1.
Atmosphere of Earth
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The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earths gravity. The atmosphere of Earth protects life on Earth by absorbing solar radiation, warming the surface through heat retention. By volume, dry air contains 78. 09% nitrogen,20. 95% oxygen,0. 93% argon,0. 04% carbon dioxide, and small amounts of other gases. Air also contains an amount of water vapor, on average around 1% at sea level. The atmosphere has a mass of about 5. 15×1018 kg, the atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km, or 1. 57% of Earths radius, is used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km, several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition. The study of Earths atmosphere and its processes is called atmospheric science, early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann. The three major constituents of air, and therefore of Earths atmosphere, are nitrogen, oxygen, water vapor accounts for roughly 0. 25% of the atmosphere by mass. The remaining gases are often referred to as gases, among which are the greenhouse gases, principally carbon dioxide, methane, nitrous oxide. Filtered air includes trace amounts of other chemical compounds. Various industrial pollutants also may be present as gases or aerosols, such as chlorine, fluorine compounds, sulfur compounds such as hydrogen sulfide and sulfur dioxide may be derived from natural sources or from industrial air pollution. In general, air pressure and density decrease with altitude in the atmosphere, however, temperature has a more complicated profile with altitude, and may remain relatively constant or even increase with altitude in some regions. In this way, Earths atmosphere can be divided into five main layers, excluding the exosphere, Earth has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere. It extends from the exobase, which is located at the top of the thermosphere at an altitude of about 700 km above sea level, to about 10,000 km where it merges into the solar wind. This layer is composed of extremely low densities of hydrogen, helium and several heavier molecules including nitrogen, oxygen. The atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another, thus, the exosphere no longer behaves like a gas, and the particles constantly escape into space. These free-moving particles follow ballistic trajectories and may migrate in and out of the magnetosphere or the solar wind, the exosphere is located too far above Earth for any meteorological phenomena to be possible
2.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
3.
Hygrometer
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A hygrometer /haɪˈɡrɒmᵻtər/ is an instrument used for measuring the moisture content in the atmosphere. Humidity measurement instruments usually rely on measurements of some other quantity such as temperature, pressure, by calibration and calculation, these measured quantities can lead to a measurement of humidity. Modern electronic devices use temperature of condensation, or changes in electrical capacitance or resistance to measure humidity differences, the first crude hygrometer was invented by Leonardo da Vinci in 1480 and a more modern version was created by polymath Johann Heinrich Lambert in 1755. The metal-paper coil hygrometer is very useful for giving an indication of humidity changes. It appears most often in very inexpensive devices, and its accuracy is limited, in these devices, water vapour is absorbed by a salt-impregnated paper strip attached to a metal coil, causing the coil to change shape. These changes cause an indication on a dial and these devices use a human or animal hair under tension. The hair is hygroscopic, its length changes with humidity, in the late 1700s, such devices were called by some scientists hygroscopes, that word is no longer in current use, but hygroscopic and hygroscopy, which derive from it, still are. The traditional folk art known as a weather house works on this principle. Whale bone and other materials may be used in place of hair, in 1783, Swiss physicist and geologist Horace Bénédict de Saussure built the first hair-tension hygrometer using human hair. The pulley is connected to an index which moves over a graduated scale, the instrument can be made more sensitive by removing oils from the hair, such as by first soaking the hair in diethyl ether. A psychrometer, or wet-and-dry-bulb thermometer, consists of two thermometers, one that is dry and one that is kept moist with distilled water on a sock or wick. When the air temperature is below freezing, however, the wet-bulb is covered with a coating of ice. Relative humidity is computed from the ambient temperature as shown by the dry-bulb thermometer, relative humidity can also be determined by locating the intersection of the wet and dry-bulb temperatures on a psychrometric chart. The two thermometers coincide when the air is saturated, and the greater the difference the drier the air. Psychrometers are commonly used in meteorology, and in the HVAC industry for proper refrigerant charging of residential and commercial air conditioning systems, a whirling psychrometer uses the same principle, but the two thermometers are fitted into a device that resembles a ratchet or football rattle. Dew point is the temperature at which a sample of moist air at constant pressure reaches water vapor saturation, at this saturation temperature, further cooling results in condensation of water. Chilled mirror dewpoint hygrometers are some of the most precise instruments commonly available and they use a chilled mirror and optoelectronic mechanism to detect condensation on the mirrors surface. The temperature of the mirror is controlled by electronic feedback to maintain an equilibrium between evaporation and condensation, thus closely measuring the dew point temperature
4.
Frost
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Frost is the coating or deposit of ice that may form in humid air in cold conditions, usually overnight. In temperate climates it most commonly appears as white crystals or frozen dew drops near the ground. Frost is composed of delicate branched patterns of ice crystals formed as the result of fractal process development, Frost is known to damage crops or reduce future crop yields, therefore farmers in those regions where frost is a problem often invest substantial means to prevent its formation. In most temperate countries such temperatures usually are the result of loss by radiation at night. The size of frost crystals varies depending on the time they have been building up, Frost crystals may be clear or translucent, but, like snow, a mass of frost crystals will scatter light in all directions, so that a coating of frost appears white. If a solid surface is chilled below the dew point of the humid air. If the water deposits as a liquid that freezes, it forms a coating that may look glassy, opaque, or crystalline. Depending on context, that also may be called atmospheric icing. The ice it produces differs in ways from crystalline frost. For desublimation to proceed the surface must be below the frost point of the air, the air must be humid, but not sufficiently humid to permit the condensation of liquid water, or icing will result instead of desublimation. The size of the crystals depends largely on the temperature, the amount of water vapor available, as a rule, except in conditions where supercooled droplets are present in the air, frost will form only if the deposition surface is colder than the surrounding air. For instance frost may be observed around cracks in cold wooden sidewalks when humid air escapes from the ground beneath. Other objects on which frost commonly forms are those with low specific heat or high thermal emissivity, such as blackened metals, the apparently erratic occurrence of frost in adjacent localities is due partly to differences of elevation, the lower areas becoming colder on calm nights. Where static air settles above an area of ground in the absence of wind, hoar frost refers to white ice crystals, deposited on the ground or loosely attached to exposed objects such as wires or leaves. They form on cold, clear nights when conditions are such that heat radiates out to the sky faster than it can be replaced from nearby sources such as wind or warm objects. Under suitable circumstances, objects cool to below the frost point of the surrounding air, such freezing may be promoted by effects such as flood frost or frost pocket. These occur when ground-level radiation losses cool air till it flows downhill and accumulates in pockets of cold air in valleys. Hoar frost may freeze in such low-lying cold air even when the air temperature a few feet above ground is well above freezing
5.
Guttation
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Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses. Guttation is not to be confused with dew, which condenses from the atmosphere onto the plant surface, at night, transpiration usually does not occur because most plants have their stomata closed. When there is a soil moisture level, water will enter plant roots. The water will accumulate in the plant, creating a slight root pressure, the root pressure forces some water to exude through special leaf tip or edge structures, hydathodes or water glands, forming drops. Root pressure provides the impetus for this flow, rather than transpirational pull, guttation is most noticeable when transpiration is suppressed and the relative humidity is high, such as during the night. Guttation fluid may contain a variety of organic and inorganic compounds, mainly sugars, on drying, a white crust remains on the leaf surface. Concentrations this high are near those of active ingredients applied in field sprays for pest control and it was found that when bees consume guttation drops collected from plants grown from neonicotinoid-coated seeds, they die within a few minutes. This phenomenon may be a factor in bee deaths and, consequently, if high levels of nitrogen appear in the fluid, it is a sign of fertilizer burn. Excess nitrogen must be leached from the soil by addition of large quantities of water and this is the best way to restore soil fertility, but it may result in water pollution. Homeostasis Osmosis Soil plant atmosphere continuum Transpiration
6.
Fog
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Fog consists of visible cloud water droplets or ice crystals suspended in the air at or near the Earths surface. Fog can be considered a type of low-lying cloud and is influenced by nearby bodies of water, topography. In turn, fog has affected many human activities, such as shipping, travel, the term fog is typically distinguished from the more generic term cloud in that fog is low-lying, and the moisture in the fog is often generated locally. By definition, fog reduces visibility to less than 1 kilometre, for aviation purposes in the UK, a visibility of less than 5 kilometres but greater than 999 metres is considered to be mist if the relative humidity is 70% or greater, below 70%, haze is reported. Fog forms when the difference between air temperature and dew point is less than 2.5 °C or 4 °F, Fog begins to form when water vapor condenses into tiny liquid water droplets suspended in the air. Water vapor normally begins to condense on condensation nuclei such as dust, ice, Fog, like its elevated cousin stratus, is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. Fog normally occurs at a relative humidity near 100% and this occurs from either added moisture in the air, or falling ambient air temperature. However, fog can form at lower humidities, and can fail to form with relative humidity at 100%. At 100% relative humidity, the air cannot hold additional moisture, thus, Fog can form suddenly and can dissipate just as rapidly. The sudden formation of fog is known as flash fog, Fog commonly produces precipitation in the form of drizzle or very light snow. Drizzle occurs when the humidity of fog attains 100% and the cloud droplets begin to coalesce into larger droplets. This can occur when the fog layer is lifted and cooled sufficiently, drizzle becomes freezing drizzle when the temperature at the surface drops below the freezing point. The inversion boundary varies its altitude primarily in response to the weight of the air above it, the marine layer, and any fogbank it may contain, will be squashed when the pressure is high, and conversely, may expand upwards when the pressure above it is lowering. Fog can form in a number of ways, depending on how the cooling that caused the condensation occurred, radiation fog is formed by the cooling of land after sunset by thermal radiation in calm conditions with clear sky. The warm ground produces condensation in the air by heat conduction. In perfect calm the fog layer can be less than a meter deep, radiation fogs occur at night, and usually do not last long after sunrise, but they can persist all day in the winter months especially in areas bounded by high ground. Radiation fog is most common in autumn and early winter, examples of this phenomenon include the Tule fog. Ground fog is fog that obscures less than 60% of the sky, advection fog occurs when moist air passes over a cool surface by advection and is cooled
7.
Radiation
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In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles, Ionizing radiation carries more than 10 eV, which is enough to ionize atoms and molecules, and break chemical bonds. This is an important distinction due to the difference in harmfulness to living organisms. A common source of ionizing radiation is radioactive materials that emit α, β, or γ radiation, consisting of helium nuclei, electrons or positrons, gamma rays, X-rays and the higher energy range of ultraviolet light constitute the ionizing part of the electromagnetic spectrum. The lower-energy, longer-wavelength part of the spectrum including visible light, infrared light, microwaves and this type of radiation only damages cells if the intensity is high enough to cause excessive heating. Ultraviolet radiation has some features of both ionizing and non-ionizing radiation and these properties derive from ultraviolets power to alter chemical bonds, even without having quite enough energy to ionize atoms. The word radiation arises from the phenomenon of waves radiating from a source and this aspect leads to a system of measurements and physical units that are applicable to all types of radiation. This law does not apply close to a source of radiation or for focused beams. Radiation with sufficiently high energy can ionize atoms, that is to say it can knock electrons off atoms, ionization occurs when an electron is stripped from an electron shell of the atom, which leaves the atom with a net positive charge. Because living cells and, more importantly, the DNA in those cells can be damaged by this ionization, thus ionizing radiation is somewhat artificially separated from particle radiation and electromagnetic radiation, simply due to its great potential for biological damage. While an individual cell is made of trillions of atoms, only a fraction of those will be ionized at low to moderate radiation powers. If the source of the radiation is a radioactive material or a nuclear process such as fission or fusion. Particle radiation is subatomic particles accelerated to relativistic speeds by nuclear reactions, because of their momenta they are quite capable of knocking out electrons and ionizing materials, but since most have an electrical charge, they dont have the penetrating power of ionizing radiation. The exception is neutron particles, see below, there are several different kinds of these particles, but the majority are alpha particles, beta particles, neutrons, and protons. Roughly speaking, photons and particles with energies above about 10 electron volts are ionizing, particle radiation from radioactive material or cosmic rays almost invariably carries enough energy to be ionizing. The radiation is invisible and not directly detectable by human senses, as a result, in some cases, it may lead to secondary emission of visible light upon its interaction with matter, as in the case of Cherenkov radiation and radio-luminescence. Ionizing radiation has many uses in medicine, research and construction. Ultraviolet, of wavelengths from 10 nm to 125 nm, ionizes air molecules, causing it to be absorbed by air
8.
Distillation
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Distillation is a process of separating the component or substances from a liquid mixture by selective evaporation and condensation. Distillation may result in complete separation, or it may be a partial separation that increases the concentration of selected components of the mixture. In either case the process exploits differences in the volatility of the mixtures components, in industrial chemistry, distillation is a unit operation of practically universal importance, but it is a physical separation process and not a chemical reaction. For example, In the fossil fuel industry distillation is a class of operation in obtaining materials from crude oil for fuels. Distillation permits separation of air into its components — notably oxygen, nitrogen, Distillation of fermented products produces distilled beverages with a high alcohol content, or separates out other fermentation products of commercial value. An installation for distillation, especially of alcohol, is a distillery, the distillation equipment is a still. Distillation is an old method of artificial desalination. Aristotle wrote about the process in his Meteorologica and even that ordinary wine possesses a kind of exhalation, later evidence of distillation comes from Greek alchemists working in Alexandria in the 1st century AD. Distilled water has been known since at least c,200, when Alexander of Aphrodisias described the process. Work on distilling other liquids continued in early Byzantine Egypt under the Greek-Egyptian Zosimus of Panopolis, Distillation in China could have begun during the Eastern Han Dynasty, but archaeological evidence indicates that actual distillation of beverages began in the Jin and Southern Song dynasties. A still was found in a site in Qinglong, Hebei province dating to the 12th century. Distilled beverages were more common during the Yuan dynasty, arabs learned the process from the Alexandrians and used it extensively in their chemical experiments. Clear evidence of the distillation of alcohol comes from the School of Salerno in the 12th century, fractional distillation was developed by Tadeo Alderotti in the 13th century. In 1500, German alchemist Hieronymus Braunschweig published Liber de arte destillandi the first book dedicated to the subject of distillation. In 1651, John French published The Art of Distillation the first major English compendium of practice and this includes diagrams with people in them showing the industrial rather than bench scale of the operation. As alchemy evolved into the science of chemistry, vessels called retorts became used for distillations, riveted joints were often kept tight by using various mixtures, for instance a dough made of rye flour. These alembics often featured a system around the beak, using cold water for instance. Today, the retorts and pot stills have largely supplanted by more efficient distillation methods in most industrial processes
9.
Namib
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The Namib is a coastal desert in southern Africa. The name Namib is of Nama origin and means vast place, the Namibs northernmost portion, which extends 450 kilometres from the Angola-Namibia border, is known as Moçâmedes Desert, while its southern portion approaches the neighboring Kalahari Desert. From the Atlantic coast eastward, the Namib gradually ascends in elevation, annual precipitation ranges from 2 millimetres in the most arid regions to 200 millimetres at the escarpment, making the Namib the only true desert in southern Africa. Having endured arid or semi-arid conditions for roughly 55–80 million years, the desert geology consists of sand seas near the coast, while gravel plains and scattered mountain outcrops occur further inland. The sand dunes, some of which are 300 metres high, fogs that originate offshore from the collision of the cold Benguela Current and warm air from the Hadley Cell create a fog belt that frequently envelops parts of the desert. Coastal regions can experience more than 180 days of fog a year. While this has proved a hazard to ships—more than a thousand wrecks litter the Skeleton Coast—it is a vital source of moisture for desert life. Owing to its antiquity, the Namib may be home to endemic species than any other desert in the world. Most of the wildlife is arthropods and other small animals that live on little water. Near the coast, the ocean water is rich in fishery resources and supports populations of brown fur seals and shorebirds. Further inland, the Namib-Naukluft National Park, the largest game park in Africa, supports populations of African Bush Elephants, Mountain Zebras, and other large mammals. Although the outer Namib is largely barren of vegetation, lichens and succulents are found in areas, while grasses, shrubs. A few types of trees are able to survive the extremely arid climate. The Namib Desert is one of the 500 distinct physiographic provinces of the South African Platform physiographic division and it occupies an area of around 80,950 km², stretching from the[Usiab River to the town of Lüderitz and from the Atlantic Ocean to the Namib Escarpment. It is about 1,000 miles long north to south. To the south, the Namib borders on the South African Karoo semi-desert, southern Namib comprises a vast dune sea with some of the tallest and most spectacular dunes of the world, ranging in color from pink to vivid orange. In the Sossusvlei area, several dunes exceed 300 meters in height, the complexity and regularity of dune patterns in its dune sea have attracted the attention of geologists for decades, but it remains poorly understood. Moving north from Sossusvlei, the sand gradually gives way to a desert that extends all the way from Sossusvlei to the Swakop river
10.
Phytophthora infestans
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Phytophthora infestans is an oomycete that causes the serious potato disease known as late blight or potato blight. Late blight was a culprit in the 1840s European, the 1845 Irish. The organism can also infect tomatoes and some members of the Solanaceae. At first, the spots are gray-green and water-soaked, but they soon enlarge and turn brown and firm. The genus name Phytophthora comes from the Greek φυτό-, meaning plant, plus the Greek φθορά, meaning destruction, the species name infestans is the present participle of the Latin verb infestare, meaning attacking, destroying. The asexual life cycle of Phytophthora infestans is characterized by alternating phases of growth, sporulation, sporangia germination. There is also a cycle, which occurs when isolates of opposite mating type meet. Hormonal communication triggers the formation of the spores, called oospores. The different types of spores play major roles in the dissemination, sporangia are spread by wind or water and enable the movement of P. infestans between different host plants. The zoospores released from sporangia are biflagellated and chemotactic, allowing movement of P. infestans on water films found on leaves or soils. Both sporangia and zoospores are short-lived, in contrast to oospores which can persist in a form for many years. Under ideal conditions, the cycle can be completed on potato or tomato foliage in about five days. Sporangia develop on the leaves, spreading through the crop when temperatures are above 10 °C, rain can wash spores into the soil where they infect young tubers, and the spores can also travel long distances on the wind. The early stages of blight are easily missed, symptoms include the appearance of dark blotches on leaf tips and plant stems. White mould will appear under the leaves in humid conditions and the plant may quickly collapse. Infected tubers develop grey or dark patches that are reddish brown beneath the skin, seemingly healthy tubers may rot later when in store. P. infestans survives poorly in nature apart from its plant hosts, under most conditions, the hyphae and asexual sporangia can survive for only brief periods in plant debris or soil, and are generally killed off during frosts or very warm weather. The exceptions involve oospores, and hyphae present within tubers, the persistence of viable pathogen within tubers, such as those that are left in the ground after the previous years harvest or left in cull piles is a major problem in disease management
11.
Atmospheric pressure
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Atmospheric pressure, sometimes also called barometric pressure, is the pressure exerted by the weight of air in the atmosphere of Earth. In most circumstances atmospheric pressure is approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. On average, a column of air one square centimetre in cross-section, measured from sea level to the top of the atmosphere, has a mass of about 1.03 kilograms and that force is a pressure of 10.1 N/cm2 or 101 kN/m2. A column 1 square inch in cross-section would have a weight of about 14.7 lb or about 65.4 N and it is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition. The standard atmosphere is a unit of pressure defined as 101325 Pa, the mean sea level pressure is the average atmospheric pressure at sea level. This is the pressure normally given in weather reports on radio, television. When barometers in the home are set to match the weather reports, they measure pressure adjusted to sea level. The altimeter setting in aviation, is an atmospheric pressure adjustment, average sea-level pressure is 1013.25 mbar. In aviation weather reports, QNH is transmitted around the world in millibars or hectopascals, except in the United States, Canada, however, in Canadas public weather reports, sea level pressure is instead reported in kilopascals. The highest sea-level pressure on Earth occurs in Siberia, where the Siberian High often attains a sea-level pressure above 1050 mbar, the lowest measurable sea-level pressure is found at the centers of tropical cyclones and tornadoes, with a record low of 870 mbar. Pressure varies smoothly from the Earths surface to the top of the mesosphere, although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. As altitude increases, atmospheric pressure decreases, one can calculate the atmospheric pressure at a given altitude. Temperature and humidity affect the atmospheric pressure, and it is necessary to know these to compute an accurate figure. The graph at right was developed for a temperature of 15 °C, at low altitudes above the sea level, the pressure decreases by about 1.2 kPa for every 100 meters. See pressure system for the effects of air pressure variations on weather, Atmospheric pressure shows a diurnal or semidiurnal cycle caused by global atmospheric tides. This effect is strongest in tropical zones, with an amplitude of a few millibars and these variations have two superimposed cycles, a circadian cycle and semi-circadian cycle. The highest adjusted-to-sea level barometric pressure recorded on Earth was 1085.7 hPa measured in Tosontsengel
