1.
Vapor
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A vapor is different from an aerosol. An aerosol is a suspension of particles of liquid, solid. For example, water has a temperature of 647 K. In the atmosphere at ordinary temperatures, therefore, gaseous water will condense into a liquid if its pressure is increased sufficiently. A vapor may co-exist with a liquid, when this is true, the two phases will be in equilibrium, and the gas-partial pressure will be equal to the equilibrium vapor pressure of the liquid. Vapor refers to a gas phase at a temperature where the substance can also exist in the liquid or solid state. If the vapor is in contact with a liquid or solid phase, the term gas refers to a compressible fluid phase. Fixed gases are gases for which no liquid or solid can form at the temperature of the gas, a liquid or solid does not have to boil to release a vapor. Vapor is responsible for the processes of cloud formation and condensation. It is commonly employed to carry out the processes of distillation. The constituent molecules of a vapor possess vibrational, rotational, and these motions are considered in the kinetic theory of gases. The vapor pressure is the pressure from a liquid or a solid at a specific temperature. The equilibrium vapor pressure of a liquid or solid is not affected by the amount of contact with the liquid or solid interface, the normal boiling point of a liquid is the temperature at which the vapor pressure is equal to normal atmospheric pressure. For two-phase systems, the pressure of the individual phases are equal. The total vapor pressure is the sum of the component partial pressures, perfumes contain chemicals that vaporize at different temperatures and at different rate in scent accords known as notes. Atmospheric water vapor is found near the surface, and may condense into small liquid droplets and form meteorological phenomena such as fog, mist. Mercury-vapor lamps and sodium vapor lamps produce light from atoms in excited states, flammable liquids do not burn when ignited. It is the cloud above the liquid that will burn if the vapors concentration is between the lower flammable limit and upper flammable limit of the flammable liquid
2.
Liquid
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A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a constant volume independent of pressure. As such, it is one of the four states of matter. A liquid is made up of tiny vibrating particles of matter, such as atoms, water is, by far, the most common liquid on Earth. Like a gas, a liquid is able to flow and take the shape of a container, most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, a distinctive property of the liquid state is surface tension, leading to wetting phenomena. The density of a liquid is usually close to that of a solid, therefore, liquid and solid are both termed condensed matter. On the other hand, as liquids and gases share the ability to flow, although liquid water is abundant on Earth, this state of matter is actually the least common in the known universe, because liquids require a relatively narrow temperature/pressure range to exist. Most known matter in the universe is in form as interstellar clouds or in plasma form within stars. Liquid is one of the four states of matter, with the others being solid, gas. Unlike a solid, the molecules in a liquid have a greater freedom to move. The forces that bind the molecules together in a solid are only temporary in a liquid, a liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, if liquid is placed in a bag, it can be squeezed into any shape. These properties make a suitable for applications such as hydraulics. Liquid particles are bound firmly but not rigidly and they are able to move around one another freely, resulting in a limited degree of particle mobility. As the temperature increases, the vibrations of the molecules causes distances between the molecules to increase. When a liquid reaches its point, the cohesive forces that bind the molecules closely together break. If the temperature is decreased, the distances between the molecules become smaller, only two elements are liquid at standard conditions for temperature and pressure, mercury and bromine. Four more elements have melting points slightly above room temperature, francium, caesium, gallium and rubidium, metal alloys that are liquid at room temperature include NaK, a sodium-potassium metal alloy, galinstan, a fusible alloy liquid, and some amalgams
3.
Water vapor
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Water vapor, water vapour or aqueous vapor, is the gaseous phase of water. It is one state of water within the hydrosphere, water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Unlike other forms of water, water vapor is invisible, under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. It is lighter than air and triggers convection currents that can lead to clouds, use of water vapor, as steam, has been important to humans for cooking and as a major component in energy production and transport systems since the industrial revolution. Likewise the detection of water vapor would indicate a similar distribution in other planetary systems. Water vapor is significant in that it can be evidence supporting the presence of extraterrestrial liquid water in the case of some planetary mass objects. Whenever a water molecule leaves a surface and diffuses into a surrounding gas, each individual water molecule which transitions between a more associated and a less associated state does so through the absorption or release of kinetic energy. The aggregate measurement of kinetic energy transfer is defined as thermal energy. Liquid water that becomes water vapor takes a parcel of heat with it, the amount of water vapor in the air determines how fast each molecule will return to the surface. When a net evaporation occurs, the body of water will undergo a net cooling directly related to the loss of water, in the US, the National Weather Service measures the actual rate of evaporation from a standardized pan open water surface outdoors, at various locations nationwide. Others do likewise around the world, the US data is collected and compiled into an annual evaporation map. The measurements range from under 30 to over 120 inches per year, formulas can be used for calculating the rate of evaporation from a water surface such as a swimming pool. In some countries, the evaporation rate far exceeds the precipitation rate, evaporative cooling is restricted by atmospheric conditions. Humidity is the amount of vapor in the air. The vapor content of air is measured with devices known as hygrometers, the measurements are usually expressed as specific humidity or percent relative humidity. This condition is referred to as complete saturation. Humidity ranges from 0 gram per cubic metre in dry air to 30 grams per cubic metre when the vapor is saturated at 30 °C, another form of evaporation is sublimation, by which water molecules become gaseous directly, leaving the surface of ice without first becoming liquid water. Sublimation accounts for the slow disappearance of ice and snow at temperatures too low to cause melting
4.
Cloud chamber
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The cloud chamber, also known as the Wilson chamber, is a particle detector used for detecting ionizing radiation. In its most basic form, a chamber is a sealed environment containing a supersaturated vapor of water or alcohol. When a charged particle interacts with the mixture, the fluid is ionized, the resulting ions act as condensation nuclei, around which a mist will form. The high energies of alpha and beta particles mean that a trail is left, Cloud chambers played a prominent role in the experimental particle physics from the 1920s to the 1950s, until the advent of the bubble chamber. In particular, the discoveries of the positron in 1932, the muon in 1936, Anderson detected the positron and muon in cosmic rays. Charles Thomson Rees Wilson, a Scottish physicist, is credited with inventing the cloud chamber, inspired by sightings of the Brocken spectre while working on the summit of Ben Nevis in 1894, he began to develop expansion chambers for studying cloud formation and optical phenomena in moist air. Very rapidly he discovered that ions could act as centers for water droplet formation in such chambers and he pursued the application of this discovery and perfected the first cloud chamber in 1911. When an ionizing particle passes through the chamber, water condenses on the resulting ions. Wilson, along with Arthur Compton, received the Nobel Prize in Physics in 1927 for his work on the cloud chamber and this kind of chamber is also called a Pulsed Chamber because the conditions for operation are not continuously maintained. Further developments were made by Patrick Blackett who utilised a stiff spring to expand and compress the chamber very rapidly, a cine film was used to record the images. The diffusion cloud chamber was developed in 1936 by Alexander Langsdorf, instead of water vapor, alcohol is used because of its lower freezing point. Cloud chambers cooled by dry ice are a demonstration and hobbyist device. There are also water-cooled diffusion cloud chambers, using ethylene glycol, a simple cloud chamber consists of the sealed environment, radioactive source, dry ice or a cold plate and some kind of alcohol source. The alcohol falls as it cools down and the cold condenser provides a steep temperature gradient, the result is a supersaturated environment. The alcohol vapor condenses around ion trails left behind by the travelling ionizing particles, the result is cloud formation, seen in the cloud chamber by the presence of droplets falling down to the condenser. As particles pass through they leave ionization trails and because the vapor is supersaturated it condenses onto these trails. Since the tracks are emitted radially out from the source, their point of origin can easily be determined, just above the cold condenser plate there is an area of the chamber which is sensitive to radioactive tracks. At this height, most of the alcohol has not condensed and this means that the ion trail left by the radioactive particles provides an optimal trigger for condensation and cloud formation
5.
Supersaturation
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Supersaturation is a state of a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances. It can also refer to a vapor of a compound that has a higher pressure than the pressure of that compound. Special conditions need to be met in order to generate a supersaturated solution, one of the easiest ways to do this relies on the temperature dependence of solubility. As a general rule, the heat is added to a system. Therefore, at high temperatures, more solute can be dissolved than at room temperature, the precipitation or crystallization of the solute takes longer than the actual cooling time because the molecules need to meet up and form the precipitate without being knocked apart by water. Thus, the larger the molecule, the longer it will take to crystallize due to the principles of Brownian motion, the condition of supersaturation does not necessarily have to be reached through the manipulation of heat. The ideal gas law suggests that pressure and volume can also be changed to force a system into a supersaturated state, if the volume of solvent is decreased, the concentration of the solute can be above the saturation point and thus create a supersaturated solution. The decrease in volume is most commonly generated through evaporation, similarly, an increase in pressure can drive a solution to a supersaturated state. All three of these rely on the fact that the conditions of the solution can be changed quicker than the solute can precipitate or crystallize out. Supersaturated solutions will also undergo crystallization under specific conditions, in a normal solution, once the maximum amount of solute is dissolved, adding more solute would either cause the dissolved solute to precipitate out and/or for the solute to not dissolve at all. Similarly, there are cases wherein solubility of a solution is decreased by manipulating temperature, pressure, or volume. In these cases, the solute will simply precipitate out and this is due to the fact that a supersaturated solution is in a higher energy state than a saturated solution. Crystallization will occur to allow the solution to reach an energy state. The activation energy comes in the form of a crystal being added to the liquid solution. This nuclei can be added from another source, which is known as seeding, or can spontaneously form within the solution due partly to ion. This process is known as primary nucleation and it is necessary for the nuclei to be identical to the solute that is crystallizing. This will allow for the ions to build up on the nuclei. There are a multitude of factors that affect the rate and order of magnitude with which crystallization proceeds as well as the difference in formation of crystallites
6.
Cloud seeding
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The usual intent is to increase precipitation, but hail and fog suppression are also widely practiced in airports. Cloud seeding also occurs due to ice nucleators in nature, most of which are bacterial in origin, the most common chemicals used for cloud seeding include silver iodide, potassium iodide and dry ice. Liquid propane, which expands into a gas, has also been used and this can produce ice crystals at higher temperatures than silver iodide. After promising research, the use of materials, such as table salt, is becoming more popular. When Cloud seeding increases snowfall takes place when temperatures within the clouds are between 19 and −4 °F, introduction of a substance such as silver iodide, which has a crystalline structure similar to that of ice, will induce freezing nucleation. In mid-latitude clouds, the usual seeding strategy has been based on the fact that the vapor pressure is lower over ice than over water. The formation of ice particles in super cooled clouds allows those particles to grow at the expense of liquid droplets, if sufficient growth takes place, the particles become heavy enough to fall as precipitation from clouds that otherwise would produce no precipitation. This process is known as static seeding, Seeding of warm-season or tropical cumulonimbus clouds seeks to exploit the latent heat released by freezing. Cloud seeding chemicals may be dispersed by aircraft or by dispersion devices located on the ground, for release by aircraft, silver iodide flares are ignited and dispersed as an aircraft flies through the inflow of a cloud. When released by devices on the ground, the particles are carried downwind. An electronic mechanism was tested in 2010, when infrared laser pulses were directed to the air above Berlin by researchers from the University of Geneva, the experimenters posited that the pulses would encourage atmospheric sulfur dioxide and nitrogen dioxide to form particles that would then act as seeds. Cloud seeding has never been proven to work. Claims are made that new technology and research has produced results that make cloud seeding a dependable and affordable water supply practice for many regions. But while practiced widely around the world, the effectiveness of cloud seeding is still a matter of academic debate, in 2003 the US National Research Council released a report stating. science is unable to say with assurance which, if any, seeding techniques produce positive effects. In the 55 years following the first cloud-seeding demonstrations, substantial progress has made in understanding the natural processes that account for our daily weather. Yet scientifically acceptable proof for significant seeding effects has not been achieved, referring to 1903,1915,1919,1944, and 1947 weather modification experiments, the Australian Federation of Meteorology discounted rain making. By the 1950s, the CSIRO Division of Radiophysics switched to investigating the physics of clouds and had hoped by 1957 to better understand these processes. By the 1960s, the dreams of making had faded only to be re-ignited post-corporatisation of the Snowy Mountains Scheme in order to achieve above target water
7.
Climate engineering
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Climate engineering is an umbrella term for two types of measures, carbon dioxide removal and solar radiation management. Carbon dioxide removal addresses the cause of change by removing one of the greenhouse gases from the atmosphere. Solar radiation management attempts to offset effects of gases by causing the Earth to absorb less solar radiation. Climate engineering approaches are sometimes viewed as potential options for limiting climate change. There is substantial agreement among scientists that climate engineering cannot substitute for climate change mitigation, some approaches might be used as accompanying measures to sharp cuts in greenhouse gas emissions. Research on costs, benefits, and various types of risks of most climate engineering approaches is at a stage and their understanding needs to improve to judge their adequacy. Almost all research into solar radiation management has consisted of computer modelling or laboratory tests, some carbon dioxide removal practices, such as planting of trees and bio-energy with carbon capture and storage projects, are underway. Their scalability to effectively affect global climate is, however, debated, ocean iron fertilization has been given small-scale research trials, sparking substantial controversy. However, most experts also argue that the risks of such interventions must be seen in the context of risks of climate change. Groups such as ETC Group and some researchers are in favour of a moratorium on out-of-doors testing. With respect to climate, geoengineering is defined by the Royal Society as, the deliberate large-scale intervention in the Earth’s climate system, in order to moderate global warming. The Asilomar International Conference on Climate Intervention Technologies was convened to identify, some authors have argued that any public support for climate engineering may weaken the fragile political consensus to reduce greenhouse gas emissions. Several climate engineering strategies have been proposed, IPCC documents detail several notable proposals. These fall into two categories, solar radiation management and carbon dioxide removal. Here is a list of specific proposals, Solar radiation management techniques would seek to reduce sunlight absorbed. This would be achieved by deflecting sunlight away from the Earth and these methods would not reduce greenhouse gas concentrations in the atmosphere, and thus would not seek to address problems such as the ocean acidification caused by CO2. Furthermore, many proposed SRM methods would be reversible in their direct climatic effects, while greenhouse gas remediation offers a more comprehensive possible solution to climate change, it does not give instantaneous results, for that, solar radiation management is required. Solar radiation management methods may include, Surface-based, for example, using pale-colored roofing materials, attempting to change the oceans brightness, troposphere-based, for example, marine cloud brightening, which would spray fine sea water to whiten clouds and thus increase cloud reflectivity
8.
Particulates
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Atmospheric particulate matter – also known as particulate matter or particulates – are microscopic solid or liquid matter suspended in the Earths atmosphere. The term aerosol commonly refers to the mixture, as opposed to the particulate matter alone. Sources of particulate matter can be man-made or natural and they have impacts on climate and precipitation that adversely affect human health. The smaller PM2.5 were particularly deadly, with a 36% increase in lung cancer per 10 μg/m3 as it can penetrate deeper into the lungs, some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes, coal combustion in developing countries is the primary method for heating homes and supplying energy. The composition of aerosols and particles depends on their source, wind-blown mineral dust tends to be made of mineral oxides and other material blown from the Earths crust, this particulate is light-absorbing. In addition, sea spray aerosols may contain organic compounds, which influence their chemistry, Secondary particles derive from the oxidation of primary gases such as sulfur and nitrogen oxides into sulfuric acid and nitric acid. The gases from which they originate—may have an origin and a natural biogenic origin. In the presence of ammonia, secondary aerosols often take the form of ammonium salts and this is mainly because the presence of sulfate and nitrate causes the aerosols to increase to a size that scatters light effectively. Organic matter can be primary or secondary, the latter part deriving from the oxidation of VOCs. Organic matter influences the atmospheric radiation field by both scattering and absorption, another important aerosol type is elemental carbon, this aerosol type includes strongly light-absorbing material and is thought to yield large positive radiative forcing. Organic matter and elemental carbon together constitute the carbonaceous fraction of aerosols, Secondary organic aerosols, tiny tar balls resulting from combustion products of internal combustion engines, have been identified as a danger to health. The chemical composition of the aerosol directly affects how it interacts with solar radiation, the chemical constituents within the aerosol change the overall refractive index. The refractive index will determine how light is scattered and absorbed. The particles are hygroscopic due to the presence of sulfur, and SO2 is converted to sulfate when high humidity and this causes the reduced visibility and yellow color. Aerosol particles of natural origin tend to have a larger radius than human-produced aerosols such as particle pollution, the false-color maps in the third image on this page show where there are natural aerosols, human pollution, or a mixture of both, monthly. Most of the Southern Hemisphere is covered by ocean, where the largest source of aerosols is natural sea salt from dried sea spray. Because land is concentrated in the Northern Hemisphere, the amount of small aerosols from fires, over land, patches of large-radius aerosols appear over deserts and arid regions, most prominently, the Sahara Desert in north Africa and the Arabian Peninsula, where dust storms are common
9.
Clay
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Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to water content and become hard, brittle. Depending on the content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size, silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in size and other physical properties. The distinction between silt and clay varies by discipline, geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm, sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils Atterberg limits, ISO14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. These solvents, usually acidic, migrate through the rock after leaching through upper weathered layers. In addition to the process, some clay minerals are formed through hydrothermal activity. There are two types of deposits, primary and secondary. Primary clays form as residual deposits in soil and remain at the site of formation, secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with very low energy depositional environments such as large lakes. Depending on the source, there are three or four main groups of clays, kaolinite, montmorillonite-smectite, illite, and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a group within the phyllosilicates. There are approximately 30 different types of clays in these categories. Varve is clay with visible annual layers, which are formed by deposition of those layers and are marked by differences in erosion. This type of deposit is common in glacial lakes
10.
Soot
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Soot /ˈsʊt/ is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. Soot causes cancer and lung disease, and is the second-biggest human cause of global warming, Soot as an airborne contaminant in the environment has many different sources, all of which are results of some form of pyrolysis. Soot in very low concentrations is capable of darkening surfaces or making particle agglomerates, such as those from ventilation systems, Soot is the primary cause of ghosting, the discoloration of walls and ceilings or walls and flooring where they meet. It is generally responsible for the discoloration of the walls above baseboard electric heating units, the formation of soot depends strongly on the fuel composition. The rank ordering of sooting tendency of fuel components is, naphthalenes → benzenes → aliphatics, however, the order of sooting tendencies of the aliphatics varies dramatically depending on the flame type. The difference between the tendencies of aliphatics and aromatics is thought to result mainly from the different routes of formation. The formation of soot is a process, an evolution of matter in which a number of molecules undergo many chemical and physical reactions within a few milliseconds. Soot is a form of amorphous carbon. Gas-phase soot contains polycyclic aromatic hydrocarbons, the PAHs in soot are known mutagens and are classified as a known human carcinogen by the International Agency for Research on Cancer. Soot forms during incomplete combustion from precursor molecules such as acetylene and it consists of agglomerated nanoparticles with diameters between 6 and 30 ㎚. The soot particles can be mixed with metal oxides and with minerals, many details of soot formation chemistry remain unanswered and controversial, but there have been a few agreements, Soot begins with some precursors or building blocks. Nucleation of heavy molecules occurs to form particles, surface growth of a particle proceeds by adsorption of gas phase molecules. Coagulation happens via reactive particle–particle collisions, oxidation of the molecules and soot particles reduces soot formation. Soot, particularly diesel exhaust pollution, accounts for one quarter of the total hazardous pollution in the air. Among these diesel emission components, particulate matter has been a concern for human health due to its direct. In earlier times, health professionals associated PM10 with chronic disease, lung cancer, influenza, asthma. However, recent scientific studies suggest that these correlations be more linked with fine particles. Long-term exposure to air pollution containing soot increases the risk of coronary artery disease
11.
Sulfate
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The sulfate or sulphate ion is a polyatomic anion with the empirical formula SO2−4. Sulfate is the spelling recommended by IUPAC, but sulphate is used in British English, salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life, sulfates are salts of sulfuric acid and many are prepared from that acid. The sulfate anion consists of a sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement. The symmetry is the same as that of methane, the sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the state. The sulfate ion carries a charge of −2 and it is the conjugate base of the bisulfate ion, HSO−4. Organic sulfate esters, such as sulfate, are covalent compounds. The tetrahedral molecular geometry of the ion is as predicted by VSEPR theory. Later, Linus Pauling used valence bond theory to propose that the most significant resonance canonicals had two pi bonds involving d orbitals and his reasoning was that the charge on sulfur was thus reduced, in accordance with his principle of electroneutrality. The S−O bond length of 149 pm is shorter than the bond lengths in sulfuric acid of 157 pm for S−OH, the double bonding was taken by Pauling to account for the shortness of the S−O bond. Paulings use of d orbitals provoked a debate on the importance of π bonding. The outcome was a consensus that d orbitals play a role. A widely accepted description involving pπ – dπ bonding was initially proposed by D. W. J. Cruickshank, in this model, fully occupied p orbitals on oxygen overlap with empty sulfur d orbitals. However, in description, despite there being some π character to the S−O bonds. For sulfuric acid, computational analysis confirms a positive charge on sulfur. Therefore, the representation with four single bonds is the optimal Lewis structure rather than the one with two double bonds, in this model, the structure obeys the octet rule and the charge distribution is in agreement with the electronegativity of the atoms. However, the representation of Pauling for sulfate and other main group compounds with oxygen is still a common way of representing the bonding in many textbooks. On the other hand, in the structure with an ionic bond, exceptions include calcium sulfate, strontium sulfate, lead sulfate, and barium sulfate, which are poorly soluble
12.
Volcano
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A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earths volcanoes occur because its crust is broken into 17 major, therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. This type of volcanism falls under the umbrella of plate hypothesis volcanism, Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called hotspots, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the boundary,3,000 km deep in the Earth. Volcanoes are usually not created where two plates slide past one another. Erupting volcanoes can pose hazards, not only in the immediate vicinity of the eruption. Historically, so-called volcanic winters have caused catastrophic famines, the word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology. The study of volcanoes is called volcanology, sometimes spelled vulcanology, at the mid-oceanic ridges, two tectonic plates diverge from one another as new oceanic crust is formed by the cooling and solidifying of hot molten rock. Most divergent plate boundaries are at the bottom of the oceans, therefore, most volcanic activity is submarine, black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the temperature of the overlying mantle wedge. This magma tends to be very viscous due to its high content, so it often does not reach the surface. When it does reach the surface, a volcano is formed, typical examples of this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire. Because tectonic plates move across them, each volcano becomes dormant and is eventually re-formed as the plate advances over the postulated plume and this theory is currently under criticism, however. The most common perception of a volcano is of a mountain, spewing lava and poisonous gases from a crater at its summit, however. The features of volcanoes are more complicated and their structure. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have features such as massive plateaus
13.
Phytoplankton
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Phytoplankton /ˌfaɪtoʊˈplæŋktən/ are the autotrophic components of the plankton community and a key part of oceans, seas and freshwater basin ecosystems. The name comes from the Greek words φυτόν, meaning plant, most phytoplankton are too small to be individually seen with the unaided eye. Phytoplankton are photosynthesizing microscopic organisms that inhabit the upper layer of almost all oceans. They are agents for primary production, the creation of organic compounds from carbon dioxide dissolved in the water, Phytoplankton obtain energy through the process of photosynthesis and must therefore live in the well-lit surface layer of an ocean, sea, lake, or other body of water. Phytoplankton account for half of all activity on Earth. Their cumulative energy fixation in carbon compounds is the basis for the vast majority of oceanic, the effects of anthropogenic warming on the global population of phytoplankton is an area of active research. Additionally, changes in the mortality of phytoplankton due to rates of zooplankton grazing may be significant, as a side note, one of the more remarkable food chains in the ocean – remarkable because of the small number of links – is that of phytoplankton-feeding krill feeding baleen whales. Phytoplankton are also dependent on minerals. However, across large regions of the World Ocean such as the Southern Ocean and this has led to some scientists advocating iron fertilization as a means to counteract the accumulation of human-produced carbon dioxide in the atmosphere. Large-scale experiments have added iron to the oceans to promote phytoplankton growth, however, controversy about manipulating the ecosystem and the efficiency of iron fertilization has slowed such experiments. Phytoplankton depend on other substances to survive as well, in particular, Vitamin B is crucial. Areas in the ocean have been identified as having a lack of Vitamin B. While almost all species are obligate photoautotrophs, there are some that are mixotrophic and other. Of these, the best known are dinoflagellate genera such as Noctiluca and Dinophysis, the term phytoplankton encompasses all photoautotrophic microorganisms in aquatic food webs. Phytoplankton serve as the base of the food web, providing an essential ecological function for all aquatic life. However, unlike terrestrial communities, where most autotrophs are plants, phytoplankton are a group, incorporating protistan eukaryotes. There are about 5,000 known species of marine phytoplankton, how such diversity evolved despite scarce resources is unclear. In terms of numbers, the most important groups of phytoplankton include the diatoms, cyanobacteria and dinoflagellates, one group, the coccolithophorids, is responsible for the release of significant amounts of dimethyl sulfide into the atmosphere
14.
Hygroscopy
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Hygroscopy is the phenomenon of attracting and holding water molecules from the surrounding environment, which is usually at normal or room temperature. This is achieved through either absorption or adsorption with the absorbing or adsorbing substance becoming physically changed somewhat. Zinc chloride and calcium chloride, as well as potassium hydroxide and sodium hydroxide, are so hygroscopic that they readily dissolve in the water they absorb, not only is sulfuric acid hygroscopic in concentrated form but its solutions are hygroscopic down to concentrations of 10 Vol-% or below. A hygroscopic material will tend to damp and cakey when exposed to moist air. Because of their affinity for moisture, hygroscopic materials might require storage in sealed containers. When added to foods or other materials for the purpose of maintaining moisture content. Materials and compounds exhibit different hygroscopic properties, and this difference can lead to detrimental effects, differences in hygroscopy can be observed in plastic-laminated paperback book covers—often, in a suddenly moist environment, the book cover will curl away from the rest of the book. The unlaminated side of the cover absorbs more moisture than the side and increases in area. This is similar to the function of a thermostats bi-metallic strip, inexpensive dial-type hygrometers make use of this principle using a coiled strip. Deliquescence, the process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water, deliquescence occurs when the vapour pressure of the solution that is formed is less than the partial pressure of water vapour in the air. While some similar forces are at work here, it is different from capillary attraction, a process where glass or other solid substances attract water, the similar-sounding but unrelated word hydroscopic is sometimes used in error for hygroscopic. A hydroscope is a device used for making observations deep under water. The amount of moisture held by hygroscopic materials is proportional to the relative humidity. Tables containing this information can be found in engineering handbooks and is also available from suppliers of various materials and chemicals. Hygroscopy also plays an important role in the engineering of plastic materials, some plastics are hygroscopic while others are not. The seeds of grasses have hygroscopic extensions that bend with changes in humidity. An example is Needle-and-Thread, Hesperostipa comata, each seed has an awn that twists several turns when the seed is released. Increased moisture causes it to untwist, and, upon drying, to twist again, thorny dragons collect moisture in the dry desert via nighttime condensation of dew that forms on their skin and is channeled to their mouths in hygroscopic grooves between the spines of their skin
15.
Ice nucleus
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An ice nucleus is a particle which acts as the nucleus for the formation of an ice crystal in the atmosphere. There are a number of mechanisms of ice nucleation in the atmosphere through which ice nuclei can catalyse the formation of ice particles, in the upper troposphere, water vapor can deposit directly onto solid particle. In clouds warmer than about −37 °C where liquid water can persist in a supercooled state, in the absence of an ice nucleating particle, pure water droplets can persist in a supercooled state to temperatures approaching −37 °C where they freeze homogeneously. Ice particles can have a significant effect on cloud dynamics and they are known to be important in the processes by which clouds can become electrified, which causes lightning. They are also known to be able to form the seeds for rain droplets, however, the exact nucleation potential of each type varies greatly, depending on the exact atmospheric conditions. Bergeron process Cloud condensation nuclei Nucleation Snow Supercooling
16.
Climate change
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Climate change is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time. Climate change may refer to a change in weather conditions. Climate change is caused by such as biotic processes, variations in solar radiation received by Earth, plate tectonics. Certain human activities have also identified as significant causes of recent climate change. Scientists actively work to understand past and future climate by using observations, more recent data are provided by the instrumental record. The most general definition of change is a change in the statistical properties of the climate system when considered over long periods of time. Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, the term climate change is often used to refer specifically to anthropogenic climate change. Anthropogenic climate change is caused by activity, as opposed to changes in climate that may have resulted as part of Earths natural processes. In this sense, especially in the context of environmental policy, within scientific journals, global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels affect. A related term is climatic change, in 1966, the World Meteorological Organization proposed the term climatic change to encompass all forms of climatic variability on time-scales longer than 10 years, regardless of cause. Change was a given and climatic was used as an adjective to describe this kind of change, when it was realized that human activities had a potential to drastically alter the climate, the term climate change replaced climatic change as the dominant term to reflect an anthropogenic cause. Climate change was incorporated in the title of the Intergovernmental Panel on Climate Change, Climate change, used as a noun, became an issue rather than the technical description of changing weather. On the broadest scale, the rate at which energy is received from the Sun and this energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions. Factors that can shape climate are called climate forcings or forcing mechanisms, there are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the system, such as the oceans and ice caps, respond more slowly in reaction to climate forcings. There are also key factors which when exceeded can produce rapid change. Forcing mechanisms can be internal or external. Internal forcing mechanisms are natural processes within the system itself
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Solar cycle
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The solar cycle or solar magnetic activity cycle is the nearly periodic 11-year change in the Suns activity and appearance. They have been observed for centuries, the changes on the sun cause effects in space, in the atmosphere, and on Earths surface. While it is the dominant variable in solar activity, aperiodic fluctuations also occur, Solar cycles have an average duration of about 11 years. Solar maximum and solar minimum refer respectively to periods of maximum and minimum sunspot counts, cycles span from one minimum to the next. The solar cycle was discovered in 1843 by Samuel Heinrich Schwabe, following Wolfs numbering scheme, the 1755–1766 cycle is traditionally numbered 1. Wolf created a standard sunspot number index, the Wolf index, the period between 1645 and 1715, a time of few sunspots, is known as the Maunder minimum, after Edward Walter Maunder, who extensively researched this peculiar event, first noted by Gustav Spörer. In the second half of the nineteenth century Richard Carrington and by Spörer independently noted the phenomena of sunspots appearing at different latitudes at different parts of the cycle, the cycles physical basis was elucidated by Hale and collaborators, who in 1908 showed that sunspots were strongly magnetized. In 1919 they showed that the polarity of sunspot pairs, Is constant throughout a cycle, Is opposite across the equator throughout a cycle. Hales observations revealed that the complete magnetic cycle spans two solar cycles, or 22 years, before returning to its original state, however, because nearly all manifestations are insensitive to polarity, the 11-year solar cycle remains the focus of research. In 1961 the father-and-son team of Harold and Horace Babcock established that the cycle is a spatiotemporal magnetic process unfolding over the Sun as a whole. Horaces Babcock model described the Suns oscillatory magnetic field, with a periodicity of 22 years. It covered the exchange of energy between poloidal and toroidal solar magnetic field ingredients. The level of activity beginning in the 1940s is exceptional – the last period of similar magnitude occurred around 9,000 years ago. The Sun was at a high level of magnetic activity for only ~10% of the past 11,400 years. Almost all earlier high-activity periods were shorter than the present episode, fossil records suggest that the Solar cycle has been stable for at least the last 290 million years. For example, the cycle length during the early Permian is estimated to be 10.62 years, since observations began, cycles have ranged from 9–14 years. The current solar cycle began on January 4,2008, with minimal activity until early 2010 and it is on track to have the lowest recorded sunspot activity since accurate records began in 1750. The cycle featured a double-peaked solar maximum, the first peak reached 99 in 2011 and the second in early 2014 at 101
18.
Cosmic ray
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Cosmic rays are high-energy radiation, mainly originating outside the Solar System. Upon impact with the Earths atmosphere, cosmic rays can produce showers of particles that sometimes reach the surface. Composed primarily of protons and atomic nuclei, they are of mysterious origin. Data from the Fermi space telescope have been interpreted as evidence that a significant fraction of cosmic rays originate from the supernovae explosions of stars. Active galactic nuclei probably also produce cosmic rays, the term ray is a historical accident, as cosmic rays were at first, and wrongly, thought to be mostly electromagnetic radiation. In current usage, the cosmic ray almost exclusively refers to massive particles. Massive particles – those that have rest mass – can gain additional, kinetic, mass-energy when they are moving, through this process, some particles acquire tremendously high mass-energies. These are significantly higher than the energy of even the highest-energy photons detected to date. The energy of the massless photon depends solely on frequency, not speed, at the higher end of the energy spectrum, relativistic kinetic energy is the main source of the mass-energy of cosmic rays. Hence, the highest-energy detected fermionic cosmic ray was around 3×106 times more energetic than the highest-energy detected cosmic photons, of primary cosmic rays, which originate outside of Earths atmosphere, about 99% are the nuclei of well-known atoms, and about 1% are solitary electrons. Of the nuclei, about 90% are simple protons, i. e. hydrogen nuclei, 9% are alpha particles, identical to helium nuclei, a very small fraction are stable particles of antimatter, such as positrons or antiprotons. The precise nature of this fraction is an area of active research. An active search from Earth orbit for anti-alpha particles has failed to detect them, one can show that such enormous energies might be achieved by means of the Centrifugal mechanism of acceleration in Active galactic nuclei. At 50 J, the highest-energy ultra-high-energy cosmic rays have energies comparable to the energy of a 90-kilometre-per-hour baseball. As a result of discoveries, there has been interest in investigating cosmic rays of even greater energies. Most cosmic rays, however, do not have such extreme energies, however, his paper published in Physikalische Zeitschrift was not widely accepted. In 1911 Domenico Pacini observed simultaneous variations of the rate of ionization over a lake, over the sea, Pacini concluded from the decrease of radioactivity underwater that a certain part of the ionization must be due to sources other than the radioactivity of the Earth. In 1912, Victor Hess carried three enhanced-accuracy Wulf electrometers to an altitude of 5300 meters in a balloon flight
19.
CLAW hypothesis
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The CLAW hypothesis proposes a negative feedback loop that operates between ocean ecosystems and the Earths climate. The CLAW hypothesis was proposed by Robert Jay Charlson, James Lovelock, Meinrat Andreae and Stephen G. Warren. Certain phytoplankton, such as coccolithophorids, synthesise dimethylsulfoniopropionate, and their enhanced growth increases the production of this osmolyte, in turn, this leads to an increase in the concentration of its breakdown product, dimethyl sulfide, first in seawater, and then in the atmosphere. DMS is oxidised in the atmosphere to form sulfur dioxide, and these aerosols act as cloud condensation nuclei and increase cloud droplet number, which in turn elevate the liquid water content of clouds and cloud area. This acts to increase albedo, leading to greater reflection of incident sunlight. The figure to the shows a summarising schematic diagram. Some subsequent studies of the CLAW hypothesis have uncovered evidence to support its mechanism, other researchers have suggested that a CLAW-like mechanism may operate in the Earths sulfur cycle without the requirement of an active biological component. Under future global warming, increasing temperature may stratify the world ocean, consequently, phytoplankton activity will decline with a concomitant fall in the production of DMS. In a reverse of the CLAW hypothesis, this decline in DMS production will lead to a decrease in cloud condensation nuclei, the consequence of this will be further climate warming which may lead to even less DMS production. The figure to the shows a summarising schematic diagram. Evidence for the hypothesis is constrained by similar uncertainties as those of the sulfur cycle feedback loop of the CLAW hypothesis. Earth science Geophysiology Iron fertilization Gaia and CLAW, Max Planck Institute for Chemistry, Mainz DMS and climate, Pacific Marine Environmental Laboratory, Seattle
20.
Methanesulfonic acid
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Methanesulfonic acid is a colorless liquid with the chemical formula CH3SO3H. It is the simplest of the alkylsulfonic acids, salts and esters of methanesulfonic acid are known as mesylates. It is hygroscopic in its concentrated form, methanesulfonic acid may be considered an intermediate compound between sulfuric acid, and methylsulfonylmethane, effectively replacing an –OH group with a –CH3 group at each step. This pattern can no further in either direction without breaking down the –SO2– group. Methanesulfonic acid can dissolve a wide range of salts, many of them in significantly higher concentrations than in hydrochloric or sulphuric acid. Methanesulfonic acid is used as an acid catalyst in organic reactions because it is a non-volatile, methanesulfonic acid is convenient for industrial applications because it is liquid at ambient temperature, while the closely related p-toluenesulfonic acid is solid. However, in a setting, solid PTSA is more convenient. Methanesulfonic acid can be used in the generation of borane by reacting methanesulfonic acid with NaBH4 in a solvent such as THF or DMS, the complex of BH3. Methanesulfonic acid is also the electrolyte of choice in zinc-cerium and lead-acid flow batteries, methanesulfonic acid is also a primary ingredient in rust and scale removers. It is used to clean off surface rust from ceramic, tiles and porcelain which are usually susceptible to acid attack
21.
Algal bloom
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An algal bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems, and is recognized by the discoloration in the water from their pigments. Cyanobacteria were mistaken for algae in the past, so cyanobacterial blooms are also called algal blooms. Blooms which can injure animals or the ecology are called harmful algal blooms, since algae is a broad term including organisms of widely varying sizes, growth rates and nutrient requirements, there is no officially recognized threshold level as to what is defined as a bloom. For some species, algae can be considered to be blooming at concentrations reaching millions of cells per milliliter, bright green blooms in freshwater systems are frequently a result of cyanobacteria such as Microcystis. Blooms may also consist of macroalgal species and these blooms are recognizable by large blades of algae that may wash up onto the shoreline. Such blooms often take on a red or brown hue and are known colloquially as red tides, freshwater algal blooms are the result of an excess of nutrients, particularly some phosphates. The excess of nutrients may originate from fertilizers that are applied to land for agricultural or recreational purposes and they may also originate from household cleaning products containing phosphorus. These nutrients can then enter watersheds through water runoff, excess carbon and nitrogen have also been suspected as causes. Presence of residual sodium carbonate acts as catalyst for the algae to bloom by providing dissolved carbon dioxide for enhanced photosynthesis in the presence of nutrients, when phosphates are introduced into water systems, higher concentrations cause increased growth of algae and plants. Algae tend to very quickly under high nutrient availability, but each alga is short-lived. The decay process consumes dissolved oxygen in the water, resulting in hypoxic conditions, without sufficient dissolved oxygen in the water, animals and plants may die off in large numbers. Use of an Olszewski tube can help combat problems with hypolimnetic withdrawal. Blooms may be observed in freshwater aquariums when fish are overfed and these are generally harmful for fish, and the situation can be corrected by changing the water in the tank and then reducing the amount of food given. A harmful algal bloom is a bloom that causes negative impacts to other organisms via production of natural toxins, mechanical damage to other organisms. HABs are often associated with large-scale marine mortality events and have associated with various types of shellfish poisonings. In studies at the population level bloom coverage has been related to the risk of non-alcoholic liver disease death. In the marine environment, single-celled, microscopic, plant-like organisms naturally occur in the surface layer of any body of water. These organisms, referred to as phytoplankton or microalgae, form the base of the food web upon which all other marine organisms depend
22.
The Revenge of Gaia
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The Revenge of Gaia, Why the Earth is Fighting Back – and How we Can Still Save Humanity is a book by James Lovelock. Some editions of the book have a different, less optimistic subtitle, Earths Climate Crisis, the book introduces the concept of the anti-CLAW hypothesis. Lovelock proposed that instead of providing negative feedback in the climate system, under future global warming, increasing temperature may stratify the world ocean, decreasing the supply of nutrients from the deep ocean to its productive euphotic zone. Consequently, phytoplankton activity will decline with a concomitant fall in the production of DMS, in a reverse of the CLAW hypothesis, this decline in DMS production will lead to a decrease in cloud condensation nuclei and a fall in cloud albedo. The consequence of this will be further climate warming which may lead to even less DMS production, the figure to the right shows a summarising schematic diagram. Evidence for the hypothesis is constrained by similar uncertainties as those of the sulfur cycle feedback loop of the CLAW hypothesis. Risks to civilisation, humans and planet Earth Richard Mabey reviews The Revenge of Gaia No atom of doubt, edited extract from The Guardian,24 March 2006
23.
James Lovelock
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James Ephraim Lovelock CH CBE FRS is an independent scientist, environmentalist and futurist who lives in Devon, England. He is best known for proposing the Gaia hypothesis, which postulates that the Earth functions as a self-regulating system, James Lovelock was born in Letchworth Garden City in Hertfordshire, England, to working class parents who were strong believers in education. Nell, his mother, started work at 13 in a pickle factory and his father, Tom, had served six months hard labour for poaching in his teens and was illiterate until attending technical college. The family moved to London, where Lovelocks dislike of authority made him, by his own account, Lovelock could not afford to go to university after school, something which he believes helped prevent him becoming over-specialised and aided the development of Gaia theory. Lovelock worked at a Quaker farm before a recommendation from his professor led to him taking up a Medical Research Council post, working on ways of shielding soldiers from burns. Lovelock refused to use the shaved and anaesthetised rabbits that were used as burn victims, and exposed his own skin to heat radiation instead and his student status enabled temporary deferment of military service during the Second World War, but he registered as a conscientious objector. He later abandoned this position in the light of Nazi atrocities, and tried to enlist in the armed forces, in 1948 Lovelock received a PhD degree in medicine at the London School of Hygiene and Tropical Medicine. In the United States, he has conducted research at Yale, Baylor College of Medicine, a lifelong inventor, Lovelock has created and developed many scientific instruments, some of which were designed for NASA in its program of planetary exploration. It was while working as a consultant for NASA that Lovelock developed the Gaia Hypothesis and he also claims to have invented the microwave oven. In early 1961, Lovelock was engaged by NASA to develop instruments for the analysis of extraterrestrial atmospheres. During work on a precursor of this program, Lovelock became interested in the composition of the Martian atmosphere, reasoning that many life forms on Mars would be obliged to make use of it. However, the atmosphere was found to be in a condition close to its chemical equilibrium, with very little oxygen, methane, or hydrogen. To Lovelock, the stark contrast between the Martian atmosphere and chemically dynamic mixture of that of the Earths biosphere was strongly indicative of the absence of life on the planet, however, when they were finally launched to Mars, the Viking probes still searched for extant life there. Lovelock invented the electron capture detector, which assisted in discoveries about the persistence of CFCs. Lovelock was elected a Fellow of the Royal Society in 1974 and he served as the president of the Marine Biological Association from 1986 to 1990, and has been an Honorary Visiting Fellow of Green Templeton College, Oxford since 1994. H. Heineken Prize for the Environment and the Royal Geographical Society Discovery Lifetime award, in 2006 he received the Wollaston Medal, the Geological Societys highest Award, whose previous recipients include Charles Darwin. He became a Commander of the Order of the British Empire CBE in 1990, and he is a patron of population concern charity Population Matters. On 8 May 2012, he appeared on the Radio Four series The Life Scientific, on the program, he mentioned how his ideas had been received by various people, including Jonathan Porritt
24.
Stratification (water)
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These layers are normally arranged according to density, with the least dense water masses sitting above the more dense layers. Water stratification also creates barriers to nutrient mixing between layers and this can affect the primary production in an area by limiting photosynthetic processes. When nutrients from the benthos cannot travel up into the photic zone, lower primary production also leads to lower net productivity in waters. Stratification may be upset by turbulence and this creates mixed layers of water. Forms of turbulence may include surface friction, upwelling and downwelling. Marshall et al. suggest that baroclinic eddies may be an important factor in maintaining stratification, canfield ocean Cline Lake stratification Meromictic
25.
Photosynthesis
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Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms activities. In most cases, oxygen is released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis, such organisms are called photoautotrophs, in plants, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, in the Calvin cycle, atmospheric carbon dioxide is incorporated into already existing organic carbon compounds, such as ribulose bisphosphate. Using the ATP and NADPH produced by the light-dependent reactions, the compounds are then reduced and removed to form further carbohydrates. Cyanobacteria appeared later, the oxygen they produced contributed directly to the oxygenation of the Earth. Today, the rate of energy capture by photosynthesis globally is approximately 130 terawatts. Photosynthetic organisms also convert around 100–115 thousand million tonnes of carbon into biomass per year. Photosynthetic organisms are photoautotrophs, which means that they are able to synthesize food directly from carbon dioxide, however, not all organisms that use light as a source of energy carry out photosynthesis, photoheterotrophs use organic compounds, rather than carbon dioxide, as a source of carbon. In plants, algae, and cyanobacteria, photosynthesis releases oxygen and this is called oxygenic photosynthesis and is by far the most common type of photosynthesis used by living organisms. Although there are differences between oxygenic photosynthesis in plants, algae, and cyanobacteria, the overall process is quite similar in these organisms. There are also varieties of anoxygenic photosynthesis, used mostly by certain types of bacteria. Carbon dioxide is converted into sugars in a process called carbon fixation, photosynthesis provides the energy in the form of free electrons that are used to split carbon from carbon dioxide that is then used to fix that carbon once again as carbohydrate. Carbon fixation is a redox reaction, so photosynthesis supplies the energy that drives both process. In the first stage, light-dependent reactions or light reactions capture the energy of light and use it to make the energy-storage molecules ATP, during the second stage, the light-independent reactions use these products to capture and reduce carbon dioxide. Most organisms that utilize oxygenic photosynthesis use visible light for the light-dependent reactions, some organisms employ even more radical variants of photosynthesis. Some archea use a method that employs a pigment similar to those used for vision in animals. The bacteriorhodopsin changes its configuration in response to sunlight, acting as a proton pump and this produces a proton gradient more directly, which is then converted to chemical energy
26.
Albedo
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Albedo is a measure for reflectance or optical brightness. It is dimensionless and measured on a scale from zero to one, surface albedo is defined as the ratio of radiation reflected to the radiation incident on a surface. The proportion reflected is not only determined by properties of the surface itself and these factors vary with atmospheric composition, geographic location and time. While bi-hemispherical reflectance is calculated for an angle of incidence. The temporal resolution may range from seconds to daily, seasonal or annual averages, unless given for a specific wavelength, albedo refers to the entire spectrum of solar radiation. Due to measurement constraints, it is given for the spectrum in which most solar energy reaches the surface. This spectrum includes visible light, which explains why surfaces with a low albedo appear dark, albedo is an important concept in climatology, astronomy, and environmental management. The term albedo was introduced into optics by Johann Heinrich Lambert in his 1760 work Photometria, any albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances. Deeply shadowed cavities can achieve an effective albedo approaching the zero of a black body, when seen from a distance, the ocean surface has a low albedo, as do most forests, whereas desert areas have some of the highest albedos among landforms. Most land areas are in a range of 0.1 to 0.4. The average albedo of Earth is about 0.3 and this is far higher than for the ocean primarily because of the contribution of clouds. Earths surface albedo is regularly estimated via Earth observation satellite sensors such as NASAs MODIS instruments on board the Terra, thereby, the BRDF allows to translate observations of reflectance into albedo. Earths average surface temperature due to its albedo and the effect is currently about 15 °C. If Earth were frozen entirely, the temperature of the planet would drop below −40 °C. If only the land masses became covered by glaciers, the mean temperature of the planet would drop to about 0 °C. In contrast, if the entire Earth was covered by water — a so-called aquaplanet — the average temperature on the planet would rise to almost 27 °C, hence, the actual albedo α can then be given as, α = α ¯ + D α ¯ ¯. Directional-hemispherical reflectance is sometimes referred to as black-sky albedo and bi-hemispherical reflectance as white-sky albedo and these terms are important because they allow the albedo to be calculated for any given illumination conditions from a knowledge of the intrinsic properties of the surface. The albedos of planets, satellites and asteroids can be used to infer much about their properties, the study of albedos, their dependence on wavelength, lighting angle, and variation in time comprises a major part of the astronomical field of photometry
27.
Evapotranspiration
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Evapotranspiration is the sum of evaporation and plant transpiration from the Earths land and ocean surface to the atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, transpiration accounts for the movement of water within a plant and the subsequent loss of water as vapor through stomata in its leaves. Evapotranspiration is an important part of the water cycle, an element that contributes to evapotranspiration can be called an evapotranspirator. It is a reflection of the energy available to evaporate water, actual evapotranspiration is said to equal reference evapotranspiration when there is ample water. Some US states utilize a full cover alfalfa reference crop that is 0.5 m in height, rather than the green grass reference. Evapotranspiration is a significant water loss from drainage basins, types of vegetation and land use significantly affect evapotranspiration, and therefore the amount of water leaving a drainage basin. Because water transpired through leaves comes from the roots, plants with deep reaching roots can more constantly transpire water, herbaceous plants generally transpire less than woody plants because they usually have less extensive foliage. Conifer forests tend to have higher rates of evapotranspiration than deciduous forests, particularly in the dormant and this is primarily due to the enhanced amount of precipitation intercepted and evaporated by conifer foliage during these periods. Factors that affect evapotranspiration include the growth stage or level of maturity, percentage of soil cover, solar radiation, humidity, temperature. Isotope measurements indicate transpiration is the component of evapotranspiration. Through evapotranspiration, forests reduce water yield, except in unique ecosystems called cloud forests, trees in cloud forests collect the liquid water in fog or low clouds onto their surface, which drips down to the ground. These trees still contribute to evapotranspiration, but often more water than they evaporate or transpire. In areas that are not irrigated, actual evapotranspiration is usually no greater than precipitation and it will usually be less because some water will be lost due to percolation or surface runoff. An exception is areas with water tables, where capillary action can cause water from the groundwater to rise through the soil matrix to the surface. If potential evapotranspiration is greater than precipitation, then soil will dry out. Evapotranspiration can never be greater than PET, but can be if there is not enough water to be evaporated or plants are unable to transpire readily. Evapotranspiration can be measured or estimated using several methods, pan evaporation data can be used to estimate lake evaporation, but transpiration and evaporation of intercepted rain on vegetation are unknown. There are three approaches to estimate evapotranspiration indirectly
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Global dimming
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Global dimming is the gradual reduction in the amount of global direct irradiance at the Earths surface that was observed for several decades after the start of systematic measurements in the 1950s. The effect varies by location, but worldwide it has estimated to be of the order of a 4% reduction over the three decades from 1960–1990. However, after discounting an anomaly caused by the eruption of Mount Pinatubo in 1991, global dimming is thought to have been caused by an increase in particulates such as sulfate aerosols in the atmosphere due to human action. It has interfered with the cycle by reducing evaporation and may have reduced rainfall in some areas. Global dimming also creates an effect that may have partially counteracted the effect of greenhouse gases on global warming. It is thought that global dimming is probably due to the presence of aerosol particles in the atmosphere caused by human action. Aerosols and other particulates absorb solar energy and reflect back into space. The pollutants can also become nuclei for cloud droplets, water droplets in clouds coalesce around the particles. Increased pollution causes more particulates and thereby creates clouds consisting of a number of smaller droplets. The smaller droplets make clouds more reflective, so that more incoming sunlight is reflected back into space and this same effect also reflects radiation from below, trapping it in the lower atmosphere. In models, these smaller droplets also decrease rainfall, clouds intercept both heat from the sun and heat radiated from the Earth. Their effects are complex and vary in time, location, in the late-1960s, Mikhail Ivanovich Budyko worked with simple two-dimensional energy-balance climate models to investigate the reflectivity of ice. He found that the ice-albedo feedback created a feedback loop in the Earths climate system. The more snow and ice, the solar radiation is reflected back into space and hence the colder Earth grows. Other studies found that pollution or an eruption could provoke the onset of an ice age. His findings appeared to contradict global warming — the global temperature had been rising since the 70s. Less light reaching the earth seemed to mean that it should cool, ohmura published his findings Secular variation of global radiation in Europe in 1989. Dimming has also observed in sites all over the former Soviet Union
29.
Seed crystal
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A seed crystal is a small piece of single crystal / polycrystal material from which a large crystal of the same material typically is to be grown. The theory behind this effect is thought to derive from the physical interaction that occurs between compounds in a supersaturated solution. In solution, liberated molecules are free to move about in random flow and this random flow permits for the possibility of two or more molecular compounds to interact. This interaction can potentiate intermolecular forces between the molecules and form a basis for a crystal lattice. The placement of a seed crystal into solution allows the process to expedite by eliminating the need for random molecular collision / interaction. By introducing an already pre-formed basis of the crystal to act upon. Often, this transition from solute in a solution to a crystal lattice will be referred to as nucleation. Seeding is therefore said to decrease the amount of time needed for nucleation to occur in a recrystallization process. Crystal structure Crystallization Laser heated pedestal growth Micro-pulling-down Single crystal Wafer
30.
Water cycle
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The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth. In doing so, the water goes through different forms, liquid, solid, the water cycle involves the exchange of energy, which leads to temperature changes. For instance, when water evaporates, it takes up energy from its surroundings, when it condenses, it releases energy and warms the environment. The evaporative phase of the cycle purifies water which then replenishes the land with freshwater, the flow of liquid water and ice transports minerals across the globe. It is also involved in reshaping the geological features of the Earth, the water cycle is also essential for the maintenance of most life and ecosystems on the planet. The sun, which drives the cycle, heats water in oceans. Water evaporates as water vapor into the air, ice and snow can sublimate directly into water vapour. Evapotranspiration is water transpired from plants and evaporated from the soil, the water vapour molecule H 2O has less density compared to the major components of the atmosphere, nitrogen and oxygen, N2 andO2. Due to the significant difference in mass, water vapor in gas form gains height in open air as a result of buoyancy. However, as increases, air pressure decreases and the temperature drops. The lowered temperature causes water vapour to condense into a liquid water droplet which is heavier than the air. A huge concentration of these droplets over a space up in the atmosphere become visible as cloud. Fog is formed if the water vapour condenses near ground level, as a result of moist air, air currents move water vapour around the globe, cloud particles collide, grow, and fall out of the upper atmospheric layers as precipitation. Some precipitation falls as snow or hail, sleet, and can accumulate as ice caps and glaciers, most water falls back into the oceans or onto land as rain, where the water flows over the ground as surface runoff. A portion of runoff enters rivers in valleys in the landscape, runoff and water emerging from the ground may be stored as freshwater in lakes. Not all runoff flows into rivers, much of it soaks into the ground as infiltration, some water infiltrates deep into the ground and replenishes aquifers, which can store freshwater for long periods of time. Some infiltration stays close to the surface and can seep back into surface-water bodies as groundwater discharge. Some groundwater finds openings in the surface and comes out as freshwater springs
31.
Adiabatic process
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In thermodynamics, an adiabatic process is one that occurs without transfer of heat or matter between a thermodynamic system and its surroundings. In an adiabatic process, energy is transferred only as work, the adiabatic process provides a rigorous conceptual basis for the theory used to expound the first law of thermodynamics, and as such it is a key concept in thermodynamics. The adiabatic flame temperature is the temperature that would be achieved by a if the process of combustion took place in the absence of heat loss to the surroundings. A process that does not involve the transfer of heat or matter into or out of a system, so that Q =0, is called an adiabatic process, the assumption that a process is adiabatic is a frequently made simplifying assumption. Even though the cylinders are not insulated and are quite conductive, the same can be said to be true for the expansion process of such a system. The assumption of adiabatic isolation of a system is a useful one, the behaviour of actual machines deviates from these idealizations, but the assumption of such perfect behaviour provide a useful first approximation of how the real world works. According to Laplace, when sound travels in a gas, there is no loss of heat in the medium and the propagation of sound is adiabatic. For this adiabatic process, the modulus of elasticity E = γP where γ is the ratio of specific heats at constant pressure and at constant volume, such a process is called an isentropic process and is said to be reversible. Fictively, if the process is reversed, the energy added as work can be recovered entirely as work done by the system, if the walls of a system are not adiabatic, and energy is transferred in as heat, entropy is transferred into the system with the heat. Such a process is neither adiabatic nor isentropic, having Q >0, naturally occurring adiabatic processes are irreversible. The transfer of energy as work into an isolated system can be imagined as being of two idealized extreme kinds. In one such kind, there is no entropy produced within the system, in nature, this ideal kind occurs only approximately, because it demands an infinitely slow process and no sources of dissipation. The other extreme kind of work is work, for which energy is added as work solely through friction or viscous dissipation within the system. The second law of thermodynamics observes that a process, of transfer of energy as work, always consists at least of isochoric work. Every natural process, adiabatic or not, is irreversible, with ΔS >0, the adiabatic compression of a gas causes a rise in temperature of the gas. Adiabatic expansion against pressure, or a spring, causes a drop in temperature, in contrast, free expansion is an isothermal process for an ideal gas. Adiabatic heating occurs when the pressure of a gas is increased from work done on it by its surroundings and this finds practical application in diesel engines which rely on the lack of quick heat dissipation during their compression stroke to elevate the fuel vapor temperature sufficiently to ignite it. Adiabatic heating occurs in the Earths atmosphere when an air mass descends, for example, in a wind, Foehn wind
32.
Buoyancy
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In science, buoyancy or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid, thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object and this pressure difference results in a net upwards force on the object. For this reason, an object whose density is greater than that of the fluid in which it is submerged tends to sink, If the object is either less dense than the liquid or is shaped appropriately, the force can keep the object afloat. This can occur only in a reference frame, which either has a gravitational field or is accelerating due to a force other than gravity defining a downward direction. In a situation of fluid statics, the net upward force is equal to the magnitude of the weight of fluid displaced by the body. The center of buoyancy of an object is the centroid of the volume of fluid. Archimedes principle is named after Archimedes of Syracuse, who first discovered this law in 212 B. C, more tersely, Buoyancy = weight of displaced fluid. The weight of the fluid is directly proportional to the volume of the displaced fluid. Thus, among completely submerged objects with equal masses, objects with greater volume have greater buoyancy and this is also known as upthrust. Suppose a rocks weight is measured as 10 newtons when suspended by a string in a vacuum with gravity acting upon it, suppose that when the rock is lowered into water, it displaces water of weight 3 newtons. The force it exerts on the string from which it hangs would be 10 newtons minus the 3 newtons of buoyancy force,10 −3 =7 newtons. Buoyancy reduces the apparent weight of objects that have sunk completely to the sea floor and it is generally easier to lift an object up through the water than it is to pull it out of the water. The density of the object relative to the density of the fluid can easily be calculated without measuring any volumes. Density of object density of fluid = weight weight − apparent immersed weight Example, If you drop wood into water, Example, A helium balloon in a moving car. During a period of increasing speed, the air mass inside the car moves in the direction opposite to the cars acceleration, the balloon is also pulled this way. However, because the balloon is buoyant relative to the air, it ends up being pushed out of the way, If the car slows down, the same balloon will begin to drift backward. For the same reason, as the car goes round a curve and this is the equation to calculate the pressure inside a fluid in equilibrium
33.
Lightning
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Lightning is a sudden electrostatic discharge that occurs during a thunder storm. This discharge occurs between electrically charged regions of a cloud, between two clouds, or between a cloud and the ground. The charged regions in the atmosphere temporarily equalize themselves through this discharge referred to as an if it hits an object on the ground. Lightning causes light in the form of plasma, and sound in the form of thunder, Lightning may be seen and not heard when it occurs at a distance too great for the sound to carry as far as the light from the strike or flash. This article incorporates public domain material from the National Oceanic and Atmospheric Administration document Understanding Lightning, the details of the charging process are still being studied by scientists, but there is general agreement on some of the basic concepts of thunderstorm electrification. The main charging area in a thunderstorm occurs in the part of the storm where air is moving upward rapidly and temperatures range from -15 to -25 Celsius. At that place, the combination of temperature and rapid upward air movement produces a mixture of super-cooled cloud droplets, small ice crystals, the updraft carries the super-cooled cloud droplets and very small ice crystals upward. At the same time, the graupel, which is larger and denser. The differences in the movement of the precipitation cause collisions to occur, when the rising ice crystals collide with graupel, the ice crystals become positively charged and the graupel becomes negatively charged. The updraft carries the positively charged ice crystals upward toward the top of the storm cloud, the larger and denser graupel is either suspended in the middle of the thunderstorm cloud or falls toward the lower part of the storm. The result is that the part of the thunderstorm cloud becomes positively charged while the middle to lower part of the thunderstorm cloud becomes negatively charged. This part of the cloud is called the anvil. While this is the charging process for the thunderstorm cloud. In addition, there is a small but important positive charge buildup near the bottom of the cloud due to the precipitation. Many factors affect the frequency, distribution, strength and physical properties of a lightning flash in a particular region of the world. These factors include ground elevation, latitude, prevailing wind currents, relative humidity, proximity to warm and cold bodies of water, to a certain degree, the ratio between IC, CC and CG lightning may also vary by season in middle latitudes. Lightnings relative unpredictability limits a complete explanation of how or why it occurs, the actual discharge is the final stage of a very complex process. At its peak, a thunderstorm produces three or more strikes to the Earth per minute
34.
Solar radiation
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Solar irradiance is the power per unit area received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Irradiance may be measured in space or at the Earths surface after atmospheric absorption and it is measured perpendicular to the incoming sunlight. Total solar irradiance, is a measure of the power over all wavelengths per unit area incident on the Earths upper atmosphere. The solar constant is a measure of mean TSI at a distance of one astronomical Unit. Irradiance is a function of distance from the Sun, the solar cycle, Irradiance on Earth is also measured perpendicular to the incoming sunlight. Insolation is the received on Earth per unit area on a horizontal surface. It depends on the height of the Sun above the horizon, the solar irradiance integrated over time is called solar irradiation, solar exposure or insolation. However, insolation is often used interchangeably with irradiance in practice, the SI unit of irradiance is watt per square meter. An alternate unit of measure is the Langley per unit time, the solar energy industry uses watt-hour per square metre per unit time, the relation to the SI unit is thus 1 kW/m2 =24 kWh/m2/day =8760 kWh/m2/year. Irradiance can also be expressed in Suns, where one Sun equals 1000 W/m2 at the point of arrival, part of the radiation reaching an object is absorbed and the remainder reflected. Usually the absorbed radiation is converted to energy, increasing the objects temperature. Manmade or natural systems, however, can convert part of the radiation into another form such as electricity or chemical bonds. The proportion of reflected radiation is the objects reflectivity or albedo, insolation onto a surface is largest when the surface directly faces the sun. As the angle between the surface and the Sun moves from normal, the insolation is reduced in proportion to the angles cosine, see effect of sun angle on climate. In the figure, the angle shown is between the ground and the rather than between the vertical direction and the sunbeam, hence the sine rather than the cosine is appropriate. A sunbeam one mile wide arrives from directly overhead, and another at a 30° angle to the horizontal, the sine of a 30° angle is 1/2, whereas the sine of a 90° angle is 1. Therefore, the angled sunbeam spreads the light over twice the area, consequently, half as much light falls on each square mile. This projection effect is the reason why Earths polar regions are much colder than equatorial regions
35.
Surface weather analysis
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Surface weather analysis is a special type of weather map that provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations. The first weather maps in the 19th century were drawn well after the fact to help devise a theory on storm systems, use of surface analyses began first in the United States, spreading worldwide during the 1870s. Use of the Norwegian cyclone model for frontal analysis began in the late 1910s across Europe, surface weather analyses have special symbols that show frontal systems, cloud cover, precipitation, or other important information. For example, an H may represent high pressure, implying clear skies, an L, on the other hand, may represent low pressure, which frequently accompanies precipitation. Various symbols are used not just for frontal zones and other surface boundaries on weather maps, areas of precipitation help determine the frontal type and location. The use of charts in a modern sense began in the middle portion of the 19th century in order to devise a theory on storm systems. The development of a network by 1845 made it possible to gather weather information from multiple distant locations quickly enough to preserve its value for real-time applications. The Smithsonian Institution developed its network of observers over much of the central, the U. S. Army Signal Corps inherited this network between 1870 and 1874 by an act of Congress, and expanded it to the west coast soon afterwards. The weather data was at first less useful as a result of the different times at which weather observations were made, the first attempts at time standardization took hold in Great Britain by 1855. The entire United States did not finally come under the influence of time zones until 1905, other countries followed the lead of the United States in taking simultaneous weather observations, starting in 1873. Other countries then began preparing surface analyses, the use of frontal zones on weather maps did not appear until the introduction of the Norwegian cyclone model in the late 1910s, despite Loomis earlier attempt at a similar notion in 1841. Since the leading edge of air mass changes bore resemblance to the fronts of World War I. The effort to automate map plotting began in the United States in 1969, hong Kong completed their process of automated surface plotting by 1987. In the United States, this development was achieved when Intergraph workstations were replaced by n-AWIPS workstations, recent advances in both the fields of meteorology and geographic information systems have made it possible to devise finely tailored weather maps. Weather information can quickly be matched to relevant geographical detail, for instance, icing conditions can be mapped onto the road network. This will likely continue to lead to changes in the way surface analyses are created and displayed over the several years. The pressureNET project is an attempt to gather surface pressure data using smartphones. When analyzing a weather map, a model is plotted at each point of observation
36.
Visibility
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In meteorology, visibility is a measure of the distance at which an object or light can be clearly discerned. It is reported within surface weather observations and METAR code either in meters or statute miles, visibility affects all forms of traffic, roads, sailing and aviation. Meteorological visibility refers to transparency of air, in dark, meteorological visibility is still the same as in daylight for the same air, note. — The two distances have different values in air of a given extinction coefficient, and the latter b) varies with the background illumination. The former a) is represented by the optical range. In extremely clean air in Arctic or mountainous areas, the visibility can be up to 161 kilometres where there are large markers such as mountains or high ridges, however, visibility is often reduced somewhat by air pollution and high humidity. Various weather stations report this as haze or mist, fog and smoke can reduce visibility to near zero, making driving extremely dangerous. The same can happen in a sandstorm in and near desert areas, heavy rain not only causes low visibility, but the inability to brake quickly due to hydroplaning. Blizzards and ground blizzards are also defined in part by low visibility, to define visibility the case of a perfectly black object being viewed against a perfectly white background is examined. Because the object is assumed to be black, it must absorb all of the light incident on it. Thus when x=0, F =0 and CV =1, between the object and the observer, F is affected by additional light that is scattered into the observers line of sight and the absorption of light by gases and particles. Light scattered by particles outside of a beam may ultimately contribute to the irradiance at the target. Unlike absorbed light, scattered light is not lost from a system, rather, it can change directions and contribute to other directions. It is only lost from the beam traveling in one particular direction. The multiple scatterings contribution to the irradiance at x is modified by the individual particle scattering coefficient, the concentration of particles. The intensity change dF is the result of effects over a distance dx. Because dx is a measure of the amount of suspended gases and particles, the fractional reduction in F is d F = − b ext F d x where bext is the attenuation coefficient. The scattering of light into the observers line of sight can increase F over the distance dx. This increase is defined as b FB dx, where b is a constant, the overall change in intensity is expressed as d F = d x Since FB represents the background intensity, it is independent of x by definition
37.
Vorticity
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Conceptually, vorticity could be determined by marking the part of continuum in a small neighborhood of the point in question, and watching their relative displacements as they move along the flow. The vorticity vector would be twice the angular velocity vector of those particles relative to their center of mass. This quantity must not be confused with the velocity of the particles relative to some other point. More precisely, the vorticity is a pseudovector field ω→, defined as the curl of the flow velocity u→ vector, the definition can be expressed by the vector analysis formula, ω → ≡ ∇ × u →, where ∇ is the del operator. The vorticity of a flow is always perpendicular to the plane of the flow. The vorticity is related to the flows circulation along a path by the Stokes theorem. Namely, for any infinitesimal surface element C with normal direction n→ and area dA, many phenomena, such as the blowing out of a candle by a puff of air, are more readily explained in terms of vorticity rather than the basic concepts of pressure and velocity. This applies, in particular, to the formation and motion of vortex rings, in a mass of continuum that is rotating like a rigid body, the vorticity is twice the angular velocity vector of that rotation. This is the case, for example, of water in a tank that has been spinning for a while around its vertical axis, the vorticity may be nonzero even when all particles are flowing along straight and parallel pathlines, if there is shear. The vorticity will be zero on the axis, and maximum near the walls, conversely, a flow may have zero vorticity even though its particles travel along curved trajectories. An example is the ideal irrotational vortex, where most particles rotate about some straight axis, another way to visualize vorticity is to imagine that, instantaneously, a tiny part of the continuum becomes solid and the rest of the flow disappears. If that tiny new solid particle is rotating, rather than just moving with the flow, mathematically, the vorticity of a three-dimensional flow is a pseudovector field, usually denoted by ω→, defined as the curl or rotational of the velocity field v→ describing the continuum motion. In Cartesian coordinates, ω → = ∇ × v → = × = In words, the evolution of the vorticity field in time is described by the vorticity equation, which can be derived from the Navier–Stokes equations. This is clearly true in the case of 2-D potential flow, Vorticity is a useful tool to understand how the ideal potential flow solutions can be perturbed to model real flows. In general, the presence of viscosity causes a diffusion of vorticity away from the vortex cores into the flow field. This flow is accounted for by the term in the vorticity transport equation. Thus, in cases of very viscous flows, the vorticity will be diffused throughout the flow field, a vortex line or vorticity line is a line which is everywhere tangent to the local vorticity vector. Vortex lines are defined by the relation d x ω x = d y ω y = d z ω z, a vortex tube is the surface in the continuum formed by all vortex-lines passing through a given closed curve in the continuum
38.
Wind
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Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the movement of air. Winds are commonly classified by their scale, their speed, the types of forces that cause them, the regions in which they occur. The strongest observed winds on a planet in the Solar System occur on Neptune, Winds have various aspects, an important one being its velocity, another the density of the gas involved, another its energy content or wind energy. In meteorology, winds are referred to according to their strength. Short bursts of high speed wind are termed gusts, strong winds of intermediate duration are termed squalls. Long-duration winds have various names associated with their strength, such as breeze, gale, storm. The two main causes of large-scale atmospheric circulation are the differential heating between the equator and the poles, and the rotation of the planet, within the tropics, thermal low circulations over terrain and high plateaus can drive monsoon circulations. In coastal areas the sea breeze/land breeze cycle can define local winds, in areas that have variable terrain, mountain, Wind powers the voyages of sailing ships across Earths oceans. Hot air balloons use the wind to take trips, and powered flight uses it to increase lift. Areas of wind caused by various weather phenomena can lead to dangerous situations for aircraft. When winds become strong, trees and man-made structures are damaged or destroyed, Winds can shape landforms, via a variety of aeolian processes such as the formation of fertile soils, such as loess, and by erosion. Wind also affects the spread of wildfires, Winds can disperse seeds from various plants, enabling the survival and dispersal of those plant species, as well as flying insect populations. When combined with temperatures, wind has a negative impact on livestock. Wind affects animals food stores, as well as their hunting, Wind is caused by differences in the atmospheric pressure. When a difference in atmospheric pressure exists, air moves from the higher to the pressure area. On a rotating planet, air will also be deflected by the Coriolis effect, globally, the two major driving factors of large-scale wind patterns are the differential heating between the equator and the poles and the rotation of the planet. Outside the tropics and aloft from frictional effects of the surface, near the Earths surface, friction causes the wind to be slower than it would be otherwise
