Paintball is a competitive team shooting sport in which players eliminate opponents from play by hitting them with spherical dye-filled gelatin capsules that break upon impact. Paintballs are shot using a low-energy air weapon called a paintball marker, powered by compressed air or carbon dioxide and was designed for remotely marking trees and cattle; the game was developed in May 1981 for recreation, but now is played at a formal sporting level with organized competition that involves major tournaments, professional teams, players. Paintball technology is used by military forces, law enforcement and security organizations to supplement military or other training. Paintball markers can play nonlethal suppression of dangerous suspects. Games can be played on outdoor fields of varying sizes. A game field is scattered with artificial terrain, which players use for tactical cover. Game types and goals vary, but may include capture the flag, defending or attacking a particular point or area, or capturing objects of interest hidden in the playing area.
Depending on the variant played, games can last from minutes to hours, or days in "scenario play". The legality of paintball varies among regions. In most areas where regulated play is offered, players are required to wear protective masks, use barrel blocking safety equipment, safe game rules are enforced; the paintball equipment used may depend on the game type, for example: woodsball, speedball, or scenario. However every player will utilize three basic pieces of equipment: Paintball marker: known as a "paintball gun", this is the primary piece of equipment, used to mark the opposing player with paintballs; the paintball gun must have a loader or "hopper" or magazines attached to feed paint into the marker, will be either spring-fed, gravity-fed, or electronically force-fed. Modern markers require a compressed air CO2 tank. In contrast early bolt-action paintball markers used disposable silver capsules seen in pellet guns. In the mid to late 1980s, marker mechanics improved to include constant air pressure and semi-automatic operation.
Further improvements included increased rates of fire. The use of unstable CO2 causes damage to the low-pressure pneumatic components inside electronic markers, therefore the more stable compressed air is preferred by owners of such markers. Paintballs: Paintballs, the ammunition used in the marker, are spherical gelatin capsules containing polyethylene glycol, other non-toxic and water-soluble substances, dye; the quality of paintballs is dependent on the brittleness of the ball's shell, the roundness of the sphere, the thickness of the fill. The highest-grade paintballs incorporate cornstarch and metallic flake into the fill to leave a thick glittery "splat", obvious against any background color, hard to wipe off. All paintballs in use today are biodegradeable. All ingredients used in the making of a paintball are food-grade quality and are harmless to the participants and environment. Manufacturers and distributors have been making the effort to move away from the traditional oil-based paints and compressed CO2 gas propellant, to a more friendly water-based formula and compressed air in an effort to become more "eco-friendly".
Paintballs come including of 0.50 inches an 0.68 inches. Mask or goggles: Masks are safety devices players are required to wear at all times on the field, to protect them from paintballs; the original equipment used by players were safety goggles of the type used in labs and wood shops. Masks can feature throat guards. Modern masks have developed to be less bulky compared with older designs; some players may remove the mouth and/or ear protection for aesthetic or comfort reasons, but this is neither recommended nor allowed at commercial venues. Additional equipment seen among frequent players, tournament participants, professional players include: Pods and pod packs: The most common addition to the above "mandatory" equipment, pods are plastic containers with flip-open lids, that store paintballs in a ready-to-use manner. Pods are available in many sizes, including 10, 80, 100 and 140-round sizes, with the larger 140-round pods being most common among tournament players. Pods are carried by the player in pod packs or harnesses which facilitate easy access to the pods during play.
There are several designs of pod packs, from belt loops allowing a recreational player to carry one or two extra pods, to harness designs designed for either tournament-style or scenario-style players. Squeegee/swab – From time to time, a paintball will break inside the player's marker; when this happens it coats the inner surfaces of the marker with paint the barrel, which reduces accuracy. While speedball and tournament players have no time to clear this obstruction and instead "shoot thro
Atmosphere of Earth
The atmosphere of Earth is the layer of gases known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention, reducing temperature extremes between day and night. By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, small amounts of other gases. Air contains a variable amount of water vapor, on average around 1% at sea level, 0.4% over the entire atmosphere. Air content and atmospheric pressure vary at different layers, air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in Earth's troposphere and in artificial atmospheres; the atmosphere has a mass of about 5.15×1018 kg, three quarters of, within about 11 km of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space.
The Kármán line, at 100 km, or 1.57% of Earth's radius, is used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km. Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition; the study of Earth's atmosphere and its processes is called atmospheric science. Early pioneers in the field include Richard Assmann; the three major constituents of Earth's atmosphere are nitrogen and argon. Water vapor accounts for 0.25% of the atmosphere by mass. The concentration of water vapor varies from around 10 ppm by volume in the coldest portions of the atmosphere to as much as 5% by volume in hot, humid air masses, concentrations of other atmospheric gases are quoted in terms of dry air; the remaining gases are referred to as trace gases, among which are the greenhouse gases, principally carbon dioxide, nitrous oxide, ozone. Filtered air includes trace amounts of many other chemical compounds.
Many substances of natural origin may be present in locally and seasonally variable small amounts as aerosols in an unfiltered air sample, including dust of mineral and organic composition and spores, sea spray, volcanic ash. Various industrial pollutants may be present as gases or aerosols, such as chlorine, fluorine compounds and elemental mercury vapor. Sulfur compounds such as hydrogen sulfide and sulfur dioxide may be derived from natural sources or from industrial air pollution; the relative concentration of gases remains constant until about 10,000 m. In general, air pressure and density decrease with altitude in the atmosphere. However, temperature has a more complicated profile with altitude, may remain constant or increase with altitude in some regions; because the general pattern of the temperature/altitude profile is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. In this way, Earth's atmosphere can be divided into five main layers.
Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere and thermosphere. From highest to lowest, the five main layers are: Exosphere: 700 to 10,000 km Thermosphere: 80 to 700 km Mesosphere: 50 to 80 km Stratosphere: 12 to 50 km Troposphere: 0 to 12 km The exosphere is the outermost layer of Earth's atmosphere, it extends from the exobase, located at the top of the thermosphere at an altitude of about 700 km above sea level, to about 10,000 km where it merges into the solar wind. This layer is composed of low densities of hydrogen and several heavier molecules including nitrogen and carbon dioxide closer to the exobase; the atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another. Thus, the exosphere no longer behaves like a gas, the particles escape into space; these free-moving particles follow ballistic trajectories and may migrate in and out of the magnetosphere or the solar wind. The exosphere is located too far above Earth for any meteorological phenomena to be possible.
However, the aurora borealis and aurora australis sometimes occur in the lower part of the exosphere, where they overlap into the thermosphere. The exosphere contains most of the satellites orbiting Earth; the thermosphere is the second-highest layer of Earth's atmosphere. It extends from the mesopause at an altitude of about 80 km up to the thermopause at an altitude range of 500–1000 km; the height of the thermopause varies due to changes in solar activity. Because the thermopause lies at the lower boundary of the exosphere, it is referred to as the exobase; the lower part of the thermosphere, from 80 to 550 kilometres above Earth's surface, contains the ionosphere. The temperature of the thermosphere increases with height. Unlike the stratosphere beneath it, wherein a temperature inversion is due to the absorption of radiation by ozone, the inversion in the t
Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure. Various units are used to express pressure; some of these derive from a unit of force divided by a unit of area. Pressure may be expressed in terms of standard atmospheric pressure. Manometric units such as the centimetre of water, millimetre of mercury, inch of mercury are used to express pressures in terms of the height of column of a particular fluid in a manometer. Pressure is the amount of force applied at right angles to the surface of an object per unit area; the symbol for it is p or P. The IUPAC recommendation for pressure is a lower-case p. However, upper-case P is used; the usage of P vs p depends upon the field in which one is working, on the nearby presence of other symbols for quantities such as power and momentum, on writing style. Mathematically: p = F A, where: p is the pressure, F is the magnitude of the normal force, A is the area of the surface on contact.
Pressure is a scalar quantity. It relates the vector surface element with the normal force acting on it; the pressure is the scalar proportionality constant that relates the two normal vectors: d F n = − p d A = − p n d A. The minus sign comes from the fact that the force is considered towards the surface element, while the normal vector points outward; the equation has meaning in that, for any surface S in contact with the fluid, the total force exerted by the fluid on that surface is the surface integral over S of the right-hand side of the above equation. It is incorrect to say "the pressure is directed in such or such direction"; the pressure, as a scalar, has no direction. The force given by the previous relationship to the quantity has a direction, but the pressure does not. If we change the orientation of the surface element, the direction of the normal force changes accordingly, but the pressure remains the same. Pressure is distributed to solid boundaries or across arbitrary sections of fluid normal to these boundaries or sections at every point.
It is a fundamental parameter in thermodynamics, it is conjugate to volume. The SI unit for pressure is the pascal, equal to one newton per square metre; this name for the unit was added in 1971. Other units of pressure, such as pounds per square inch and bar, are in common use; the CGS unit of pressure is 0.1 Pa.. Pressure is sometimes expressed in grams-force or kilograms-force per square centimetre and the like without properly identifying the force units, but using the names kilogram, kilogram-force, or gram-force as units of force is expressly forbidden in SI. The technical atmosphere is 1 kgf/cm2. Since a system under pressure has the potential to perform work on its surroundings, pressure is a measure of potential energy stored per unit volume, it is therefore related to energy density and may be expressed in units such as joules per cubic metre. Mathematically: p =; some meteorologists prefer the hectopascal for atmospheric air pressure, equivalent to the older unit millibar. Similar pressures are given in kilopascals in most other fields, where the hecto- prefix is used.
The inch of mercury is still used in the United States. Oceanographers measure underwater pressure in decibars because pressure in the ocean increases by one decibar per metre depth; the standard atmosphere is an established constant. It is equal to typical air pressure at Earth mean sea level and is defined as 101325 Pa; because pressure is measured by its ability to displace a column of liquid in a manometer, pressures are expressed as a depth of a particular fluid. The most common choices are water; the pressure exerted by a column of liquid of height h and density ρ is given by the hydrostatic pressure equation p = ρgh, where g is the gravitational acceleration. Fluid density and local gravity can vary from one reading to another depending on local factors, so the height of a fluid column
Paintball is an equipment intensive sport and in order to safely conduct a game, every player requires a marker with propellant to fire the paint, a mask to protect the eyes and face, a loader to hold them. To ensure safety off the playing field, a barrel sock or plug for the marker is compulsory. Depending on type of play, additional equipment can include gloves, a pack designed to comfortably carry pods containing extra paintballs, a squeegee or swab for cleaning out the barrel in case a paintball breaks. Players may elect to wear padding or armor in order to reduce the impact of incoming paintballs. A paintball marker is the primary piece of equipment used in paintball to tag an opposing player. An expanding gas forces a paintball through the barrel at a muzzle velocity of 90 m/s; this velocity is sufficient for most paintballs to break upon impact at a distance, but not so fast as to cause tissue damage beyond mild bruising. Nearly every commercial field has, enforces, a rule limiting the muzzle velocity of a paintball at or below 90 m/s.
Speeds above 250 are needed to ensure the paintball breaks on impact. The technology used to design and build paintball markers has advanced over time, beginning with the original "Nel-Spot" bolt-action pistols, progressing to pump-action markers to semi-automatic mechanical markers, culminating in the electropneumatic paintball marker. In mechanical designs, the trigger manipulates a sear, holding a hammer, ram, or sealed gas chamber in its resting state. Pulling the trigger releases the sear, allowing the marker's action to cycle. There are a variety of mechanical designs, the most common being the "blow-back" marker, which utilizes a spring-loaded ram released by the sear to open a pin valve. There are other systems that saw success in earlier days of the sport, such as blow-forward and pneumatically actuated recocking. In electropneumatic designs, the trigger, instead of being mechanically linked to the action of the marker activates an electronic microswitch; that information is passed through control circuitry to a computer-controlled solenoid valve which can open and close quickly and allowing gas to move into or out of various pressure chambers in the marker to move the bolt and fire the paintball.
This disconnect of the trigger from the action allows electronic trigger pulls to be short in length and lightweight, which increases rate-of-fire over a mechanical design. Solenoid-controlled gas valve designs allow for reduced weight of internal parts, which both lightens overall weight and reduces the time it takes for the marker to cycle through firing a single paintball. In electropneumatic designs, there are two primary mechanism types: The "poppet valve" design functions to a mechanical blowback or Autococker-style marker. Either additional air from the solenoid in a "two-way" design, or a spring in a "FASOR" design, returns the bolt and ram to the open position. Another paintball drops into the open chamber and the action is ready to fire again. Poppets are valued for high gas efficiency, as the low-pressure system to move the ram and the limited time the high-pressure valve is open saves gas compared to most competing designs. However, the nature of the mechanism produces loud "pops" when the marker is fired, the movement of the ram and bolt and the sudden high-pressure release of air can increase recoil, affecting accuracy during rapid fire.
They are more mechanically complex. The "spool valve" uses the bolt itself to hold air in a filling chamber; this high-pressure air is either self-balancing so there is no net force to open the bolt, or is kept in check by additional air from the solenoid pushing backward on the bolt. When the trigger is pulled, the solenoid of a balanced system pushes the bolt forward, or in a dump-valve vents the air from the forward pressure chamber; as the bolt moves forward, it seals off the inlet allowing high-pressure gas into the filling chamber, releases the stored charge of air through the bolt into the main chamber to launch the ball. The solenoid resets the bolt by allowing air to re-enter the forward chamber and pushing the bolt backwards to re-seal the filling chamber and open the inlet. Spool valves are valued for their quieter and smoother operation, their reduced mechanical complexity, but are less gas-efficient than poppet valves due to the large charge of air behind the bolt and the single operating pressure used both to move the bolt and l
A gun is a ranged weapon designed to pneumatically discharge projectiles that are solid but can be liquid or charged particles and may be free-flying or tethered. The means of projectile propulsion vary according to designs, but are traditionally effected by a high gas pressure contained within a shooting tube, produced either through the rapid combustion of propellants, or by mechanical compression; the high-pressure gas is introduced behind the projectile, accelerating it down the length of the tube, imparting sufficient launch velocity to sustain its further travel towards the target once the propelling gas ceases acting upon it at the end of the tube. Alternatively, acceleration via electromagnetic field generation may be employed, in which case the shooting tube may be substituted by guide rails or wrapped with magnetic coils; the first devices identified as guns appeared in China from around CE 1000. By the 12th century, the technology was spreading through the rest of Asia, into Europe by the 13th century.
The origin of the English word gun is considered to derive from the name given to a particular historical weapon. Domina Gunilda was the name given to a remarkably large ballista, a mechanical bolt throwing weapon of enormous size, mounted at Windsor Castle during the 14th century; this name in turn may have derived from the Old Norse woman's proper name Gunnhildr which combines two Norse words referring to battle. In any case the term gonne or gunne was applied to early hand-held firearms by the late 14th or early 15th century; the first device identified as a gun, a bamboo tube that used gunpowder to fire a spear, appeared in China around AD 1000. The Chinese had invented gunpowder in the 9th century. An early type of firearm is the fire lance, a black-powder–filled tube attached to the end of a spear and used as a flamethrower; the earliest depiction of a gunpowder weapon is the illustration of a fire-lance on a mid-10th century silk banner from Dunhuang. The De'an Shoucheng Lu, an account of the siege of De'an in 1132, records that Song forces used fire-lances against the Jurchens.
In due course, the proportion of saltpeter in the propellant was increased to maximise its explosive power. To better withstand that explosive power, the paper and bamboo of which fire-lance barrels were made came to be replaced by metal, and to take full advantage of that power, the shrapnel came to be replaced by projectiles whose size and shape filled the barrel more closely. With this, we have the three basic features of the gun: a barrel made of metal, high-nitrate gunpowder, a projectile which occludes the muzzle so that the powder charge exerts its full potential in propellant effect. Breech-loading guns called cetbang were used by the Majapahit Empire during the conquest of Nusantara in 1336–1350; the knowledge of making powder weapons in Java is thought to have originated from the Mongol invasion in 1293. These swivel guns mounted on various vessels of the Majapahit navy were used to great effect against traditional boarding-style warfare of other kingdoms in the archipelago. One theory of how gunpowder came to Europe is that it made its way along the Silk Road through the Middle East.
English Privy Wardrobe accounts list "ribaldis", a type of cannon, in the 1340s, siege guns were used by the English at Calais in 1346. The earliest surviving firearm in Europe has been found from Otepää, Estonia and it dates to at least 1396. Around the late 14th century in Europe and portable hand-held cannons were developed, creating in effect the first smooth-bore personal firearm. In the late 15th century the Ottoman empire used firearms as part of its regular infantry; the first successful rapid-fire firearm is the Gatling Gun, invented by Richard Gatling and fielded by the Union forces during the American Civil War in the 1860s. The world's first sub-machine gun able to be maneuvered by a single soldier is the MP18.1, invented by Theodor Bergmann. It was introduced into service in 1918 by the German Army during World War I as the primary weapon of the Stosstruppen; the first assault rifle was introduced during World War II by the Germans, known as the StG44. It was the first firearm which bridges the gap between long range rifles, machine guns, short range sub-machine guns.
Since the mid-20th century guns that fire beams of energy rather than solid projectiles have been developed, guns that can be fired by means other than the use of gunpowder. Most guns use compressed gas confined by the barrel to propel the bullet up to high speed, though devices operating in other ways are sometimes called guns. In firearms the high-pressure gas is generated by combustion of gunpowder; this principle is similar to that of internal combustion engines, except that the bullet leaves the barrel, while the piston transfers its motion to other parts and returns down the cylinder. As in an internal combustion engine, the combustion propagates by deflagration rather than by detonation, the optimal gunpowder, like the optimal motor fuel, is resistant to detonation; this is because much of the energy generated in detonation is in the form of a shock wave, which can propagate from the gas to the solid structure and heat or damage the structure, rathe