Toss bombing (sometimes known as loft bombing , and by the U.S. Air Force as the Low Altitude Bombing System , or LABS ) is a method of bombing where the attacking aircraft pulls upward when releasing its bomb load, giving the bomb additional time of flight by starting its ballistic path with an upward vector.
97-409: The purpose of toss bombing is to compensate for the gravity drop of the bomb in flight, and allow an aircraft to bomb a target without flying directly over it. This is to avoid overflying a heavily defended target, or to distance the attacking aircraft from the blast effects of a nuclear (or conventional) bomb. In pop-up bombing, the pilot approaches from low altitude in level flight, and on cues from
194-481: A cluster bomb or "cookie-cutter" configuration. It has been reported that during the height of the Cold War in the 1970s Moscow was targeted by up to 60 warheads. The reason that the cluster bomb concept is preferable in the targeting of cities is twofold: the first is that large singular warheads are much easier to neutralize as both tracking and successful interception by anti-ballistic missile systems than it
291-399: A 1 kt bomb is 0.22 km; for 100 kt, 1 km; and for 10 Mt, 4.7 km. Two distinct, simultaneous phenomena are associated with the blast wave in the air: Most of the material damage caused by a nuclear air burst is caused by a combination of the high static overpressures and the blast winds. The long compression of the blast wave weakens structures, which are then torn apart by
388-482: A brighter color, such as asphalt. If such a weather phenomenon as fog or haze is present at the point of the nuclear explosion, it scatters the flash , with radiant energy then reaching burn-sensitive substances from all directions. Under these conditions, opaque objects are therefore less effective than they would otherwise be without scattering, as they demonstrate maximum shadowing effect in an environment of perfect visibility and therefore zero scatterings. Similar to
485-415: A certain reflection angle, the reflected wave and the direct wave merge and form a reinforced horizontal wave, known as the '" Mach stem " and is a form of constructive interference . This phenomenon is responsible for the bumps or 'knees' in the above overpressure range graph. For each goal overpressure, there is a certain optimum burst height at which the blast range is maximized over ground targets. In
582-483: A climb, and the computer controls the actual release of the bomb. The integration into the FCC simplifies the pilot's workload by allowing the same bombing mode (CCRP) to be used for level, dive and loft bombing, providing similar cues in the pilot's displays regardless of the tactics used, since the computer simply sees it as the release point getting closer. Effects of nuclear explosions#Blast damage The effects of
679-432: A foggy or overcast day, although there are few if any, shadows produced by the sun on such a day, the solar energy that reaches the ground from the sun's infrared rays is nevertheless considerably diminished, due to it being absorbed by the water of the clouds and the energy also being scattered back into space. Analogously, so too is the intensity at a range of burning flash energy attenuated, in units of J /cm , along with
776-472: A high arc before falling on a target which was a considerable distance from its point of release. In the meantime, the maneuver had allowed the bomber to change direction and distance itself from the target. Author and retired USAF F-84 pilot Richard Bach describes such an attack in his book Stranger to the Ground : The last red-roofed village flashes below me, and the target, a pyramid of white barrels,
873-407: A large amount of radioactive material is released into the environment. This form of radioactive contamination is known as nuclear fallout and poses the primary risk of exposure to ionizing radiation for a large nuclear weapon. Details of nuclear weapon design also affect neutron emission: the gun-type assembly Little Boy leaked far more neutrons than the implosion-type 21 kt Fat Man because
970-401: A large area of Nagasaki , no true firestorm occurred in the city even though a higher yielding weapon was used. Many factors explain this seeming contradiction, including a different time of bombing than Hiroshima, terrain, and crucially, a lower fuel loading/fuel density than that of Hiroshima. Nagasaki probably did not furnish sufficient fuel for the development of a firestorm as compared to
1067-511: A larger bomb than would be necessary for a direct hit, in order to generate a larger blast that would destroy the target even if the bomb did not hit accurately due to windage or computer/pilot error. Laser-targeting (and other methods like GPS as used in the JDAM system) allows the bomb to correct minor deviations from the intended ballistic path after it has been released, making toss-bombing as accurate as level bombing while still providing most of
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#17327804238171164-460: A localized earthquake event is more probable. The first and fastest wave, equivalent to a normal earthquake's P wave , can inform the location of the test; the S wave and the Rayleigh wave follow. These can all be measured in most circumstances by seismic stations across the globe, and comparisons with actual earthquakes can be used to help determine estimated yield via differential analysis, by
1261-441: A method to attack heavily defended targets without unduly endangering the attacking aircraft. Although toss bombing might seem the direct opposite to dive bombing , where the plane pitches downward to aim at its target, toss bombing is often performed with a short dive before the bomber raises its nose and releases its bomb. This variant is known as "dive tossing". This gives both the bomb and aircraft extra momentum , thereby helping
1358-493: A moderate rain storm during an Operation Castle nuclear explosion were found to dampen, or reduce, peak pressure levels by approximately 15% at all ranges. Much of the destruction caused by a nuclear explosion is from blast effects. Most buildings, except reinforced or blast-resistant structures, will suffer moderate damage when subjected to overpressures of only 35.5 kilopascals (kPa) (5.15 pounds-force per square inch or 0.35 atm). Data obtained from Japanese surveys following
1455-463: A nuclear detonation . Eventually the shock wave dissipates to the point where the light becomes visible again giving rise to the characteristic double flash caused by the shock wave–fireball interaction. It is this unique feature of nuclear explosions that is exploited when verifying that an atmospheric nuclear explosion has occurred and not simply a large conventional explosion, with radiometer instruments known as Bhangmeters capable of determining
1552-505: A nuclear explosion on its immediate vicinity are typically much more destructive and multifaceted than those caused by conventional explosives . In most cases, the energy released from a nuclear weapon detonated within the lower atmosphere can be approximately divided into four basic categories: Depending on the design of the weapon and the location in which it is detonated, the energy distributed to any one of these categories may be significantly higher or lower. The physical blast effect
1649-496: A part of the Low Altitude Bombing System) that enables the pilot to release the bomb at the correct angle. The Toss Bomb Computer takes airspeed inputs from the aircraft's pitot system, altitude inputs from the static system, attitude inputs from the gyroscopic system and inputs from weapons selectors signifying the type of bomb to calculate the appropriate release point of the ordnance. Instead of triggering
1746-547: A point of comparison in the chart below, the most likely nuclear weapons to be used against countervalue city targets in a global nuclear war are in the sub-megaton range. Weapons of yields from 100 to 475 kilotons have become the most numerous in the US and Russian nuclear arsenals; for example, the warheads equipping the Russian Bulava submarine-launched ballistic missile ( SLBM ) have a yield of 150 kilotons. US examples are
1843-399: A result, the initial radiation becomes less of a hazard with increasing yield. With larger weapons, above 50 kt (200 TJ), blast and thermal effects are so much greater in importance that prompt radiation effects can be ignored. The neutron radiation serves to transmute the surrounding matter, often rendering it radioactive . When added to the dust of radioactive material released by the bomb,
1940-475: A target by pointing his aircraft directly at it. For a target on the ground, this means entering a dive. Thus designated, the pilot can then begin a climb, lofting the bomb at the target from a distance and regaining lost altitude at the same time. Due to the intense pilot workload involved with flying and entering the window of opportunity, some aircraft are equipped with a “Toss Bomb Computer” (in US nuclear delivery,
2037-487: A total dose of one gray , "lethal" to ten grays. This is only a rough estimate since biological conditions are neglected here. Further complicating matters, under global nuclear war scenarios with conditions similar to that during the Cold War , major strategically important cities like Moscow and Washington are likely to be hit numerous times from sub-megaton multiple independently targetable re-entry vehicles , in
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#17327804238172134-420: A typical air burst, where the blast range is maximized to produce the greatest range of severe damage, i.e. the greatest range that ~10 psi (69 kPa) of pressure is extended over, is a GR/ground range of 0.4 km for 1 kiloton (kt) of TNT yield; 1.9 km for 100 kt; and 8.6 km for 10 megatons (Mt) of TNT. The optimum height of burst to maximize this desired severe ground range destruction for
2231-403: Is caused by the initial brilliant flash of light produced by the nuclear detonation. More light energy is received on the retina than can be tolerated but less than is required for irreversible injury. The retina is particularly susceptible to visible and short wavelength infrared light since this part of the electromagnetic spectrum is focused by the lens on the retina. The result is bleaching of
2328-430: Is close enough to the nuclear fireball to be drawn into it, and is thus heated to the necessary temperatures to do so; this is known as trinitite . At the explosion of nuclear bombs lightning discharges sometimes occur. Smoke trails are often seen in photographs of nuclear explosions. These are not from the explosion; they are left by sounding rockets launched just prior to detonation. These trails allow observation of
2425-441: Is common for long-range early warning radars . The effect is less for higher frequencies in the microwave region, as well as lasting a shorter time – the effect falls off both in strength and the affected frequencies as the fireball cools and the electrons begin to re-form onto free nuclei. A second blackout effect is caused by the emission of beta particles from the fission products . These can travel long distances, following
2522-433: Is created by the coupling of immense amounts of energy, spanning the electromagnetic spectrum , with the surroundings. The environment of the explosion (e.g. submarine, ground burst , air burst , or exo-atmospheric) determines how much energy is distributed to the blast and how much to radiation. In general, surrounding a bomb with denser media, such as water, absorbs more energy and creates more powerful shock waves while at
2619-450: Is entirely different from the gamma-ray induced pulse produced by Compton electrons. The heat of the explosion causes air in the vicinity to become ionized, creating the fireball. The free electrons in the fireball affect radio waves, especially at lower frequencies. This causes a large area of the sky to become opaque to radar, especially those operating in the VHF and UHF frequencies, which
2716-419: Is from kinetic energy. For an explosion in the atmosphere, the fireball quickly expands to maximum size and then begins to cool as it rises like a balloon through buoyancy in the surrounding air. As it does so, it takes on the flow pattern of a vortex ring with incandescent material in the vortex core as seen in certain photographs. This effect is known as a mushroom cloud . Sand will fuse into glass if it
2813-491: Is generally to the contrary to what other less technical sources state. The "oily" black soot particles, are a characteristic of incomplete combustion in the city firestorm. The element einsteinium was discovered when analyzing nuclear fallout. A side-effect of the Pascal-B nuclear test during Operation Plumbbob may have resulted in the first man-made object launched into space. The so-called "thunder well" effect from
2910-418: Is generally used at moderate altitude (to allow for the dive) when the target, for whatever reason, cannot be designated precisely by radar. A target for instance may present too small a signature to be visible on radar (such as the entrance to an underground bunker) or may be indistinguishable in a group of radar returns. The pilot can in this case use a special "boresight" mode that allows the pilot to designate
3007-413: Is highly likely and radiation poisoning is almost certain if one is caught in the open with no terrain or building masking effects within a radius of 0–3 kilometres (0.0–1.9 mi) from a 1 megaton airburst, and the 50% chance of death from the blast extends out to ~8 kilometres (5.0 mi) from the same 1 megaton atmospheric explosion. An example that highlights the variability in the real world and
Toss bombing - Misplaced Pages Continue
3104-437: Is just visible at the end of its run-in line. Five hundred knots. Switch down, button pressed. Timers begin their timing, circuits are alerted for the drop. Inch down to treetop altitude. I do not often fly at 500 knots on the deck, and it is apparent that I am moving quickly. The barrels inflate. I see that their white paint is flaking. And the pyramid streaks beneath me. Back on the stick smoothly firmly to read four G on
3201-477: Is not the case with thermionic tubes (or valves) which are relatively immune to EMP. A Faraday cage does not offer protection from the effects of EMP unless the mesh is designed to have holes no bigger than the smallest wavelength emitted from a nuclear explosion. Large nuclear weapons detonated at high altitudes also cause geomagnetically induced current in very long electrical conductors. The mechanism by which these geomagnetically induced currents are generated
3298-417: Is often associated with a mushroom cloud . In a high-altitude burst where the density of the atmosphere is low, more energy is released as ionizing gamma radiation and X-rays than as an atmosphere-displacing shockwave. The high temperatures and radiation cause gas to move outward radially in a thin, dense shell called "the hydrodynamic front". The front acts like a piston that pushes against and compresses
3395-410: Is responsible for warming the atmospheric nitrogen close to the bomb and causing the creation of atmospheric NOx smog components. This, as part of the mushroom cloud , is shot into the stratosphere where it is responsible for dissociating ozone there , in the same way combustion NOx compounds do. The amount created depends on the yield of the explosion and the blast's environment. Studies done on
3492-404: Is that this tactic along with limiting the risk of failure reduces individual bomb yields, and therefore reduces the possibility of any serious collateral damage to non-targeted nearby civilian areas, including that of neighboring countries. This concept was pioneered by Philip J. Dolan and others. Gamma rays from the nuclear processes preceding the true explosion may be partially responsible for
3589-464: Is when several smaller incoming warheads are approaching. This strength in numbers advantage to lower yield warheads is further compounded by such warheads tending to move at higher incoming speeds, due to their smaller, more slender physics package size, assuming both nuclear weapon designs are the same (a design exception being the advanced W88 ). The second reason for this cluster bomb, or 'layering' (using repeated hits by accurate low yield weapons)
3686-577: The W76 and W88 warheads, with the lower yield W76 being over twice as numerous as the W88 in the US nuclear arsenal. For the direct radiation effects the slant range instead of the ground range is shown here because some effects are not given even at ground zero for some burst heights. If the effect occurs at ground zero the ground range can be derived from slant range and burst altitude ( Pythagorean theorem ). "Acute radiation syndrome" corresponds here to
3783-467: The abdominal cavity , which contain air, are particularly injured. The damage causes severe hemorrhaging or air embolisms , either of which can be rapidly fatal. The overpressure estimated to damage lungs is about 70 kPa. Some eardrums would probably rupture around 22 kPa (0.2 atm) and half would rupture between 90 and 130 kPa (0.9 to 1.2 atm). Nuclear weapons emit large amounts of thermal radiation as visible, infrared, and ultraviolet light, to which
3880-416: The atomic bombings of Hiroshima and Nagasaki found that 8 psi (55 kPa) was sufficient to destroy all wooden and brick residential structures. This can reasonably be defined as the pressure capable of producing severe damage. The blast wind at sea level may exceed 1,000 km/h, or ~300 m/s, approaching the speed of sound in air. The range for blast effects increases with the explosive yield of
3977-428: The ionosphere . Electronics can be shielded by wrapping them completely in conductive material such as metal foil; the effectiveness of the shielding may be less than perfect. Proper shielding is a complex subject due to the large number of variables involved. Semiconductors , especially integrated circuits , are extremely susceptible to the effects of EMP due to the close proximity of their p–n junctions , but this
Toss bombing - Misplaced Pages Continue
4074-500: The vertical so it is tossed back toward the target. This tactic was first made public on 7 May 1957 at Eglin AFB , when a B-47 entered its bombing run at low altitude, pulled up sharply (3.5 g ) into a half loop , releasing its bomb under automatic control at a predetermined point in its climb, then executed a half roll, completing a maneuver similar to an Immelmann turn or Half Cuban Eight . The bomb continued upward for some time in
4171-643: The Earth's magnetic field lines. When they reach the upper atmosphere they cause ionization similar to the fireball but over a wider area. Calculations demonstrate that one megaton of fission, typical of a two-megaton H-bomb, will create enough beta radiation to blackout an area 400 kilometres (250 miles) across for five minutes. Careful selection of the burst altitudes and locations can produce an extremely effective radar-blanking effect. The physical effects giving rise to blackouts also cause EMP, which can also cause power blackouts. The two effects are otherwise unrelated, and
4268-528: The Earth's magnetic field to produce a coherent nuclear electromagnetic pulse (NEMP) which lasts about one millisecond. Secondary effects may last for more than a second. The pulse is powerful enough to cause moderately long metal objects (such as cables) to act as antennas and generate high voltages due to interactions with the electromagnetic pulse. These voltages can destroy unshielded electronics. There are no known biological effects of EMP. The ionized air also disrupts radio traffic that would normally bounce off
4365-613: The accelerometer and center the needles of the indicator that is only used in nuke weapon drops and center them and hold it there and I'll bet those computers are grinding their little hearts out and all I can see is sky in the windscreen hold the G's keep the needles centered there's the sun going beneath me and WHAM. My airplane rolls hard to the right and tucks more tightly into her loop and strains ahead even though we are upside down. The Shape has released me more than I have released it. The little white barrels are now six thousand feet directly beneath my canopy. I have no way to tell if it
4462-431: The advantages of toss-bombing using unguided munitions. However, the targeting pods used to deliver guided munitions generally have a limit to their field of view; most specifically, the pod usually cannot look behind the aircraft at more than a certain angle. Lofting the bomb allows the pilot to keep the target in front of the aircraft and thus within the targeting pod's field of view for as long as possible. "Dive-tossing"
4559-454: The aircraft regain altitude after the release, and also ensuring that airspeed at the calculated release point is still sufficient to get the bomb to the target. A more dynamic variant of toss bombing, called over-the-shoulder bombing , or the LABS (Low Altitude Bombing System) maneuver (known to pilots as the "idiot's loop"), is a particular kind of loft bombing where the bomb is released past
4656-411: The aircraft to short-range defenses surrounding the target, but will place the aircraft in the bomb's blast radius. By executing a "pop-up" loft, on the other hand, the pilot releases the munition well outside the target area, out of range of air defenses. After release, the pilot can either dive back to low altitude or maintain the climb, in either case generally executing a sharp turn or "slice" away from
4753-479: The atmosphere is largely transparent. This is known as "flash". The chief hazards are burns and eye injuries. On clear days, these injuries can occur well beyond blast ranges, depending on weapon yield. Fires may also be started by the initial thermal radiation, but the following high winds due to the blast wave may put out almost all such fires, unless the yield is very high where the range of thermal effects vastly outranges blast effects, as observed from explosions in
4850-537: The blast wave effects such as from upset stoves and furnaces. In Hiroshima on 6 August 1945, a tremendous firestorm developed within 20 minutes after detonation and destroyed many more buildings and homes, built out of predominantly 'flimsy' wooden materials. A firestorm has gale-force winds blowing in towards the center of the fire from all directions. It is not peculiar to nuclear explosions, having been observed frequently in large forest fires and following incendiary raids during World War II. Despite fires destroying
4947-399: The blast winds. The compression, vacuum and drag phases together may last several seconds or longer, and exert forces many times greater than the strongest hurricane . Acting on the human body, the shock waves cause pressure waves through the tissues. These waves mostly damage junctions between tissues of different densities (bone and muscle) or the interface between tissue and air. Lungs and
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#17327804238175044-477: The blast's normally invisible shock wave in the moments following the explosion. The heat and airborne debris created by a nuclear explosion can cause rain; the debris is thought to do this by acting as cloud condensation nuclei . During the city firestorm which followed the Hiroshima explosion, drops of water were recorded to have been about the size of marbles . This was termed black rain and has served as
5141-461: The bomb case. Building a bomb case of materials which transmitted rather than absorbed the neutrons could make the bomb more intensely lethal to humans from prompt neutron radiation. This is one of the features used in the development of the neutron bomb . The seismic pressure waves created from an explosion may release energy within nearby plates or otherwise cause an earthquake event. An underground explosion concentrates this pressure wave, and
5238-635: The burning of combustible material. Fire experts suggest that unlike Hiroshima, due to the nature of modern U.S. city design and construction, a firestorm in modern times is unlikely after a nuclear detonation. This does not exclude fires from being started but means that these fires will not form into a firestorm, due largely to the differences between modern building materials and those used in World War II-era Hiroshima. There are two types of eye injuries from thermal radiation: flash blindness and retinal burn . Flash blindness
5335-417: The computer pulls up at the last moment to release the bomb. Release usually occurs between 20° and 75° above the horizontal, causing the bomb to be tossed upward and forward, much like an underarm throw of a ball. Although "pop-up" bombing is generally characterized by its low-level approach, the same technique of a toss starting from level flight can be used at any altitude when it is not desirable to overfly
5432-410: The corresponding free electrons. The system then immediately emits electromagnetic (thermal) radiation, the nature of which is determined by the temperature. Since this is of the order of 10 degrees, most of the energy emitted within a microsecond or so is in the soft X-ray region. Because temperature depends on the average internal energy/heat of the particles in a certain volume, internal energy or heat
5529-414: The damage to modern urban areas has found that most scaling laws are too simplistic and tend to overestimate nuclear explosion effects. The scaling laws that were used to produce the table below assume (among other things) a perfectly level target area, no attenuating effects from urban terrain masking (e.g. skyscraper shadowing), and no enhancement effects from reflections and tunneling by city streets. As
5626-455: The effect of being indoors is Akiko Takakura. Despite the lethal radiation and blast zone extending well past her position at Hiroshima, Takakura survived the effects of a 16 kt atomic bomb at a distance of 300 metres (980 ft) from the hypocenter, with only minor injuries, due mainly to her position in the lobby of the Bank of Japan, a reinforced concrete building, at the time. In contrast,
5723-404: The electrons are removed entirely from the atoms, thus causing ionization. Others are raised to higher energy (or excited) states while still remaining attached to the nuclei. Within an extremely short time, perhaps a hundredth of a microsecond or so, the weapon residues consist essentially of completely and partially stripped (ionized) atoms, many of the latter being in excited states, together with
5820-436: The energy produced by a nuclear explosion is usually millions of times more powerful per unit mass, and temperatures may briefly reach the tens of millions of degrees. Energy from a nuclear explosion is initially released in several forms of penetrating radiation. When there is surrounding material such as air, rock, or water, this radiation interacts with and rapidly heats the material to an equilibrium temperature (i.e. so that
5917-535: The energy released in the explosion, depending on the yield of the device. In urban areas, the extinguishing of fires ignited by thermal radiation may matter little, as in a surprise attack fires may also be started by blast-effect-induced electrical shorts, gas pilot lights, overturned stoves, and other ignition sources, as was the case in the breakfast-time bombing of Hiroshima. Whether or not these secondary fires will in turn be snuffed out as modern noncombustible brick and concrete buildings collapse in on themselves from
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#17327804238176014-417: The explosion. The height of burst and apparent size of the fireball, a function of yield and range will determine the degree and extent of retinal scarring. A scar in the central visual field would be more debilitating. Generally, a limited visual field defect, which will be barely noticeable, is all that is likely to occur. When thermal radiation strikes an object, part will be reflected, part transmitted, and
6111-408: The following fireball, as they may superheat nearby air and/or other material. The vast majority of the energy that goes on to form the fireball is in the soft X-ray region of the electromagnetic spectrum, with these X-rays being produced by the inelastic collisions of the high-speed fission and fusion products. It is these reaction products and not the gamma rays which contain most of the energy of
6208-451: The group is exposed to 60 to 180 rems, 50% will become sick with radiation poisoning . If medically treated, all of the 60–180 rems group will survive. If the group is exposed to 200 to 450 rems, most if not all of the group will become sick; 50% will die within two to four weeks, even with medical attention. If the group is exposed to 460 to 600 rems, 100% of the group will get radiation poisoning, and 50% will die within one to three weeks. If
6305-472: The group is exposed to 600 to 1000 rems, 50% will die in one to three weeks. If the group is exposed to 1,000 to 5,000 rems, 100% of the group will die within 2 weeks. At 5,000 rems, 100% of the group will die within 2 days. Researchers from the University of Nicosia simulated, using high-order computational fluid dynamics , an atomic bomb explosion from a typical intercontinental ballistic missile and
6402-438: The initial gamma radiation includes that arising from these reactions as well as that resulting from the decay of short-lived fission products. The intensity of initial nuclear radiation decreases rapidly with distance from the point of burst because the radiation spreads over a larger area as it travels away from the explosion (the inverse-square law ). It is also reduced by atmospheric absorption and scattering. The character of
6499-431: The light hydrogen nuclei (protons) predominating in the exploded TNT molecules (surrounding the core of Fat Man) slowed down neutrons very efficiently while the heavier iron atoms in the steel nose forging of Little Boy scattered neutrons without absorbing much neutron energy. It was found in early experimentation that normally most of the neutrons released in the cascading chain reaction of the fission bomb are absorbed by
6596-429: The many buildings on the flat terrain at Hiroshima. As thermal radiation travels more or less in a straight line from the fireball (unless scattered), any opaque object will produce a protective shadow that provides protection from the flash burn. Depending on the properties of the underlying surface material, the exposed area outside the protective shadow will be either burnt to a darker color, such as charring wood, or
6693-437: The material is a poor thermal conductor, the heat is confined to the surface of the material. The actual ignition of materials depends on how long the thermal pulse lasts and the thickness and moisture content of the target. Near ground zero where the energy flux exceeds 125 J /cm , what can burn, will. Farther away, only the most easily ignited materials will flame. Incendiary effects are compounded by secondary fires started by
6790-417: The matter is at the same temperature as the fuel powering the explosion). This causes vaporization of the surrounding material, resulting in its rapid expansion. Kinetic energy created by this expansion contributes to the formation of a shock wave which expands spherically from the center. Intense thermal radiation at the hypocenter forms a nuclear fireball which, if the explosion is low enough in altitude,
6887-573: The modelling of the high-frequency (>4 Hz) teleseismic P wave amplitudes. However, theory does not suggest that a nuclear explosion of current yields could trigger fault rupture and cause a major quake at distances beyond a few tens of kilometers from the shot point. The following table summarizes the most important effects of single nuclear explosions under ideal, clear skies, weather conditions. Tables like these are calculated from nuclear weapons effects scaling laws. Advanced computer modelling of real-world conditions and how they impact on
6984-418: The multi-megaton range. This is because the intensity of the blast effects drops off with the third power of distance from the explosion, while the intensity of radiation effects drops off with the second power of distance. This results in the range of thermal effects increasing markedly more than blast range as higher and higher device yields are detonated. Thermal radiation accounts for between 35 and 45% of
7081-523: The nature of explosions. For air bursts at or near sea level, 50–60% of the explosion's energy goes into the blast wave , depending on the size and the yield of the bomb . As a general rule, the blast fraction is higher for low yield weapons. Furthermore, it decreases at high altitudes because there is less air mass to absorb radiation energy and convert it into a blast. This effect is most important for altitudes above 30 km, corresponding to less than 1 percent of sea-level air density. The effects of
7178-419: The nuclear reactions in the form of kinetic energy. This kinetic energy of the fission and fusion fragments is converted into internal and then radiation energy by approximately following the process of blackbody radiation emitting in the soft X-ray region. As a result of numerous inelastic collisions, part of the kinetic energy of the fission fragments is converted into internal and radiation energy. Some of
7275-474: The radiation received at a given location also varies with the distance from the explosion. Near the point of the explosion, the neutron intensity is greater than the gamma intensity, but with increasing distance the neutron-gamma ratio decreases. Ultimately, the neutron component of the initial radiation becomes negligible in comparison with the gamma component. The range for significant levels of initial radiation does not increase markedly with weapon yield and, as
7372-431: The reaction until all the world's atmospheric nitrogen was consumed. Hans Bethe was assigned to study this hypothesis from the project's earliest days, and he eventually concluded that such a reaction could not sustain itself on a large scale due to cooling of the nuclear fireball through an inverse Compton effect. Richard Hamming was asked to make a similar calculation just before the first nuclear test , and he reached
7469-482: The release directly, the pilot instead "consents" to release the weapon, then begins a steady climb. The computer then calculates the desired ballistic path, and when that path will be produced by the current aircraft attitude and airspeed, the computer releases the bomb. During the Second World War the engineers Erik Wilkenson and Torsten Faxén at Saab developed the first bomb sight for toss bombing. It
7566-420: The rest absorbed. The fraction that is absorbed depends on the nature and color of the material. A thin material may transmit most of the radiation. A light-colored object may reflect much of the incident radiation and thus escape damage, like anti-flash white paint. The absorbed thermal radiation raises the temperature of the surface and results in scorching, charring, and burning of wood, paper, fabrics, etc. If
7663-506: The resulting blast wave to see how it would affect people sheltering indoors. They found that the blast wave was enough in the moderate damage zone to topple some buildings and injure people caught outdoors. However, sturdier buildings, such as concrete structures, can remain standing. The team used advanced computer modelling to study how a nuclear blast wave speeds through a standing structure. Their simulated structure featured rooms, windows, doorways, and corridors and allowed them to calculate
7760-408: The same blast wave is uncertain, not least of which, because of the masking effect of modern city landscapes on thermal and blast transmission are continually examined. When combustible frame buildings were blown down in Hiroshima and Nagasaki, they did not burn as rapidly as they would have done had they remained standing. The noncombustible debris produced by the blast frequently covered and prevented
7857-486: The same conclusion. Nevertheless, the notion has persisted as a rumor for many years and was the source of apocalyptic gallows humor at the Trinity test where Enrico Fermi took side bets on atmospheric ignition. Survivability is highly dependent on factors such as if one is indoors or out, the size of the explosion, the proximity to the explosion, and to a lesser degree the direction of the wind carrying fallout. Death
7954-415: The same time limiting the area of its effect. When a nuclear weapon is surrounded only by air, lethal blast and thermal effects proportionally scale much more rapidly than lethal radiation effects as explosive yield increases. This bubble is faster than the speed of sound . The physical damage mechanisms of a nuclear weapon (blast and thermal radiation) are identical to those of conventional explosives, but
8051-428: The similar naming can be confusing. About 5% of the energy released in a nuclear air burst is in the form of ionizing radiation : neutrons , gamma rays, alpha particles and electrons moving at speeds up to the speed of light. Gamma rays are high-energy electromagnetic radiation; the others are particles that move slower than light. The neutrons result almost exclusively from the fission and fusion reactions, while
8148-408: The slant/horizontal range of a nuclear explosion, during fog or haze conditions. So despite any object that casts a shadow being rendered ineffective as a shield from the flash by fog or haze, due to scattering, the fog fills the same protective role, but generally only at the ranges that survival in the open is just a matter of being protected from the explosion's flash energy. The thermal pulse also
8245-567: The source of a book and film by the same name . Black rain is not unusual following large fires and is commonly produced by pyrocumulus clouds during large forest fires. The rain directly over Hiroshima on that day is said to have begun around 9 a.m. with it covering a wide area from the hypocenter to the northwest, raining heavily for one hour or more in some areas. The rain directly over the city may have carried neutron activated building material combustion products, but it did not carry any appreciable nuclear weapon debris or fallout, although this
8342-418: The surrounding medium to make a spherically expanding shock wave . At first, this shock wave is inside the surface of the developing fireball, which is created in a volume of air heated by the explosion's "soft" X-rays. Within a fraction of a second, the dense shock front obscures the fireball and continues to move past it, expanding outwards and free from the fireball, causing a reduction of light emanating from
8439-459: The target. Additional altitude at release gives the bomb additional time of flight and range, at the cost (in the case of unguided munitions) of accuracy due to windage and the increased effect of a slight deviation in flight path. The Dive-toss delivery technique was the first "toss" bombing method developed after WWII at the US Navy's rocket development center at Inyokern, California in 1947 as
8536-407: The target. The blast produced by powerful munitions is thus (hopefully) avoided. The value of toss-bombing was increased with the introduction of precision-guided munitions such as the laser-guided bomb . Previous "dumb bombs" required a very high degree of pilot and fire control computer precision to loft the bomb accurately to the target. Unguided loft bombing also generally called for the use of
8633-453: The total effect of nuclear blasts on the ozone layer have been at least tentatively exonerating after initial discouraging findings. Gamma rays from a nuclear explosion produce high energy electrons through Compton scattering . For high altitude nuclear explosions, these electrons are captured in the Earth's magnetic field at altitudes between 20 and 40 kilometers where they interact with
8730-579: The underground explosion may have launched a metal cover plate into space at six times Earth's escape velocity , although the evidence remains subject to debate. In 1942, there was speculation among the scientists developing the first nuclear weapons in the Manhattan Project that a sufficiently large nuclear explosion might ignite the Earth's atmosphere: heat from the explosion might fuse pairs of atmospheric nitrogen atoms, forming carbon and oxygen while releasing further energy which would sustain
8827-519: The unknown person sitting outside, fully exposed, on the steps of the Sumitomo Bank , next door to the Bank of Japan, received lethal third-degree burns and was then likely killed by the blast, in that order, within two seconds. With medical attention, radiation exposure is survivable to 200 rems of acute dose exposure. If a group of people is exposed to a 50 to 59 rems acute (within 24 hours) radiation dose, none will get radiation sickness. If
8924-405: The use of limited-aspect targeting devices for guided munitions. To counter air defenses en route to the target, remaining at a low altitude for as long as possible allows the bomber to avoid radar and visual tracking and the launch envelope of older missile systems designed to be fired at targets overflying the missile site. However, a level pass at the target at low altitude will not only expose
9021-402: The visual pigments and temporary blindness for up to 40 minutes. A retinal burn resulting in permanent damage from scarring is also caused by the concentration of direct thermal energy on the retina by the lens. It will occur only when the fireball is actually in the individual's field of vision and would be a relatively uncommon injury. Retinal burns may be sustained at considerable distances from
9118-414: The weapon and also depends on the burst altitude. Contrary to what might be expected from geometry, the blast range is not maximal for surface or low altitude blasts but increases with altitude up to an "optimum burst altitude" and then decreases rapidly for higher altitudes. This is caused by the nonlinear behavior of shock waves. When the blast wave from an air burst reaches the ground it is reflected. Below
9215-627: Was a good drop or not. That was decided back with the charts and graphs and the dividers and the angles. I kept the needles centered, the computers did their task automatically, and the Device is on its way. Toss bombing is generally used by pilots whenever it is not desirable to overfly the target with the aircraft at an altitude sufficient for dive-bombing or level bombing. Such cases include heavy anti-air defenses such as AAA and SAMs , when deploying powerful weapons such as 2,000 lb (910 kg) "iron bombs" or even tactical nuclear bombs , and
9312-590: Was a mechanical computer that did the necessary calculations. It was first used in the Saab 17 and was standard on all Saab fighters up to and including Saab 32 Lansen . It was also sold to France, Switzerland, Denmark and USA and was used in for instance the Boeing B-47 Stratojet . While deployed in Europe with NATO , RCAF CF-104 fighter-bombers carried a Toss Bomb Computer until their nuclear role
9409-637: Was eliminated by the Canadian government effective 1 January 1972. The same computational solutions used in the LABS system are now incorporated into two of the major bombing modes (the computer-controlled CCRP and a dedicated visually oriented "Dive-Toss" mode) of the Fire Control Computer of modern strike fighters such as the F-15E and F-16 . As with LABS, the pilot designates their desired impact point, then consents to release while executing
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