The sulfate or sulphate ion is a polyatomic anion with the empirical formula SO2−4. Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many are prepared from that acid.
A ceilometer is a device that uses a laser or other light source to determine the height of a cloud ceiling or cloud base. Ceilometers can also be used to measure the aerosol concentration within the atmosphere. A ceilometer that uses laser light is a type of atmospheric lidar instrument.
The first systematic measurements of global direct irradiance at the Earth's surface began in the 1950s. A decline in irradiance was soon observed, and it was given the name of global dimming. It continued from 1950s until 1980s, with an observed reduction of 4–5% per decade, even though solar activity did not vary more than the usual at the time. Global dimming has instead been attributed to an increase in atmospheric particulate matter, predominantly sulfate aerosols, as the result of rapidly growing air pollution due to post-war industrialization. After 1980s, global dimming started to reverse, alongside reductions in particulate emissions, in what has been described as global brightening, although this reversal is only considered "partial" for now. The reversal has also been globally uneven, as the dimming trend continued during the 1990s over some mostly developing countries like India, Zimbabwe, Chile and Venezuela. Over China, the dimming trend continued at a slower rate after 1990, and did not begin to reverse until around 2005.
Cloud condensation nuclei (CCNs), also known as cloud seeds, are small particles typically 0.2 µm, or one hundredth the size of a cloud droplet. CCNs are a unique subset of aerosols in the atmosphere on which water vapour condenses. This can affect the radiative properties of clouds and the overall atmosphere. Water requires a non-gaseous surface to make the transition from a vapour to a liquid; this process is called condensation.
Stratospheric aerosol injection is a proposed method of solar geoengineering to reduce global warming. This would introduce aerosols into the stratosphere to create a cooling effect via global dimming and increased albedo, which occurs naturally from volcanic winter. It appears that stratospheric aerosol injection, at a moderate intensity, could counter most changes to temperature and precipitation, take effect rapidly, have low direct implementation costs, and be reversible in its direct climatic effects. The Intergovernmental Panel on Climate Change concludes that it "is the most-researched [solar geoengineering] method, with high agreement that it could limit warming to below 1.5 °C (2.7 °F)." However, like other solar geoengineering approaches, stratospheric aerosol injection would do so imperfectly and other effects are possible, particularly if used in a suboptimal manner.
Particulates or atmospheric particulate matter are microscopic particles of solid or liquid matter suspended in the air. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.
An ice nucleus, also known as an ice nucleating particle (INP), is a particle which acts as the nucleus for the formation of an ice crystal in the atmosphere.
Aerosol mass spectrometry is the application of mass spectrometry to the analysis of the composition of aerosol particles. Aerosol particles are defined as solid and liquid particles suspended in a gas (air), with size range of 3 nm to 100 μm in diameter and are produced from natural and anthropogenic sources, through a variety of different processes that include wind-blown suspension and combustion of fossil fuels and biomass. Analysis of these particles is important owing to their major impacts on global climate change, visibility, regional air pollution and human health. Aerosols are very complex in structure, can contain thousands of different chemical compounds within a single particle, and need to be analysed for both size and chemical composition, in real-time or off-line applications.
Kimberly A. Prather is an American atmospheric chemist. She is a distinguished chair in atmospheric chemistry and a distinguished professor at the Scripps Institution of Oceanography and department of chemistry and biochemistry at UC San Diego. Her work focuses on how humans are influencing the atmosphere and climate. In 2019, she was elected a member of the National Academy of Engineering for technologies that transformed understanding of aerosols and their impacts on air quality, climate, and human health. In 2020, she was elected as a member of the National Academy of Sciences. She is also an elected Fellow of the American Philosophical Society, American Geophysical Union, the American Association for the Advancement of Science, American Philosophical Society, and the American Academy of Arts and Sciences.
Rebecca Suzanne Hornbrook is an atmospheric chemist at the National Center for Atmospheric Research (NCAR). She currently holds the position of Project Scientist II while also belonging to a variety of groups based out of NCAR, UCAR, and NASA. She is notable for her work as one of the leading experts in Volatile organic compounds (VOCs) while possessing an interest in air quality, biosphere-atmosphere interactions, chemical kinetics, and photochemistry.
Johannes "Jos" Lelieveld is a Dutch atmospheric chemist. Since 2000, he has been a Scientific Member of the Max Planck Society and director of the Atmospheric Chemistry Department at the Max Planck Institute for Chemistry in Mainz. He is also professor at the University of Mainz and at the Cyprus Institute in Nicosia.
The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) was a five-year scientific research program that investigated aspects of phytoplankton dynamics in ocean ecosystems, and how such dynamics influence atmospheric aerosols, clouds, and climate. The study focused on the sub-arctic region of the North Atlantic Ocean, which is the site of one of Earth's largest recurring phytoplankton blooms. The long history of research in this location, as well as relative ease of accessibility, made the North Atlantic an ideal location to test prevailing scientific hypotheses in an effort to better understand the role of phytoplankton aerosol emissions on Earth's energy budget.
Lynn Russell is a professor of atmospheric chemistry at the Scripps Institute of Oceanography a division of the University of California, San Diego in La Jolla, California.
Julia Yvonne Schmale is a German environmental scientist. She is a specialist in the micro-physical makeup of the atmosphere, in particular aerosols and their interaction with clouds. She is a professor at EPFL and the head of the Extreme Environments Research Laboratory (EERL). She is a participant in the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expeditions.
Patricia K. Quinn is a atmospheric chemist working at the National Oceanic and Atmospheric Agency's Pacific Marine Environmental Lab. She is known for her work on the impact of atmospheric aerosol particles on air quality and climate.
Kerri Pratt is an American chemist who is associate professor of chemistry at the University of Michigan. Her research considers atmospheric chemistry and how it impacts human health. She studies the interactions of atmospheric gases using mass spectrometry based techniques.
Vivian Faye McNeill is an American atmospheric chemist who is professor of chemical engineering at Columbia University. She leads the University's initiative Clean Air Toolbox for Cities. McNeill provided expert guidance on aerosols and ventilation throughout the COVID-19 pandemic.
Colin Dermot O'Dowd is an Irish physicist and atmospheric scientist.
John Maurice Campbell Plane,, , is a British atmospheric chemist, currently Professor of Atmospheric Chemistry at the University of Leeds. His research investigates planetary atmospheres using a range of theoretical and experimental techniques.
Delphine Farmer is a Canadian chemist who is a professor at the Colorado State University. Her research considers the development of scientific instruments for atmospheric science. She was awarded the American Geophysical Union Atmospheric Sciences Ascent Award in 2022.
