Population density is a measurement of population per unit area or unit volume. It is applied to living organisms, most of the time to humans, it is a key geographical term. In simple terms population density refers to the number of people living in an area per kilometer square. Population density is population divided by total land water volume, as appropriate. Low densities may lead to further reduced fertility; this is called the Allee effect after the scientist. Examples of the causes in low population densities include: Increased problems with locating sexual mates Increased inbreeding For humans, population density is the number of people per unit of area quoted per square kilometer or square mile; this may be calculated for a county, country, another territory or the entire world. The world's population is around 7,500,000,000 and Earth's total area is 510,000,000 square kilometers. Therefore, the worldwide human population density is around 7,500,000,000 ÷ 510,000,000 = 14.7 per km2. If only the Earth's land area of 150,000,000 km2 is taken into account human population density is 50 per km2.
This includes all continental and island land area, including Antarctica. If Antarctica is excluded population density rises to over 55 people per km2. However, over half of the Earth's land mass consists of areas inhospitable to human habitation, such as deserts and high mountains, population tends to cluster around seaports and fresh-water sources. Thus, this number by itself does not give any helpful measurement of human population density. Several of the most densely populated territories in the world are city-states and dependencies; these territories have a small area and a high urbanization level, with an economically specialized city population drawing on rural resources outside the area, illustrating the difference between high population density and overpopulation The potential to maintain the agricultural aspects of deserts is limited as there is not enough precipitation to support a sustainable land. The population in these areas are low. Therefore, cities in the Middle East, such as Dubai, have been increasing in population and infrastructure growth at a fast pace.
Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources. Most of the most densely populated cities are in Southeast Asia, though Cairo and Lagos in Africa fall into this category. City population and area are, however dependent on the definition of "urban area" used: densities are invariably higher for the central city area than when suburban settlements and the intervening rural areas are included, as in the areas of agglomeration or metropolitan area, the latter sometimes including neighboring cities. For instance, Milwaukee has a greater population density when just the inner city is measured, the surrounding suburbs excluded. In comparison, based on a world population of seven billion, the world's inhabitants, as a loose crowd taking up ten square feet per person, would occupy a space a little larger than Delaware's land area; the Gaza Strip has a population density of 5,046 pop/km.
Although arithmetic density is the most common way of measuring population density, several other methods have been developed to provide a more accurate measure of population density over a specific area. Arithmetic density: The total number of people / area of land Physiological density: The total population / area of arable land Agricultural density: The total rural population / area of arable land Residential density: The number of people living in an urban area / area of residential land Urban density: The number of people inhabiting an urban area / total area of urban land Ecological optimum: The density of population that can be supported by the natural resources Demography Human geography Idealized population Optimum population Population genetics Population health Population momentum Population pyramid Rural transport problem Small population size Distance sampling List of population concern organizations List of countries by population density List of cities by population density List of city districts by population density List of English districts by population density List of European cities proper by population density List of United States cities by population density List of islands by population density List of U.
S. states by population density List of Australian suburbs by population density Selected Current and Historic City, Ward & Neighborhood Density Duncan Smith / UCL Centre for Advanced Spatial Analysis. "World Population Density". Exploratory map shows data from the Global Human Settlement Layer produced by the European Commission JRC and the CIESIN Columbia University
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, sleet, snow and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and "precipitates", thus and mist are not precipitation but suspensions, because the water vapor does not condense sufficiently to precipitate. Two processes acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called "showers."Moisture, lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is active when freezing rain occurs. A stationary front is present near the area of freezing rain and serves as the foci for forcing and rising air.
Provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. The cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects. Where warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones. Lake-effect snowfall can be locally heavy. Thundersnow is possible within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. Most precipitation is caused by convection; the movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.
Precipitation is a major component of the water cycle, is responsible for depositing the fresh water on the planet. 505,000 cubic kilometres of water falls as precipitation each year. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres, but over land it is only 715 millimetres. Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Precipitation may occur on other celestial bodies, e.g. when it gets cold, Mars has precipitation which most takes the form of frost, rather than rain or snow. Precipitation is a major component of the water cycle, is responsible for depositing most of the fresh water on the planet. 505,000 km3 of water falls as precipitation each year, 398,000 km3 of it over the oceans. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres. Mechanisms of producing precipitation include convective and orographic rainfall.
Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation, while stratiform processes involve weaker upward motions and less intense precipitation. Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice. Mixtures of different types of precipitation, including types in different categories, can fall simultaneously. Liquid forms of precipitation include drizzle. Rain or drizzle that freezes on contact within a subfreezing air mass is called "freezing rain" or "freezing drizzle". Frozen forms of precipitation include snow, ice needles, ice pellets and graupel; the dew point is the temperature to which a parcel must be cooled in order to become saturated, condenses to water. Water vapor begins to condense on condensation nuclei such as dust and salt in order to form clouds. An elevated portion of a frontal zone forces broad areas of lift, which form clouds decks such as altostratus or cirrostratus.
Stratus is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. It can form due to the lifting of advection fog during breezy conditions. There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling, evaporative cooling. Adiabatic cooling occurs when air expands; the air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain. Conductive cooling occurs when the air comes into contact with a colder surface by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation, either by the air or by the surface underneath. Evaporative cooling occurs when moisture is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature, or until it reaches saturation; the main ways water vapor is added to the air are: wind convergence into areas of upward motion, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, water bodies or wet lan
Shioya is a town located in Tochigi Prefecture, Japan. As of May 2015, the town had an estimated population of 11,542, a population density of 65.5 persons per km2. Its total area is 176.06 km2. Shioya is located in central Tochigi Prefecture. Tochigi Prefecture Utsunomiya Sakura Nasushiobara Yaita Nikkō The villages of Tamanyu and Omiya were created within Shioya District of Tochigi Prefecture on April 1, 1889 with the creation of the municipalities system after the Meiji Restoration; the three villages merged on March 1957 to create the village of Shioya. Shioya was elevated to town status on February 11, 1965; the economy of Shioya is dependent on agriculture, but is a bedroom community for the nearby cities of Utsunomiya and Nikkō. Shioya has one middle school, and two high schools. Shioya is not served by any train stations. Japan National Route 461 Shojinzawa Yusui – one of the 100 famous springs of Japan Shioya Onsen Media related to Shioya, Tochigi at Wikimedia Commons Official Website
Nikkō Tōshō-gū is a Tōshō-gū Shinto shrine located in Nikkō, Tochigi Prefecture, Japan. Together with Futarasan Shrine and Rinnō-ji, it forms the Shrines and Temples of Nikkō UNESCO World Heritage Site, with 42 structures of the shrine included in the nomination. Five of them are designated as National Treasures of Japan, three more as Important Cultural Properties. Tōshō-gū is dedicated to the founder of the Tokugawa shogunate, it was built in 1617, during the Edo period, while Ieyasu's son Hidetada was shōgun. It was enlarged during the time of Iemitsu. Ieyasu is enshrined there, where his remains are entombed; this shrine was built by Tokugawa retainer Tōdō Takatora. During the Edo period, the Tokugawa shogunate carried out stately processions from Edo to the Nikkō Tōshō-gū along the Nikkō Kaidō; the shrine's annual spring and autumn festivals reenact these occasions, are known as "processions of a thousand warriors". Part of the beauty is the row of majestic trees lining the roadway, termed the Cedar Avenue of Nikkō.
Five structures at Nikkō Tōshō-gū are categorized as National Treasures of Japan, three more as Important Cultural Properties. Additionally, two swords in the possession of the shrine are National Treasures, numerous other objects are Important Cultural Properties. Famous buildings at the Tōshō-gū include the richly decorated Yōmeimon, a gate, known as "higurashi-no-mon"; the latter name means that one could look at it until sundown, not tire of seeing it. Carvings in deep relief, painted in rich colors, decorate the surface of the structure; the next gate is the karamon decorated with white ornaments. Located nearby is a woodcarving of a sleepy cat, "Nemuri-neko", attributed to Hidari Jingorō; the stable of the shrine's sacred horses bears a carving of the three wise monkeys, who hear and see no evil, a traditional symbol in Chinese and Japanese culture. The original five-storey pagoda was donated by a daimyō in 1650, but it was burned down during a fire, was rebuilt in 1818; each storey represents an element–earth, fire and aether –in ascending order.
Inside the pagoda, a central shinbashira pillar hangs from chains to minimize damage from earthquakes. Hundreds of stone steps lead through the cryptomeria forest up to the grave of Ieyasu. A torii at the top bears calligraphy attributed to Emperor Go-Mizunoo. A bronze urn contains the remains of Tokugawa Ieyasu. In 2008 Yuri Kawasaki became the first female Shinto priest to serve at Nikkō Tōshō-gū. List of National Treasures of Japan List of National Treasures of Japan Shinbashira, the central wooden column freely suspended Official website Official website UNESCO website - Shrines and Temples of Nikko Accessibility of Nikkō Tōshō-gū
Autumn leaf color
Autumn leaf color is a phenomenon that affects the normal green leaves of many deciduous trees and shrubs by which they take on, during a few weeks in the autumn season, various shades of red, purple, orange, magenta and brown. The phenomenon is called autumn colours or autumn foliage in British English and fall colors, fall foliage or foliage in American English. In some areas of Canada and the United States, "leaf peeping" tourism is a major contribution to economic activity; this tourist activity occurs between the beginning of color changes and the onset of leaf fall around September and October in the Northern Hemisphere and April to May in the Southern Hemisphere. A green leaf is green because of the presence of a pigment known as chlorophyll, inside an organelle called a chloroplast; when they are abundant in the leaf's cells, as they are during the growing season, the chlorophyll's green color dominates and masks out the colors of any other pigments that may be present in the leaf. Thus, the leaves of summer are characteristically green.
Chlorophyll has a vital function: it captures solar rays and uses the resulting energy in the manufacture of the plant's food — simple sugars which are produced from water and carbon dioxide. These sugars are the basis of the plant's nourishment — the sole source of the carbohydrates needed for growth and development. In their food-manufacturing process, the chlorophylls break down, thus are being continually "used up". During the growing season, the plant replenishes the chlorophyll so that the supply remains high and the leaves stay green. In late summer, as daylight hours shorten and temperatures cool, the veins that carry fluids into and out of the leaf are closed off as a layer of special cork cells forms at the base of each leaf; as this cork layer develops and mineral intake into the leaf is reduced at first, more rapidly. During this time, the chlorophyll begins to decrease; the veins are still green after the tissues between them have completely changed color. Much chlorophyll is in the most abundant membrane protein on earth.
LHC II captures light in photosynthesis. It is located in the thylakoid membrane of the chloroplast and it is composed of an apoprotein along with several ligands, the most important of which are chlorophylls a and b. In the fall, this complex is broken down. Chlorophyll degradation is thought to occur first. Recent research suggests that the beginning of chlorophyll degradation is catalyzed by chlorophyll b reductase, which reduces chlorophyll b to 7‑hydroxymethyl chlorophyll a, reduced to chlorophyll a; this is believed to destabilize the complex. An important enzyme in the breakdown of the apoprotein is FtsH6, which belongs to the FtsH family of proteases. Chlorophylls degrade into colorless tetrapyrroles known as nonfluorescent chlorophyll catabolites; as the chlorophylls degrade, the hidden pigments of yellow xanthophylls and orange beta-carotene are revealed. These pigments are present throughout the year, but the red pigments, the anthocyanins, are synthesized de novo once half of chlorophyll has been degraded.
The amino acids released from degradation of light harvesting complexes are stored all winter in the tree's roots, branches and trunk until next spring, when they are recycled to releaf the tree. Carotenoids are present in leaves the whole year round, but their orange-yellow colors are masked by green chlorophyll; as autumn approaches, certain influences both inside and outside the plant cause the chlorophylls to be replaced at a slower rate than they are being used up. During this period, with the total supply of chlorophylls dwindling, the "masking" effect fades away. Other pigments that have been present in the cells all during the leaf's life begin to show through; these are carotenoids and they provide colorations of yellow, brown and the many hues in between. The carotenoids occur, along with the chlorophyll pigments, in tiny structures called plastids, within the cells of leaves. Sometimes, they are in such abundance in the leaf that they give a plant a yellow-green color during the summer.
However, they become prominent for the first time in autumn, when the leaves begin to lose their chlorophyll. Carotenoids are common in many living things, giving characteristic color to carrots, corn and daffodils, as well as egg yolks, rutabagas and bananas, their brilliant yellows and oranges tint the leaves of such hardwood species as hickories, maple, yellow poplar, birch, black cherry, cottonwood and alder. Carotenoids are the dominant pigment in coloration of about 15-30% of tree species; the reds, the purples, their blended combinations that decorate autumn foliage come from another group of pigments in the cells called anthocyanins. Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are produced towards the end of summer, they develop in late summer in the sap of the cells of the leaf, this development is the result of complex interactions of many influences—both inside and outside the plant. Their formation depends on the breakdown of sugars in the presence of bright light as the level of phosphate in the leaf is reduced.
During the summer growing season, phosphate is at a high level. It has a vital role in the breakdown of the sugars manufactured by chlorophyll, but in the fall, along with the other chemicals and nutrients, moves out of the leaf into the stem of the plant; when this happens, the sugar-breakdown process changes, lea
Minamiaizu is a town located in Fukushima Prefecture, Japan. As of 1 December 2018, the town had an estimated population of 15,700 in 6,708 households, a population density of 18.0 persons per km². The total area of the town was 886.52 square kilometres. MInamiaizu is located in the mountainous southern portion of the Aizu region of Fukushima Prefecture, bordered Tochigi Prefecture to the south. Mountains: Onsabi Mountains, Mount Nanatsugadake Rivers: Okawa, Ina River Fukushima Prefecture Shimogō Hinoemata Tadami Shōwa Tochigi Prefecture Nasushiobara, Tochigi Nikkō, Tochigi Minamiaizu has a Humid continental climate characterized by warm summers and cold winters with heavy snowfall; the average annual temperature in Minamiaizu is 8.8 °C. The average annual rainfall is 1642 mm with September as the wettest month; the temperatures are highest on average in August, at around 24.8 °C, lowest in January, at around -3.4 °C. Per Japanese census data, the population of Minamiaizu has declined over the past 40 years.
The area of present-day Minamiaizu was part of ancient Mutsu Province and formed part of the holdings of Aizu Domain during the Edo period. After the Meiji Restoration, it was organized as part of Minamiaizu District in Fukushima Prefecture. With the establishment of the modern municipalities system on April 1, 1889, the town of Tajima and the villages of Ina, Nangō, Tateiwa were established; these four municipalities merged on March 2006 to form the town of Minamiaizu. The economy of Minamiaizu is agricultural. Rice and asparagus are the main crops; the town has seven public elementary schools and four public junior high school operated by the town government. The town has two public high schools operated by the Fukushima Prefectural Board of Education. Fukushima Prefectural Tajima High School Fukushima Prefectural Minamiaizu High School Aizu Railway – Aizu Line Aizu-Nagano - Tajimakōkōmae - Aizu-Tajima - Nakaarai - Aizu-Arakai - Aizu-Sanson-Dōjō - Nanatsugatake-Tozanguchi - Aizukōgen-Ozeguchi■ Yagan Railway – Aizu Kinugawa Line Aizukōgen-Ozeguchi National Route 121 National Route 289 National Route 352 National Route 400 National Route 401 Aizu-Tajima Gionsai festival Okuaizu Museum Komado Wetlands Tashiroyama Wetlands Yunohana Onsen Hosoi Residence Museum Maezawa Magariya Village Kozo Watanabe - politician Media related to Minamiaizu, Fukushima at Wikimedia Commons Official Website
Concrete Portland cement concrete, is a composite material composed of fine and coarse aggregate bonded together with a fluid cement that hardens over time—most a lime-based cement binder, such as Portland cement, but sometimes with other hydraulic cements, such as a calcium aluminate cement. It is distinguished from other, non-cementitious types of concrete all binding some form of aggregate together, including asphalt concrete with a bitumen binder, used for road surfaces, polymer concretes that use polymers as a binder; when aggregate is mixed together with dry Portland cement and water, the mixture forms a fluid slurry, poured and molded into shape. The cement reacts chemically with the water and other ingredients to form a hard matrix that binds the materials together into a durable stone-like material that has many uses. Additives are included in the mixture to improve the physical properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials embedded to provide tensile strength, yielding reinforced concrete.
Famous concrete structures include the Panama Canal and the Roman Pantheon. The earliest large-scale users of concrete technology were the ancient Romans, concrete was used in the Roman Empire; the Colosseum in Rome was built of concrete, the concrete dome of the Pantheon is the world's largest unreinforced concrete dome. Today, large concrete structures are made with reinforced concrete. After the Roman Empire collapsed, use of concrete became rare until the technology was redeveloped in the mid-18th century. Worldwide, concrete has overtaken steel in tonnage of material used; the word concrete comes from the Latin word "concretus", the perfect passive participle of "concrescere", from "con-" and "crescere". Small-scale production of concrete-like materials was pioneered by the Nabatean traders who occupied and controlled a series of oases and developed a small empire in the regions of southern Syria and northern Jordan from the 4th century BC, they discovered the advantages of hydraulic lime, with some self-cementing properties, by 700 BC.
They built kilns to supply mortar for the construction of rubble-wall houses, concrete floors, underground waterproof cisterns. They kept the cisterns secret; some of these structures survive to this day. In the Ancient Egyptian and Roman eras, builders discovered that adding volcanic ash to the mix allowed it to set underwater. German archaeologist Heinrich Schliemann found concrete floors, which were made of lime and pebbles, in the royal palace of Tiryns, which dates to 1400–1200 BC. Lime mortars were used in Greece and Cyprus in 800 BC; the Assyrian Jerwan Aqueduct made use of waterproof concrete. Concrete was used for construction in many ancient structures; the Romans used concrete extensively from 300 BC to a span of more than seven hundred years. During the Roman Empire, Roman concrete was made from quicklime, pozzolana and an aggregate of pumice, its widespread use in many Roman structures, a key event in the history of architecture termed the Roman Architectural Revolution, freed Roman construction from the restrictions of stone and brick materials.
It enabled revolutionary new designs in terms of both structural dimension. Concrete, as the Romans knew it, was a revolutionary material. Laid in the shape of arches and domes, it hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick. Modern tests show that opus caementicium had as much compressive strength as modern Portland-cement concrete. However, due to the absence of reinforcement, its tensile strength was far lower than modern reinforced concrete, its mode of application was different: Modern structural concrete differs from Roman concrete in two important details. First, its mix consistency is fluid and homogeneous, allowing it to be poured into forms rather than requiring hand-layering together with the placement of aggregate, which, in Roman practice consisted of rubble. Second, integral reinforcing steel gives modern concrete assemblies great strength in tension, whereas Roman concrete could depend only upon the strength of the concrete bonding to resist tension.
The long-term durability of Roman concrete structures has been found to be due to its use of pyroclastic rock and ash, whereby crystallization of strätlingite and the coalescence of calcium–aluminum-silicate–hydrate cementing binder helped give the concrete a greater degree of fracture resistance in seismically active environments. Roman concrete is more resistant to erosion by seawater than modern concrete; the widespread use of concrete in many Roman structures ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges, such as the magnificent Pont du Gard in southern France, have masonry cladding on a concrete core, as does the dome of the Pantheon. After the Roman Empire, the use of burned lime and pozzolana was reduced until the technique was all but forgotten between 500 and the 14th century. From the 14th century to the mid-18th century, the use of cement returned; the Canal du Midi was built using concrete in 1670.
The greatest step forward in the modern use