The stratosphere is the second-lowest layer of the atmosphere of Earth, located above the troposphere and below the mesosphere. The stratosphere is composed of stratified temperature zones, with the warmer layers of air located higher and the cooler layers lower. The increase of temperature with altitude is a result of the absorption of the Sun's ultraviolet (UV) radiation by the ozone layer, where ozone is exothermically photolyzed into oxygen in a cyclical fashion. This temperature inversion is in contrast to the troposphere, where temperature decreases with altitude, and between the troposphere and stratosphere is the tropopause border that demarcates the beginning of the temperature inversion.
Ground-level ozone (O3), also known as surface-level ozone and tropospheric ozone, is a trace gas in the troposphere (the lowest level of the Earth's atmosphere), with an average concentration of 20–30 parts per billion by volume (ppbv), with close to 100 ppbv in polluted areas. Ozone is also an important constituent of the stratosphere, where the ozone layer (2 to 8 parts per million ozone) exists which is located between 10 and 50 kilometers above the Earth's surface. The troposphere extends from the ground up to a variable height of approximately 14 kilometers above sea level. Ozone is least concentrated in the ground layer (or planetary boundary layer) of the troposphere. Ground-level or tropospheric ozone is created by chemical reactions between NOx gases (oxides of nitrogen produced by combustion) and volatile organic compounds (VOCs). The combination of these chemicals in the presence of sunlight form ozone. Its concentration increases as height above sea level increases, with a maximum concentration at the tropopause. About 90% of total ozone in the atmosphere is in the stratosphere, and 10% is in the troposphere. Although tropospheric ozone is less concentrated than stratospheric ozone, it is of concern because of its health effects. Ozone in the troposphere is considered a greenhouse gas, and as such contribute to global warming. as reported in IPCC reports. Actually, tropospheric ozone is considered the third most important greenhouse gas after CO2 and CH4, as indicated by estimates of its radiative forcing.
Mario José Molina-Pasquel Henríquez was a Mexican physical chemist. He played a pivotal role in the discovery of the Antarctic ozone hole, and was a co-recipient of the 1995 Nobel Prize in Chemistry for his role in discovering the threat to the Earth's ozone layer from chlorofluorocarbon (CFC) gases. He was the first Mexican-born scientist to receive a Nobel Prize in Chemistry and the third Mexican-born person to receive a Nobel prize.
Paul Jozef Crutzen was a Dutch meteorologist and atmospheric chemist. In 1995, he was awarded the Nobel Prize in Chemistry alongside Mario Molina and Frank Sherwood Rowland for their work on atmospheric chemistry and specifically for his efforts in studying the formation and decomposition of atmospheric ozone. In addition to studying the ozone layer and climate change, he popularized the term Anthropocene to describe a proposed new epoch in the Quaternary period when human actions have a drastic effect on the Earth. He was also amongst the first few scientists to introduce the idea of a nuclear winter to describe the potential climatic effects stemming from large-scale atmospheric pollution including smoke from forest fires, industrial exhausts, and other sources like oil fires.
Susan Solomon is an American atmospheric chemist, working for most of her career at the National Oceanic and Atmospheric Administration (NOAA). In 2011, Solomon joined the faculty at the Massachusetts Institute of Technology, where she serves as the Ellen Swallow Richards Professor of Atmospheric Chemistry & Climate Science. Solomon, with her colleagues, was the first to propose the chlorofluorocarbon free radical reaction mechanism that is the cause of the Antarctic ozone hole. Her most recent book, Solvable: how we healed the earth, and how we can do it again (2024) focuses on solutions to current problems, as do books by data scientist Hannah Ritchie, marine biologist, Ayana Elizabeth Johnson and climate scientist Katharine Hayhoe.
The Solar Mesosphere Explorer was a 1980s NASA spacecraft to investigate the processes that create and destroy ozone in Earth's upper atmosphere. The mesosphere is a layer of the atmosphere extending from the top of the stratosphere to an altitude of about 80 km (50 mi). The spacecraft carried five instruments to measure ozone, water vapor, and incoming solar radiation.
Stratospheric aerosol injection (SAI) 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 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.
Ulrich "Uli" Pöschl is an Austrian chemist who was appointed Director of the newly founded Department of Multiphase Chemistry at the Max Planck Institute for Chemistry in Mainz, Germany on 1 October 2012.
Veronica Vaida is a Romanian-Hungarian-American chemist and professor at the University of Colorado Boulder. She is an expert in environmental chemistry and aerosols.
Murry Lewis Salby was an American atmospheric scientist who focused on upper atmospheric wave propagation for most of his early career, and who more recently argued against aspects of the scientific consensus that human activity contributes to climate change. He has written two textbooks, Fundamentals of Atmospheric Physics (1996), and Physics of the Atmosphere and Climate (2011). The latter textbook, building on his first book, offers an overview of the processes controlling the atmosphere of Earth, weather, energetics, and climate physics.
Anne Mee Thompson is an American scientist, who specializes in atmospheric chemistry and climate change. Her work focuses on how human activities have changed the chemistry of the atmosphere, climate forcing, and the Earth's oxidizing capacity. Thompson is an elected fellow of the American Meteorological Society, American Geophysical Union, and AAAS.
Akkihebbal Ramaiah (Ravi) Ravishankara ForMemRS FAAAS FRSC is a scientist specializing in Chemistry and Atmospheric Sciences, and University Distinguished Professor in the Departments of Chemistry and Atmospheric Sciences at Colorado State University, Fort Collins.
Kristie Ann Boering is a Professor of Earth and Planetary Science and the Lieselotte and David Templeton Professor of Chemistry at University of California, Berkeley. She studies atmospheric chemistry and mass transport in the extraterrestrial atmosphere using kinetics and photochemistry. Boering was elected a member of the National Academy of Sciences in 2018.
Emily V. Fischer is an atmospheric chemist and an associate professor in the department of atmospheric science at Colorado State University. She earned notoriety from her work on the WE-CAN project and on PAN, specifically its role in changing the distribution of oxidants in the troposphere. She has received many honors including the prestigious James B. Macelwane Medal which is "given annually to three to five early career scientists in recognition of their significant contributions to Earth and space science." Fischer is also a role model and activist in galvanizing support for women in STEM fields.
Mian Chin is a Chinese atmospheric chemist. She is a physical scientist in the atmospheric chemistry and dynamics laboratory in the earth science division at Goddard Space Flight Center. Her research includes aerosol-cloud-chemistry-climate interactions. She received the NASA Exceptional Achievement Medal in 2005.
Nadine Unger is a Professor of Atmospheric Chemistry at the University of Exeter. She has studied the role of human activities and forests on the Earth's climate.
José Luis Jiménez-Palacios is a Spanish–American chemist and engineer. As a professor of chemistry at the University of Colorado Boulder, Jimenez contributed to the establishment of the Aerodyne Aerosol Mass Spectrometer, an instrument for real-time analysis of aerosol size and composition.
Cora Einterz Randall is an atmospheric scientist known for her research on particles in the atmosphere, particularly in polar regions.
John W. Birks is an American atmospheric chemist and entrepreneur who is best known for co-discovery with Paul Crutzen of the potential atmospheric effects of nuclear war known as nuclear winter. His most recent awards include the 2019 Haagen-Smit Clean Air Award for his contributions to atmospheric chemistry and the 2022 Future of Life Award for discovery of the nuclear winter effect.
Margaret A. Tolbert is an American atmospheric chemist, specializing in polar stratospheric clouds.
