|Part of the nature series|
A megacryometeor is a very large chunk of ice which, despite sharing many textural, hydro-chemical, and isotopic features detected in large hailstones, is formed under unusual atmospheric conditions which clearly differ from those of the cumulonimbus cloud scenario (i.e. clear-sky conditions). They are sometimes called huge hailstones, but do not need to form under thunderstorm conditions. Jesús Martínez-Frías, a planetary geologist and astrobiologist at Institute of Geosciences (Spanish : Instituto de Geociencias, IGEO) in the Spanish National Research Council (Spanish : Consejo Superior de Investigaciones Científicas, CSIC) in Madrid, pioneered research into megacryometeors in January 2000 after ice chunks weighing up to 6.6 pounds (3.0 kg) rained on Spain out of cloudless skies for ten days.
More than 50 megacryometeors have been recorded since the year 2000. They vary in mass between 0.5 kilograms (1.1 lb) to several tens of kilograms. One in Brazil weighed in at more than 50 kilograms (110 lb). Chunks about 2 m (6 ft 7 in) in size fell in Scotland on 13 August 1849.
The process that creates megacryometeors is not completely understood, mainly with respect to the atmospheric dynamics necessary to produce them. They may have a similar mechanism of formation to that leading to production of hailstones.Scientific studies show that their composition matches normal tropospheric rainwater for the areas in which they fall. In addition, megacryometeors display textural variations of the ice and hydro-chemical and isotopic heterogeneity, which evidence a complex formation process in the atmosphere. It is known that they do not form from airplane toilet leakage because the large chunks of ice that occasionally do fall from airliners are distinctly blue due to the disinfectant used.
Some have speculated that these ice chunks must have fallen from aircraft fuselages −10 to −20 °C (14 to −4 °F). They are sometimes confused with meteors because they can leave small impact craters.after plain water ice accumulating on those aircraft through normal atmospheric conditions has simply broken loose. However, similar events occurred prior to the invention of aircraft. Studies indicate that fluctuations in tropopause, associated with hydration of the lower stratosphere and stratospheric cooling, can be related to their formation. A detailed micro-Raman spectroscopic study made it possible to place the formation of the megacryometeors within a particular range of temperatures:
The Eocene Epoch, lasting from 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the Grande Coupure or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and end of the epoch are well identified, though their exact dates are slightly uncertain., is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope
Hail is a form of solid precipitation. It is distinct from ice pellets, though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets fall generally in cold weather while hail growth is greatly inhibited during cold surface temperatures.
Ice is water frozen into a solid state. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color.
Spectroscopy is the study of the interaction between matter and electromagnetic radiation. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism. Later the concept was expanded greatly to include any interaction with radiative energy as a function of its wavelength or frequency, predominantly in the electromagnetic spectrum, though matter waves and acoustic waves can also be considered forms of radiative energy; recently, with tremendous difficulty, even gravitational waves have been associated with a spectral signature in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO) and laser interferometry. Spectroscopic data are often represented by an emission spectrum, a plot of the response of interest, as a function of wavelength or frequency.
A mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of debris/smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with a nuclear explosion, but any sufficiently energetic detonation or deflagration will produce the same effect. They can be caused by powerful conventional weapons, like thermobaric weapons, including the ATBIP and GBU-43/B Massive Ordnance Air Blast. Some volcanic eruptions and impact events can produce natural mushroom clouds.
Cloud physics is the study of the physical processes that lead to the formation, growth and precipitation of atmospheric clouds. These aerosols are found in the troposphere, stratosphere, and mesosphere, which collectively make up the greatest part of the homosphere. Clouds consist of microscopic droplets of liquid water, tiny crystals of ice, or both. Cloud droplets initially form by the condensation of water vapor onto condensation nuclei when the supersaturation of air exceeds a critical value according to Köhler theory. Cloud condensation nuclei are necessary for cloud droplets formation because of the Kelvin effect, which describes the change in saturation vapor pressure due to a curved surface. At small radii, the amount of supersaturation needed for condensation to occur is so large, that it does not happen naturally. Raoult's law describes how the vapor pressure is dependent on the amount of solute in a solution. At high concentrations, when the cloud droplets are small, the supersaturation required is smaller than without the presence of a nucleus.
Polar stratospheric clouds (PSCs) are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 m (49,000–82,000 ft). They are best observed during civil twilight, when the Sun is between 1 and 6 degrees below the horizon, as well as in winter and in more northerly latitudes. One main type of PSC is made up mostly of supercooled droplets of water and nitric acid and is implicated in the formation of ozone holes. The other main type consists only of frozen ice crystals and is not considered harmful. This type of PSC is also referred to as nacreous.
The Max Planck Institute for Chemistry is a non-university research institute under the auspices of the Max Planck Society. It is based in Mainz.
The Arthur L. Day Prize and Lectureship is awarded by the U.S. National Academy of Sciences "to a scientist making new contributions to the physics of the Earth whose four to six lectures would prove a solid, timely, and useful addition to the knowledge and literature in the field." The prize was established by the physicist Arthur L. Day.
Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes.
The term Middle Miocene disruption, alternatively the Middle Miocene extinction or Middle Miocene extinction peak, refers to a wave of extinctions of terrestrial and aquatic life forms that occurred around the middle of the Miocene, roughly 14 million years ago, during the Langhian stage of the Miocene. This era of extinction is believed to have been caused by a relatively steady period of cooling that resulted in the growth of ice sheet volumes globally, and the reestablishment of the ice of the East Antarctic Ice Sheet (EAIS). Cooling that led to the Middle Miocene disruption is primarily attributed to orbitally paced changes in oceanic and atmospheric circulation due to continental drift. These may have been amplified by CO2 being pulled out of the Earth's atmosphere by organic material before becoming caught in different locations like the Monterey Formation. This period was preceded by the Miocene Climatic Optimum, a period of relative warmth from 18 to 14 Ma.
The atmosphere of Titan is the layer of gases surrounding Titan, the largest moon of Saturn. It is the only thick atmosphere of a natural satellite in the Solar System. Titan's lower atmosphere is primarily composed of nitrogen (94.2%), methane (5.65%), and hydrogen (0.099%). There are trace amounts of other hydrocarbons, such as ethane, diacetylene, methylacetylene, acetylene and propane, and of other gases, such as cyanoacetylene, hydrogen cyanide, carbon dioxide, carbon monoxide, cyanogen, argon and helium. The surface pressure is about 50% higher than Earth at 1.5 bars which is near the triple point of methane and allows there to be gaseous methane in the atmosphere and liquid methane on the surface. The orange color as seen from space is produced by other more complex chemicals in small quantities, possibly tholins, tar-like organic precipitates.
Cloud iridescence or irisation is a colorful optical phenomenon that occurs in a cloud and appears in the general proximity of the Sun or Moon. The colors resemble those seen in soap bubbles and oil on a water surface. It is a type of photometeor. This fairly common phenomenon is most often observed in altocumulus, cirrocumulus, lenticular, and cirrus clouds. They sometimes appear as bands parallel to the edge of the clouds. Iridescence is also seen in the much rarer polar stratospheric clouds, also called nacreous clouds.
The 1947 Sydney hailstorm was a natural disaster which struck Sydney, Australia, on 1 January 1947. The storm cell developed on the morning of New Year's Day, a public holiday in Australia, over the Blue Mountains, hitting the city and dissipating east of Bondi in the mid-afternoon. At the time, it was the most severe storm to strike the city since recorded observations began in 1792.
The Allende meteorite is the largest carbonaceous chondrite ever found on Earth. The fireball was witnessed at 01:05 on February 8, 1969, falling over the Mexican state of Chihuahua. After breaking up in the atmosphere, an extensive search for pieces was conducted and over 2 tonnes (tons) of meteorite were recovered. The availability of large quantities of samples of the scientifically-important chondrite class has enabled numerous investigations by many scientists; it is often described as "the best-studied meteorite in history." The Allende meteorite has abundant, large calcium-aluminium-rich inclusions, which are among the oldest objects formed in the Solar System.
John Hoffman is a space scientist who developed instruments for Apollo 15, Apollo 16, Apollo 17, the Pioneer Venus project, and Giotto mission. He also designed the mass spectrometer for the Phoenix Mars Lander mission in May 2008. He is currently a professor of physics at the University of Texas at Dallas.
Stratospheric sulfur aerosols are sulfur-rich particles which exist in the stratosphere region of the Earth's atmosphere. The layer of the atmosphere in which they exist is known as the Junge layer, or simply the stratospheric aerosol layer. These particles consist of a mixture of sulfuric acid and water. They are created naturally, such as by photochemical decomposition of sulfur-containing gases, e.g. carbonyl sulfide. When present in high levels, e.g. after a strong volcanic eruption such as Mount Pinatubo, they produce a cooling effect, by reflecting sunlight, and by modifying clouds as they fall out of the stratosphere. This cooling may persist for a few years before the particles fall out.
The ability of stratospheric aerosols to create a global dimming effect has made them a possible candidate for use in solar radiation management climate engineering projects to limit the effect and impact of climate change due to rising levels of greenhouse gases. Delivery of precursor sulfide gases such as sulfuric acid, hydrogen sulfide or sulfur dioxide by artillery, aircraft and balloons has been proposed. Non-sulfide substances such as calcite have also been proposed given their benefits to the ozone layer. It appears that this could counter most changes to temperature and precipitation, take effect rapidly, have low direct implementation costs, and be reversible in its direct climatic effects. However, it would do so imperfectly and other effects are possible.
The Alberta Hail Project was a research project sponsored by the Alberta Research Council and Environment Canada to study hailstorm physics and dynamics in order to design and test means for suppressing hail. It ran from 1956 until 1985. The main instrument in this research was an S-band circularly polarized weather radar located at the Red Deer Industrial Airport in central Alberta, Canada.
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.
|Look up megacryometeor in Wiktionary, the free dictionary.|