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49-406: The tephra typically glows red when leaving the vent, but its surface cools and assumes a dark to black colour and may significantly solidify before impact. The tephra accumulates in the vicinity of the vent, forming a cinder cone . Cinder is the most common product; the amount of volcanic ash is typically rather minor. The lava flows are more viscous , and therefore shorter and thicker, than

98-435: A correct description of the source of stratospheric ozone and its ability to generate heat within the stratosphere; he also wrote that ozone may be destroyed by reacting with atomic oxygen, making two molecules of molecular oxygen. We now know that there are additional ozone loss mechanisms and that these mechanisms are catalytic, meaning that a small amount of the catalyst can destroy a great number of ozone molecules. The first

147-484: A phenomenon called Rossby-wave pumping. An interesting feature of stratospheric circulation is the quasi-biennial oscillation (QBO) in the tropical latitudes, which is driven by gravity waves that are convectively generated in the troposphere . The QBO induces a secondary circulation that is important for the global stratospheric transport of tracers, such as ozone or water vapor . Another large-scale feature that significantly influences stratospheric circulation

196-659: A single buoyant jet of magma from the Earth's core instead of cracks in the ocean floor. This is reflected in the decreasing age of the islands east to west from Fuerteventura to El Hierro. There are about 60 volcanoes in Ethiopia, located in east Africa. In Southern Ethiopia, the Omo Kibish Rock Formation is composed of layers of tephra and sediment. Within these layers, several fossils have been discovered. In 1967, 2 Homo sapiens fossils were discovered in

245-526: A single eruption—to create a chronological framework in which paleoenvironmental or archaeological records can be placed. Often, when a volcano explodes, biological organisms are killed and their remains are buried within the tephra layer. These fossils are later dated by scientists to determine the age of the fossil and its place within the geologic record. Tephra is any sized or composition pyroclastic material produced by an explosive volcanic eruption and precise geological definitions exist. It consists of

294-560: A variety of materials, typically glassy particles formed by the cooling of droplets of magma , which may be vesicular, solid or flake-like, and a varying proportions of crystalline and mineral components originating from the mountain and the walls of the vent. As the particles fall to the ground, they are sorted to a certain extent by the wind and gravitational forces and form layers of unconsolidated material. The particles are further moved by ground surface or submarine water flow. The distribution of tephra following an eruption usually involves

343-484: Is a religious site for locals. It last erupted in 1903. In 2017, new fossil evidence was discovered that determined the date of Paektu Mountain's first eruption, which had been a mystery. A team of scientists directed by Dr. Clive Oppenheimer, British volcanologist , discovered a larch trunk embedded within Paektu Mountain. After radiocarbon dating, the larch was determined to be 264 years old which coincides with

392-401: Is caused by variations in the jet stream and other local wind shears, although areas of significant convective activity ( thunderstorms ) in the troposphere below may produce turbulence as a result of convective overshoot . On October 24, 2014, Alan Eustace became the record holder for reaching the altitude record for a manned balloon at 135,890 ft (41,419 m). Eustace also broke

441-521: Is due to the reaction of hydroxyl radicals (•OH) with ozone. •OH is formed by the reaction of electrically excited oxygen atoms produced by ozone photolysis, with water vapor. While the stratosphere is dry, additional water vapor is produced in situ by the photochemical oxidation of methane (CH 4 ). The HO 2 radical produced by the reaction of OH with O 3 is recycled to OH by reaction with oxygen atoms or ozone. In addition, solar proton events can significantly affect ozone levels via radiolysis with

490-466: Is over forty thousand years old and has erupted 11 times since 1800. In South America , there are several historic active volcanoes. In southern Chile , the Chaitén volcano erupted in 2011 adding 160 meters to its rim. Prehistoric weapons and tools, formed from obsidian tephra blocks, were dated at 5,610 years ago and were discovered 400 km away. Due to the location of the subduction zone of

539-487: Is the breaking planetary waves resulting in intense quasi-horizontal mixing in the midlatitudes. This breaking is much more pronounced in the winter hemisphere where this region is called the surf zone. This breaking is caused due to a highly non-linear interaction between the vertically propagating planetary waves and the isolated high potential vorticity region known as the polar vortex . The resultant breaking causes large-scale mixing of air and other trace gases throughout

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588-581: Is used in broad context within an account by Aristotle of an eruption on Vulcano (Hiera) in Meteorologica . The release of tephra into the troposphere affects the environment physically and chemically. Physically, volcanic blocks damage local flora and human settlements. Ash damages communication and electrical systems, coats forests and plant life, reducing photosynthesis , and pollutes groundwater . Tephra changes below- and above-ground air and water movement. Chemically, tephra release can affect

637-533: The Canary Islands . The most recent El Hierro eruption occurred underwater, in 2011, and caused earthquakes and landslides throughout the Canary Islands. Instead of ash, floating rocks, 'restingolites' were released after every eruption. After the 2011 eruption, fossils of single-celled marine organisms were found in the restingolites verifying the origin theory that Canary Island growth comes from

686-507: The Omo Kibish Formation by Richard Leaky , a paleoanthropologist. After radiocarbon dating, they were determined to be 195 thousand years old. Other mammals discovered in the formation include Hylochoerus meinertzhageni (forest hog) and Cephalophus (antelope). In Asia, several volcanic eruptions are still influencing local cultures today. In North Korea, Paektu Mountain , a stratovolcano, first erupted in 946 AD and

735-704: The Roman culture. Also, in Italy, Stromboli volcano , a stratovolcano, last erupted in July 2019. Several volcanic eruptions have been studied in North America . On 18 May 1980, Mount St. Helens , a stratovolcano in Washington state , erupted, spreading five hundred million tons of tephra ash across Washington, Oregon, Montana and Idaho causing earthquakes , rockslides , and megatsunami which severely altered

784-604: The UV-C region, at wavelengths shorter than about 240 nm. Radicals produced from the homolytically split oxygen molecules combine with molecular oxygen to form ozone. Ozone in turn is photolysed much more rapidly than molecular oxygen as it has a stronger absorption that occurs at longer wavelengths, where the solar emission is more intense. Ozone (O 3 ) photolysis produces O and O 2 . The oxygen atom product combines with atmospheric molecular oxygen to reform O 3 , releasing heat. The rapid photolysis and reformation of ozone heat

833-527: The water cycle . Tephra particles can cause ice crystals to grow in clouds, which increases precipitation . Nearby watersheds and the ocean can experience elevated mineral levels, especially iron , which can cause explosive population growth in plankton communities. This, in turn, can result in eutrophication . In addition to tephrochronology, tephra is used by a variety of scientific disciplines including geology , paleoecology , anthropology , and paleontology , to date fossils, identify dates within

882-764: The "Lighthouse of the Mediterranean". The most energetic Strombolian eruptions are sometimes termed "Violent Strombolian" by volcanologists. Such eruptions are associated with higher magma gas content, leading to a turbulent churn flow regime in the conduit, producing stronger and much more frequent explosions. Violent Strombolian eruptions are more explosive in nature than their regular counterparts (up to VEI 3), and may produce sustained lava fountains, long distance lava flows, eruption columns several kilometres in height, and heavy ash fallout. Rarely, Violent Strombolian eruptions may transition into Subplinian eruptions . Examples of Violent Strombolian activity include

931-596: The 946 AD eruption. Its tree rings are being studied and many new discoveries are being made about North Korea during that time. In northeastern China, a large volcanic eruption in the early Cretaceous caused the fossilization of an entire ecosystem known as the Jehol Biota when powerful pyroclastic flows inundated the area. The deposits include many perfectly preserved fossils of dinosaurs , birds , mammals , reptiles , fish , frogs , plants , and insects . Europe's volcanoes provide unique information about

980-402: The altitudes of normal lightning and storm clouds. Upper-atmospheric lightning is believed to be electrically induced forms of luminous plasma . Lightning extending above the troposphere into the stratosphere is referred to as blue jet , and that reaching into the mesosphere as red sprite . Bacterial life survives in the stratosphere, making it a part of the biosphere . In 2001, dust

1029-489: The cold European winters of the 1960s. Stratospheric warming of the polar vortex results in its weakening. When the vortex is strong, it keeps the cold, high-pressure air masses contained in the Arctic ; when the vortex weakens, air masses move equatorward, and results in rapid changes of weather in the mid latitudes. Upper-atmospheric lightning is a family of short-lived electrical-breakdown phenomena that occur well above

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1078-597: The conduit system is not strongly affected by the eruptive activity, so that the eruptive system can repeatedly reset itself. Monogenetic cones usually erupt in the Strombolian style. For example, the Parícutin volcano erupted continuously between 1943–1952, Mount Erebus , Antarctica has produced Strombolian eruptions for at least many decades, and Stromboli itself has been producing Strombolian eruptions for over two thousand years. The Romans referred to Stromboli as

1127-519: The cooler layers lower (closer to the planetary surface of the Earth). 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

1176-550: The corresponding Hawaiian eruptions ; it may or may not be accompanied by production of pyroclastic rock . Instead the gas coalesces into bubbles, called gas slugs , that grow large enough to rise through the magma column, bursting near the top due to the decrease in pressure and throwing magma into the air. Each episode thus releases volcanic gases, sometimes as frequently as a few minutes apart. Gas slugs can form as deep as 3 kilometers, making them difficult to predict. Strombolian eruptive activity can be very long-lasting because

1225-533: The discovery of an isothermal layer at around 11–14 km (6.8-8.7 mi), which is the base of the lower stratosphere. This was based on temperature profiles from mostly unmanned and a few manned instrumented balloons. The mechanism describing the formation of the ozone layer was described by British mathematician and geophysicist Sydney Chapman in 1930, and is known as the Chapman cycle or ozone–oxygen cycle . Molecular oxygen absorbs high energy sunlight in

1274-470: The eastern Pacific's Nazca Plate, there are twenty one active volcanoes in southern Peru . In 2006, fossils, found under a layer of volcanic ash in Peru, were excavated by a team of paleontologists led by Mark D. Uhen, professor at George Mason University. The fossils were identified as 3 different types of archaeocetes, prehistoric whales, and are older than 36.61 million years which, as of 2011, makes them

1323-509: The fossils record, and learn about prehistoric cultures and ecosystems. For example, carbonatite tephra found at Oldoinyo Lengai (a volcano in the East African Rift Valley) has buried and preserved fossilized footprints of humans near the site of the eruption. Under certain conditions, volcanic blocks can be preserved for billions of years and can travel up to 400 km away from the eruption. Volcanic eruptions around

1372-425: The ground, they remain as tephra unless hot enough to fuse into pyroclastic rock or tuff . When a volcano explodes, it releases a variety of tephra including ash, cinders, and blocks. These layers settle on the land and, over time, sedimentation occurs incorporating these tephra layers into the geologic record. Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from

1421-489: The history of Italy . One example is Mount Vesuvius , a stratovolcano located in southern Italy, which last erupted in March 1944. Earlier, in 79 AD, in an eruption which lasted 12 to 18 hours, Vesuvius had covered the city of Pompeii in molten lava, ash, pumice, volcanic blocks, and toxic gases. Much of the town was preserved and organic materials fossilized by the volcanic ash, and that has provided valuable information about

1470-467: The largest boulders falling to the ground quickest, therefore closest to the vent, while smaller fragments travel further – ash can often travel for thousands of miles, even circumglobal, as it can stay in the stratosphere for days to weeks following an eruption. When large amounts of tephra accumulate in the atmosphere from massive volcanic eruptions (or from a multitude of smaller eruptions occurring simultaneously), they can reflect light and heat from

1519-566: The lift by the lift-to-drag ratio .) It also allows the airplane to stay above the turbulent weather of the troposphere. The Concorde aircraft cruised at Mach 2 at about 60,000 ft (18 km), and the SR-71 cruised at Mach 3 at 85,000 ft (26 km), all within the stratosphere. Because the temperature in the tropopause and lower stratosphere is largely constant with increasing altitude, very little convection and its resultant turbulence occurs there. Most turbulence at this altitude

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1568-406: The lower reaches of the stratosphere in temperate latitudes. This optimizes fuel efficiency , mostly due to the low temperatures encountered near the tropopause and low air density, reducing parasitic drag on the airframe . Stated another way, it allows the airliner to fly faster while maintaining lift equal to the weight of the plane. (The fuel consumption depends on the drag, which is related to

1617-492: The midlatitude surf zone. The timescale of this rapid mixing is much smaller than the much slower timescales of upwelling in the tropics and downwelling in the extratropics. During northern hemispheric winters, sudden stratospheric warmings , caused by the absorption of Rossby waves in the stratosphere, can be observed in approximately half of winters when easterly winds develop in the stratosphere. These events often precede unusual winter weather and may even be responsible for

1666-402: The oldest whale fossils discovered. Stratosphere The stratosphere ( / ˈ s t r æ t ə ˌ s f ɪər , - t oʊ -/ ) 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 (closer to outer space ) and

1715-438: The ozone layer allows life to exist on the surface of the planet outside of the ocean. All air entering the stratosphere must pass through the tropopause , the temperature minimum that divides the troposphere and stratosphere. The rising air is literally freeze dried; the stratosphere is a very dry place. The top of the stratosphere is called the stratopause , above which the temperature decreases with height. Sydney Chapman gave

1764-417: The paroxysms of Mt. Etna , the 1943-1952 eruption of Parícutin , the 2021 Cumbre Vieja eruption , and various eruptions of Mt. Vesuvius between 1631 and 1944. Tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts . Once clasts have fallen to

1813-596: The size of the eruption. Tephra fragments are classified by size: The use of tephra layers, which bear their own unique chemistry and character, as temporal marker horizons in archaeological and geological sites, is known as tephrochronology . The word "tephra" and "pyroclast" both derive from Greek : The word τέφρα ( téphra ) means "ash", while pyroclast is derived from the Greek πῦρ ( pyr ), meaning "fire", and κλαστός ( klastós ), meaning "broken in pieces". The word τέφραv (means "ashes")

1862-432: The stratosphere dynamically stable: there is no regular convection and associated turbulence in this part of the atmosphere. However, exceptionally energetic convection processes, such as volcanic eruption columns and overshooting tops in severe supercell thunderstorms , may carry convection into the stratosphere on a very local and temporary basis. Overall, the attenuation of solar UV at wavelengths that damage DNA by

1911-432: The stratosphere is termed as Brewer-Dobson circulation , which is a single-celled circulation, spanning from the tropics up to the poles, consisting of the tropical upwelling of air from the tropical troposphere and the extra-tropical downwelling of air. Stratospheric circulation is a predominantly wave-driven circulation in that the tropical upwelling is induced by the wave force by the westward propagating Rossby waves , in

1960-470: The stratosphere, resulting in a temperature inversion. This increase of temperature with altitude is characteristic of the stratosphere; its resistance to vertical mixing means that it is stratified. Within the stratosphere temperatures increase with altitude (see temperature inversion ) ; the top of the stratosphere has a temperature of about 270 K (−3 °C or 26.6 °F ). This vertical stratification , with warmer layers above and cooler layers below, makes

2009-424: The subsequent formation of OH. Nitrous oxide (N 2 O) is produced by biological activity at the surface and is oxidised to NO in the stratosphere; the so-called NO x radical cycles also deplete stratospheric ozone. Finally, chlorofluorocarbon molecules are photolysed in the stratosphere releasing chlorine atoms that react with ozone giving ClO and O 2 . The chlorine atoms are recycled when ClO reacts with O in

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2058-404: The sun back through the atmosphere, in some cases causing the temperature to drop, resulting in a temporary " volcanic winter ". The effects of acidic rain and snow, the precipitation caused by tephra discharges into the atmosphere, can be seen for years after the eruptions have stopped. Tephra eruptions can affect ecosystems across millions of square kilometres or even entire continents depending on

2107-536: The topography of nearby areas. In Yellowstone National Park , eruption-related flooding caused trees to collapse and wash into lake beds where they fossilized. Nearby forests were flooded, removing bark, leaves, and tree limbs. In 2006, the Augustine Volcano in Alaska erupted generating earthquakes, avalanches , and projected tephra ash approximately two hundred and ninety kilometers away. This dome volcano

2156-636: The tropopause to an average of −15 °C (5.0 °F; 260 K) near the mesosphere. Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly low temperatures in the polar night (winter). Winds in the stratosphere can far exceed those in the troposphere, reaching near 60 m/s (220 km/h; 130 mph) in the Southern polar vortex . In 1902, Léon Teisserenc de Bort from France and Richard Assmann from Germany, in separate but coordinated publications and following years of observations, published

2205-445: The troposphere and stratosphere is the tropopause border that demarcates the beginning of the temperature inversion. Near the equator , the lower edge of the stratosphere is as high as 20 km (66,000 ft; 12 mi), at mid-latitudes around 10 km (33,000 ft; 6.2 mi), and at the poles about 7 km (23,000 ft; 4.3 mi). Temperatures range from an average of −51 °C (−60 °F; 220 K) near

2254-573: The upper stratosphere, or when ClO reacts with itself in the chemistry of the Antarctic ozone hole. Paul J. Crutzen, Mario J. Molina and F. Sherwood Rowland were awarded the Nobel Prize in Chemistry in 1995 for their work describing the formation and decomposition of stratospheric ozone. Commercial airliners typically cruise at altitudes of 9–12 km (30,000–39,000 ft) which is in

2303-400: The world have provided valuable scientific information on local ecosystems and ancient cultures. The Waw an Namus volcano is surrounded by an apron of dark tephra, which has a notable color contrast to the surrounding Sahara Desert . Africa's volcanoes have had an impact on the fossil record. Geographically a part of Africa, El Hierro is a shield volcano and the youngest and smallest of

2352-456: The world records for vertical speed skydiving, reached with a peak velocity of 1,321 km/h (822 mph) and total freefall distance of 123,414 ft (37,617 m) – lasting four minutes and 27 seconds. The stratosphere is a region of intense interactions among radiative, dynamical , and chemical processes, in which the horizontal mixing of gaseous components proceeds much more rapidly than does vertical mixing. The overall circulation of

2401-550: Was collected at a height of 41 kilometres in a high-altitude balloon experiment and was found to contain bacterial material when examined later in the laboratory. Some bird species have been reported to fly at the upper levels of the troposphere. On November 29, 1973, a Rüppell's vulture ( Gyps rueppelli ) was ingested into a jet engine 11,278 m (37,000 ft) above the Ivory Coast . Bar-headed geese ( Anser indicus ) sometimes migrate over Mount Everest , whose summit

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