A mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of debris/smoke and condensed water vapor resulting from a large explosion. The effect is most 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. Mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability; the buoyant mass of gas rises resulting in turbulent vortices curling downward around its edges, forming a temporary vortex ring that draws up a central column with smoke, and/or condensed water vapor to form the "mushroom stem". The mass of gas plus entrained moist air reaches an altitude where it is no longer of lower density than the surrounding air.

The stabilization altitude depends on the profiles of the temperature, dew point, wind shear in the air at and above the starting altitude. Although the term appears to have been coined at the start of the 1950s, mushroom clouds generated by explosions were being described centuries before the atomic era. A contemporary aquatint by an unknown artist of the 1782 Franco-Spanish attack on Gibraltar shows one of the attacking force's floating batteries exploding with a mushroom cloud, after the British defenders set it ablaze by firing heated shot. In 1798, Gerhard Vieth published a detailed and illustrated account of a cloud in the neighborhood of Gotha, "not unlike a mushroom in shape"; the cloud had been observed by legation counselor Lichtenberg a few years earlier on a warm summer afternoon. It was interpreted as an irregular meteorological cloud and seemed to have caused a storm with rain and thunder from a new dark cloud that developed beneath it. Lichtenberg stated to have observed somewhat similar clouds, but none as remarkable.

The 1917 Halifax Explosion produced one. The Times published a report on 1 October 1937 of a Japanese attack on Shanghai in China which generated "a great mushroom of smoke". During World War II, descriptions of mushroom clouds were common; the atomic bomb cloud over Nagasaki, Japan was described in The Times of London of 13 August 1945 as a "huge mushroom of smoke and dust". On 9 September 1945, The New York Times published an eyewitness account of the Nagasaki bombing, written by William L. Laurence, the official newspaper correspondent of the Manhattan Project, who accompanied one of the three aircraft that made the bombing run, he wrote of the bomb producing a "pillar of purple fire", out of the top of which came "a giant mushroom that increased the height of the pillar to a total of 45,000 feet". In 1946, the Operation Crossroads nuclear bomb tests were described as having a "cauliflower" cloud, but a reporter present spoke of "the mushroom, now the common symbol of the atomic age". Mushrooms have traditionally been associated both with life and death and poison, making them a more powerful symbolic connection than, the "cauliflower" cloud.

Mushroom clouds are formed by many sorts of large explosions under earth's gravity, but they are best known for their appearance after nuclear detonations. Without gravity, the explosive's by-product gases would remain spherical. Nuclear weapons are detonated above the ground, to maximize the effect of their spherically expanding fireball and blast wave. After the detonation, the fireball begins to rise into the air, acting on the same principle as a hot-air balloon. One way to analyze the motion, once the hot gas has cleared the ground sufficiently, is as a'spherical cap bubble', as this gives agreement between the rate of rise and observed diameter; as it rises, a Rayleigh–Taylor instability is formed, air is drawn upwards and into the cloud, producing strong air currents known as "afterwinds", inside the head of the cloud, the hot gases rotate in a toroidal shape. When the detonation altitude is low enough, these afterwinds will draw in dirt and debris from the ground below to form the stem of the mushroom cloud.

After the mass of hot gases reaches its equilibrium level, the ascent stops, the cloud starts flattening to the characteristic mushroom shape aided by surface growth due to the decaying turbulence. Nuclear detonations produced high above the ground might not create mushroom clouds with a stem; the heads of the clouds themselves consist of radioactive particles the fission products and other weapon debris aerosols, are dispersed by the wind, though weather patterns can produce problematic nuclear fallout. Detonations below ground level or deep below the water do not produce mushroom clouds, as the explosion causes the vaporization of a huge amount of earth and water in these instances, creating a bubble which collapses in on itself. Detonations underwater but near the surface produce a pillar of water, which, in collapsing, forms a cauliflower-like shape, mistaken for a mushroom cloud. Underground detonations at low depth produce a mushroom cloud and a base surge, two different distinct clouds.

The amount of radiation vented into the atmosphere decreases with increasing detonation depth. With s

The 2013–14 Liga Nacional de Ascenso de Honduras season was the 35th edition of the Honduran Liga Nacional de Ascenso, the second division of football in Honduras. Since last season, promotion was changed from a two-legged home-and-away match to a one-legged match in a neutral ground; the tournament began on 11 August 2013. Arsenal CD Honduras Social Sol Sula Trujillo FC Unión Sabá Yoro FC Atletico Choloma Atletico Limeño Atlético Nacional Atlético Municipal Graciano San Francisco Lepaera San Isidro Olimpia Occidental Real Juventud Villanueva FC Atlético Esperanzano Atlético Independiente Cobán Athletic Comayagua FC Marcala FC UPN Alianza de Becerra Atlético Olanchano Juticalpa F. C. Leon Libertador Valencia Valle FC

Roy Markham FRS was a British plant virologist who served as the fifth director of the John Innes Centre from 1967 until his death in 1979. Markham was born in London in 1916, his family relocated to Bridge of Allan in Scotland while he was young and returned to London in 1925. He attended several schools in England and in Magdeburg, but he disliked all of these until he started at St Paul's School in London, aged 15. During his years at St Paul's, he enjoyed his annual summer holidays at his family's house in Ventnor on the Isle of Wight, it was there that he met Margaret Mullen, whom he married. He joined Christ's College, Cambridge in 1935, specialising in biochemistry for the second part of his degree, he graduated in 1938 with an upper second class degree and became a PhD student in the laboratory of Norman Pirie, with whom he had worked as an undergraduate. For his thesis, which he completed in 1944, he worked on the isolation of plant viruses, including tomato bushy stunt virus and tobacco mosaic virus.

Markham continued working in Cambridge following his PhD, joining the Molteno Institute to work on the biochemistry of RNAs. One of his contemporaries at Cambridge was James Watson, who in his book, The Double Helix, recalls seeking TMV for an experiment: I thus went to Roy Markham to see if any spare TMV was on hand. Markham worked in the Molteno Institute, which unlike all other Cambridge labs, was well heated; this unusual state came from the asthma of David Keilin the Quick Professor and Director of the Molteno. I always welcomed an excuse to exist momentarily at 70 °F though I was never sure when Markham would start the conversation by saying how bad I looked, implying that if I had been brought up on English beer I would not be in my sorry state; this time he without hesitation volunteered some virus. The idea of Francis and me dirtying our hands with experiments brought unconcealed amusement, he returned to work on the structure of plant viruses at the end of the 1950s. He was interested in using electron microscopy to look at virus architecture.

In 1960, Markham became director of the Agricultural Research Council Virus Research Unit in Cambridge, succeeding Kenneth Smith. The research station was first opened in 1927 and became a research unit of the ARC in 1948; the John Innes Institute moved from Bayfordbury, Hertfordshire to Norwich, Norfolk in 1967, following its association with the newly-formed University of East Anglia. Before the institute's move was completed, its director, Kenneth S Doods, resigned to take up a position with the Food and Agriculture Organization in Turkey. Roy Markham was appointed as his successor, he, along with the Virus Research Unit, moved to Norwich in October 1967. Markham played an important role in establishing the institute at its new location, its move from Bayfordbury had led the majority of the institute's staff to find employment elsewhere, only 17 staff members moved to Norwich in 1967. However, under Markham's directorship, the institute grew and was reorganised into four new departments: Cell Biology, Applied Genetics and Ultrastructural Studies.

Markham persuaded the trustees of the John Innes Foundation, which owned the land on which the institute was built, to provide a large lecture hall and recreational facilities, including a swimming pool, for the staff. He took great interest in developing much of the technology at the new institute and listed himself under the'Electronics Section' in the institute's annual reports. Roy Markham suffered a heart attack from which he recovered. However, he developed bowel cancer and died on 16 November 1979