so far as is definitely known) since the end of the last Ice Age. This synthesis is based on data and methods from the fields of volcanology, oceanography, glaciology, meteorology, climatology, astronomy, and history.

Sulfuric Acid Droplet Formation and Growth in the Stratosphere After the 1982 Eruption of El Chichon

The eruption of El Chichón Volcano in March and April 1982 resulted in the nucleation of large numbers of new sulfuric acid droplets and an increase by nearly an order of magnitude in the size of the preexisting particles in the stratosphere. Nearly 10(7) metric tons of sulfuric acid remained in the stratosphere by the end of 1982, about 40 times as much as was deposited by Mount St. Helens in 1980.

Size Distributions and Mineralogy of Ash Particles in the Stratosphere from Eruptions of Mount St. Helens

Samples from the stratosphere obtained by U-2 aircraft after the first three major eruptions of Mount St. Helens contained large globules of liquid acid and ash. Because of their large size, these globules had disappeared from the lower stratosphere by late June 1980, leaving behind only smaller acid droplets. Particle-size distributions and mineralogy of the stratospheric ash grains demonstrate in-homogeneity in the eruption clouds.

Stratospheric Sulfuric Acid Layer: Evidence for an Anthropogenic Component

Recent measurements of small aerosol particles in the stratosphere over Laramie, Wyoming, indicate low-concentration background conditions. A comparison of measurements made some 20 years ago with the present background concentration reveals the possibility of an increase of 9 percent per year. Since the aerosol particles are predominantly sulfuric acid droplets which form in the stratosphere from tropospheric sulfur-containing gases, such an increase may be related to man-made sulfur emissions.