China, officially the Peoples Republic of China, is a unitary sovereign state in East Asia and the worlds most populous country, with a population of over 1.381 billion. The state is governed by the Communist Party of China and its capital is Beijing, the countrys major urban areas include Shanghai, Beijing, Shenzhen and Hong Kong. China is a power and a major regional power within Asia. Chinas landscape is vast and diverse, ranging from forest steppes, the Himalaya, Karakoram and Tian Shan mountain ranges separate China from much of South and Central Asia. The Yangtze and Yellow Rivers, the third and sixth longest in the world, Chinas coastline along the Pacific Ocean is 14,500 kilometers long and is bounded by the Bohai, East China and South China seas. China emerged as one of the worlds earliest civilizations in the basin of the Yellow River in the North China Plain. For millennia, Chinas political system was based on hereditary monarchies known as dynasties, in 1912, the Republic of China replaced the last dynasty and ruled the Chinese mainland until 1949, when it was defeated by the communist Peoples Liberation Army in the Chinese Civil War.
The Communist Party established the Peoples Republic of China in Beijing on 1 October 1949, both the ROC and PRC continue to claim to be the legitimate government of all China, though the latter has more recognition in the world and controls more territory. China had the largest economy in the world for much of the last two years, during which it has seen cycles of prosperity and decline. Since the introduction of reforms in 1978, China has become one of the worlds fastest-growing major economies. As of 2016, it is the worlds second-largest economy by nominal GDP, China is the worlds largest exporter and second-largest importer of goods. China is a nuclear weapons state and has the worlds largest standing army. The PRC is a member of the United Nations, as it replaced the ROC as a permanent member of the U. N. Security Council in 1971. China is a member of numerous formal and informal multilateral organizations, including the WTO, APEC, BRICS, the Shanghai Cooperation Organization, the BCIM, the English name China is first attested in Richard Edens 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa.
The demonym, that is, the name for the people, Portuguese China is thought to derive from Persian Chīn, and perhaps ultimately from Sanskrit Cīna. Cīna was first used in early Hindu scripture, including the Mahābhārata, there are, other suggestions for the derivation of China. The official name of the state is the Peoples Republic of China. The shorter form is China Zhōngguó, from zhōng and guó and it was applied to the area around Luoyi during the Eastern Zhou and to Chinas Central Plain before being used as an occasional synonym for the state under the Qing
Soil is a mixture of minerals, organic matter, gases and countless organisms that together support life on Earth. Soil is called the Skin of the Earth and interfaces with the lithosphere, the hydrosphere, the atmosphere, the term pedolith, used commonly to refer to the soil, literally translates ground stone. Soil consists of a phase of minerals and organic matter, as well as a porous phase that holds gases. Accordingly, soils are often treated as a system of solids, liquids. Soil is a product of the influence of climate, organisms, Soil continually undergoes development by way of numerous physical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness soil has been considered as an ecosystem by soil ecologists. Most soils have a dry bulk density between 1.1 and 1.6 g/cm3, while the particle density is much higher. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, Soil science has two basic branches of study and pedology.
Edaphology is concerned with the influence of soils on living things, pedology is focused on the formation and classification of soils in their natural environment. In engineering terms, soil is referred to as regolith, or loose material that lies above the solid geology. Soil is commonly referred to as earth or dirt, technically, as soil resources serve as a basis for food security, the international community advocates its sustainable and responsible use through different types of soil governance. Soil is a component of the Earths ecosystem. The worlds ecosystems are impacted in far-reaching ways by the carried out in the soil, from ozone depletion and global warming, to rainforest destruction. Following the atmosphere, the soil is the next largest carbon reservoir on Earth, as the planet warms, soils will add carbon dioxide to the atmosphere due to its increased biological activity at higher temperatures. Thus, soil carbon losses likely have a positive feedback response to global warming.
Since soil has a range of available niches and habitats. A gram of soil can contain billions of organisms, belonging to thousands of species, mostly microbial, Soil has a mean prokaryotic density of roughly 108 organisms per gram, whereas the ocean has no more than 107 procaryotic organisms per milliliter of seawater. Since plant roots need oxygen, ventilation is an important characteristic of soil and this ventilation can be accomplished via networks of interconnected soil pores, which absorb and hold rainwater making it readily available for plant uptake
In biology, an organism is any contiguous living system, such as an animal, fungus, archaeon, or bacterium. All known types of organisms are capable of some degree of response to stimuli, reproduction and development and homeostasis. An organism consists of one or more cells, when it has one cell it is known as an organism. Most unicellular organisms are of microscopic scale and are thus described as microorganisms. Humans are multicellular organisms composed of trillions of cells grouped into specialized tissues. An organism may be either a prokaryote or a eukaryote, prokaryotes are represented by two separate domains—bacteria and archaea. Eukaryotic organisms are characterized by the presence of a cell nucleus. Fungi and plants are examples of kingdoms of organisms within the eukaryotes, estimates on the number of Earths current species range from 10 million to 14 million, of which only about 1.2 million have been documented. More than 99% of all species, amounting to five billion species. In 2016, a set of 355 genes from the last universal ancestor of all living organisms living was identified.
The term organism first appeared in the English language in 1703 and it is directly related to the term organization. There is a tradition of defining organisms as self-organizing beings. An organism may be defined as an assembly of molecules functioning as a more or less stable whole that exhibits the properties of life. Dictionary definitions can be broad, using such as any living structure, such as a plant, fungus or bacterium, capable of growth. Many definitions exclude viruses and possible man-made non-organic life forms, as viruses are dependent on the machinery of a host cell for reproduction. A superorganism is an organism consisting of individuals working together as a single functional or social unit. There has been controversy about the best way to define the organism, several contributions are responses to the suggestion that the category of organism may well not be adequate in biology. Viruses are not typically considered to be organisms because they are incapable of autonomous reproduction and this controversy is problematic because some cellular organisms are incapable of independent survival and live as obligatory intracellular parasites
Africa is the worlds second-largest and second-most-populous continent. At about 30.3 million km² including adjacent islands, it covers 6% of Earths total surface area and 20.4 % of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the human population. The continent includes Madagascar and various archipelagos and it contains 54 fully recognized sovereign states, nine territories and two de facto independent states with limited or no recognition. Africas population is the youngest amongst all the continents, the age in 2012 was 19.7. Algeria is Africas largest country by area, and Nigeria by population, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens found in Ethiopia being dated to circa 200,000 years ago. Africa straddles the equator and encompasses numerous climate areas, it is the continent to stretch from the northern temperate to southern temperate zones. Africa hosts a diversity of ethnicities and languages. In the late 19th century European countries colonized most of Africa, Africa varies greatly with regard to environments, historical ties and government systems.
However, most present states in Africa originate from a process of decolonization in the 20th century, afri was a Latin name used to refer to the inhabitants of Africa, which in its widest sense referred to all lands south of the Mediterranean. This name seems to have referred to a native Libyan tribe. The name is connected with Hebrew or Phoenician ʿafar dust. The same word may be found in the name of the Banu Ifran from Algeria and Tripolitania, under Roman rule, Carthage became the capital of the province of Africa Proconsularis, which included the coastal part of modern Libya. The Latin suffix -ica can sometimes be used to denote a land, the Muslim kingdom of Ifriqiya, modern-day Tunisia, preserved a form of the name. According to the Romans, Africa lay to the west of Egypt, while Asia was used to refer to Anatolia, as Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge. 25,4, whose descendants, he claimed, had invaded Libya, isidore of Seville in Etymologiae XIV.5.2.
Suggests Africa comes from the Latin aprica, meaning sunny, massey, in 1881, stated that Africa is derived from the Egyptian af-rui-ka, meaning to turn toward the opening of the Ka. The Ka is the double of every person and the opening of the Ka refers to a womb or birthplace
Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animals behaviour rather than morphology. The name is derived from the Greek words κόπρος and λίθος and they were first described by William Buckland in 1829. Prior to this they were known as fir cones and bezoar stones. They serve a purpose in paleontology because they provide direct evidence of the predation. Coprolites may range in size from a few millimetres to over 60 centimetres, distinct from paleofaeces, are fossilized animal dung. Like other fossils, coprolites have had much of their original composition replaced by mineral deposits such as silicates, in the same context, there are the urolites, erosions caused by evacuation of liquid wastes and nonliquid urinary secretions. The fossil hunter Mary Anning had noticed that bezoar stones were found in the abdominal region of ichthyosaur skeletons found in the Lias formation at Lyme Regis. She noted that if such stones were broken open they often contained fossilized fish bones and scales as well as sometimes bones from smaller ichthyosaurs.
It was these observations by Anning that led the geologist William Buckland to propose in 1829 that the stones were fossilized feces and named them coprolites. In one example these fossils can be analyzed for certain minerals that are known to exist in trace amounts in certain species of plant that can still be detected millions of years later. In another example, the existence of proteins in coprolites can be used to pinpoint the existence of cannibalistic behavior in an ancient culture. The recognition of coprolites is aided by their structural patterns, such as spiral or annular markings, by their content, such as undigested food fragments, the smallest coprolites are often difficult to distinguish from inorganic pellets or from eggs. Most coprolites are composed chiefly of calcium phosphate, along with quantities of organic matter. By analyzing coprolites, it is possible to infer the diet of the animal which produced them, coprolites have been recorded in deposits ranging in age from the Cambrian period to recent times and are found worldwide.
Some of them are useful as index fossils, such as Favreina from the Jurassic period of Haute-Savoie in France, some marine deposits contain a high proportion of fecal remains. However, animal excrement is easily fragmented and destroyed, so usually has little chance of becoming fossilized, realising their potential as a source of available phosphate once they had been treated with sulphuric acid, he patented an extraction process and set about finding new sources. Very soon, coprolites were being mined on a scale for use as fertiliser due to their high phosphate content. The major area of extraction occurred over the east of England, centred on Cambridgeshire, there is a Coprolite Street near Ipswich docks where the Fisons works once stood
Rice is the seed of the grass species Oryza sativa or Oryza glaberrima. As a cereal grain, it is the most widely consumed staple food for a part of the worlds human population. It is the agricultural commodity with the third-highest worldwide production, after sugarcane and maize, wild rice, from which the crop was developed, may have its native range in Australia. Chinese legends attribute the domestication of rice to Shennong, the emperor of China. Genetic evidence has shown that rice originates from a single domestication 8, archaeological evidence had suggested that rice was domesticated in the Yangtze River valley region in China. From East Asia, rice was spread to Southeast and South Asia, Rice was introduced to Europe through Western Asia, and to the Americas through European colonization. There are many varieties of rice and culinary preferences tend to vary regionally, in some areas such as the Far East or Spain, there is a preference for softer and stickier varieties. Rice, a monocot, is grown as an annual plant, although in tropical areas it can survive as a perennial.
The rice plant can grow to 1–1.8 m tall, occasionally more depending on the variety and it has long, slender leaves 50–100 cm long and 2–2.5 cm broad. The small wind-pollinated flowers are produced in a branched arching to pendulous inflorescence 30–50 cm long, the edible seed is a grain 5–12 mm long and 2–3 mm thick. Rice cultivation is well-suited to countries and regions with low costs and high rainfall, as it is labor-intensive to cultivate. However, rice can be grown practically anywhere, even on a hill or mountain area with the use of water-controlling terrace systems. Although its parent species are native to Asia and certain parts of Africa, centuries of trade, the traditional method for cultivating rice is flooding the fields while, or after, setting the young seedlings. The name wild rice is used for species of the genera Zizania and Porteresia. The Greek word is the source of all European words, the origin of the Greek word is unclear. It is sometimes held to be from the Tamil word அரிசி, Krishnamurti disagrees with the notion that Old Tamil arici is the source of the Greek term, and proposes that it was borrowed from descendants of Proto-Dravidian *wariñci instead.
The varieties of rice are typically classified as long-, medium-, the grains of long-grain rice tend to remain intact after cooking, medium-grain rice becomes more sticky. Medium-grain rice is used for dishes, for risotto in Italy
Poaceae or Gramineae is a large and nearly ubiquitous family of monocotyledonous flowering plants known as grasses. Poaceae includes the cereal grasses and the grasses of natural grassland and cultivated lawns, Grasses have stems that are hollow except at the nodes and narrow alternate leaves borne in two ranks. The lower part of each leaf encloses the stem, forming a leaf-sheath, with ca 780 genera and around 12,000 species, Poaceae are the fifth-largest plant family, following the Asteraceae, Orchidaceae and Rubiaceae. Grasslands such as savannah and prairie grasses are dominant are estimated to constitute 40. 5% of the land area of the Earth, excluding Greenland. Grasses are an important part of the vegetation in many habitats, including wetlands, forests. Though commonly called grasses, seagrasses and sedges fall outside this family, the rushes and sedges are related to the Poaceae, being members of the order Poales, but the seagrasses are members of order Alismatales. The name Poaceae was given by John Hendley Barnhart in 1895, based on the tribe Poeae described in 1814 by Robert Brown, the term is derived from the Ancient Greek πόα.
Grasses include some of the most versatile plant life-forms, a cladogram shows subfamilies and approximate species numbers in brackets, Before 2005, fossil findings indicated that grasses evolved around 55 million years ago. Recent findings of grass-like phytoliths in Cretaceous dinosaur coprolites have pushed this back to 66 million years ago. In 2011, revised dating of the origins of the rice tribe Oryzeae suggested a date as early as 107 to 129 Mya, a multituberculate mammal with grass-eating adaptations seems to suggest that grasses were already around at 120 mya. This separation occurred within the short time span of about 4 million years. Grass leaves are always alternate and distichous, and have parallel veins. Each leaf is differentiated into a lower sheath hugging the stem, the leaf blades of many grasses are hardened with silica phytoliths, which discourage grazing animals, such as sword grass, are sharp enough to cut human skin. A membranous appendage or fringe of hairs called the ligule lies at the junction between sheath and blade, preventing water or insects from penetrating into the sheath, flowers of Poaceae are characteristically arranged in spikelets, each having one or more florets.
The spikelets are further grouped into panicles or spikes, the part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two bracts at the base, called glumes, followed by one or more florets, a floret consists of the flower surrounded by two bracts, one external—the lemma—and one internal—the palea. The flowers are usually hermaphroditic—maize being an important exception—and anemophilous or wind-pollinated, the perianth is reduced to two scales, called lodicules, that expand and contract to spread the lemma and palea, these are generally interpreted to be modified sepals. This complex structure can be seen in the image on the right, the fruit of grasses is a caryopsis, in which the seed coat is fused to the fruit wall
Kansas /ˈkænzəs/ is a U. S. state located in the Midwestern United States. Its capital is Topeka and its largest city is Wichita, Kansas is named after the Kansa Native American tribe, which inhabited the area. The tribes name is said to mean people of the wind or people of the south wind. For thousands of years, what is now Kansas was home to numerous, tribes in the eastern part of the state generally lived in villages along the river valleys. Tribes in the part of the state were semi-nomadic and hunted large herds of bison. When it was opened to settlement by the U. S. Thus, the area was a hotbed of violence and chaos in its early days as these forces collided. The abolitionists eventually prevailed, and on January 29,1861, after the Civil War, the population of Kansas grew rapidly when waves of immigrants turned the prairie into farmland. By 2015, Kansas was one of the most productive agricultural states, producing high yields of wheat, corn and soybeans. Kansas, which has an area of 82,278 square miles is the 15th largest state by area and is the 34th most populous of the 50 United States with a population of 2,911,641, residents of Kansas are called Kansans, officially.
Mount Sunflower is Kansass highest point at 4,041 feet, for a millennia, the land that is currently Kansas was inhabited by Native Americans. The first European to set foot in present-day Kansas was Francisco Vázquez de Coronado, in 1803, most of modern Kansas was secured by the United States as part of the Louisiana Purchase. Southwest Kansas, was still a part of Spain, from 1812 to 1821, Kansas was part of the Missouri Territory. The Santa Fe Trail traversed Kansas from 1821 to 1880, transporting manufactured goods from Missouri and silver and furs from Santa Fe, wagon ruts from the trail are still visible in the prairie today. In 1827, Fort Leavenworth became the first permanent settlement of white Americans in the future state, the Kansas–Nebraska Act became law on May 30,1854, establishing the U. S. territories of Nebraska and Kansas, and opening the area to broader settlement by whites. Kansas Territory stretched all the way to the Continental Divide and included the sites of present-day Denver, Colorado Springs and Arkansas sent settlers into Kansas all along its eastern border.
These settlers attempted to sway votes in favor of slavery, the secondary settlement of Americans in Kansas Territory were abolitionists from Massachusetts and other Free-Staters, who attempted to stop the spread of slavery from neighboring Missouri. Directly presaging the American Civil War, these forces collided, entering into skirmishes that earned the territory the name of Bleeding Kansas, Kansas was admitted to the United States as a free state on January 29,1861, making it the 34th state to enter the Union. He was roundly condemned by both the conventional Confederate military and the partisan rangers commissioned by the Missouri legislature and his application to that body for a commission was flatly rejected due to his pre-war criminal record
Dinosaurs are a diverse group of reptiles of the clade Dinosauria that first appeared during the Triassic. Although the exact origin and timing of the evolution of dinosaurs is the subject of active research and they became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201 million years ago. Their dominance continued through the Jurassic and Cretaceous periods and ended when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups 66 million years ago, until the late 20th century, all groups of dinosaurs were believed to be extinct. As such, birds were the dinosaur lineage to survive the mass extinction event. This article deals primarily with non-avian dinosaurs, Dinosaurs are a varied group of animals from taxonomic and ecological standpoints. Birds, at over 10,000 living species, are the most diverse group of vertebrates besides perciform fish, using fossil evidence, paleontologists have identified over 500 distinct genera and more than 1,000 different species of non-avian dinosaurs.
Dinosaurs are represented on every continent by both extant species and fossil remains, while dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, evidence suggests that egg laying and nest building are additional traits shared by all dinosaurs.7 meters and heights of 18 meters and were the largest land animals of all time. Still, the idea that dinosaurs were uniformly gigantic is a misconception based in part on preservation bias, as large. Many dinosaurs were small, for example, was only about 50 cm long. Through the first half of the 20th century, before birds were recognized to be dinosaurs, most of the community believed dinosaurs to have been sluggish. Most research conducted since the 1970s, has indicated that all dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction.
The large sizes of some groups, as well as their seemingly monstrous and fantastic nature, have ensured dinosaurs regular appearance in best-selling books and films. Persistent public enthusiasm for the animals has resulted in significant funding for dinosaur science, the term is derived from the Greek words δεινός and σαῦρος. Though the taxonomic name has often interpreted as a reference to dinosaurs teeth, claws. Instead, like many forms of reptile sub-groups, did not exhibit characteristics which were traditionally regarded as reptilian. Under phylogenetic nomenclature, dinosaurs are usually defined as the group consisting of Triceratops, their most recent common ancestor, Birds are now recognized as being the sole surviving lineage of theropod dinosaurs. In traditional taxonomy, birds were considered a class that had evolved from dinosaurs
Phytoliths are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of the plant. These plants take up silica from the soil, whereupon it is deposited within different intracellular and extracellular structures of the plant, Phytoliths come in varying shapes and sizes. Although some use phytolith to refer to all mineral secretions by plants, in contrast, mineralized calcium secretions in cacti are composed of calcium oxalates. There is still debate in the community as to why plants form phytoliths. Studies that have plants in silica-free environments have typically found that plants lacking silica in the environment do not grow well. For example, the stems of plants will collapse when grown in soil lacking silica. In many cases, phytoliths appear to lend structure and support to the plant, much like the spicules in sponges, Phytoliths may provide plants with protection. These rigid silica structures help to make more difficult to consume and digest.
Phytoliths appear to provide physiologic benefits, experimental studies have shown that the silicon dioxide in phytoliths may help to alleviate the damaging effects of toxic heavy metals, such as aluminum. Finally, calcium oxalates serve as a reserve of carbon dioxide, cacti use these as a reserve for photosynthesis during the day when they close their pores to avoid water loss, baobabs use this property to make their trunks more flame-resistant. According to Dolores Piperno, an expert in the field of phytolith analysis and exploratory stage, The first report on phytoliths was published by a German botanist named Struve in 1835. During this time another German scientist named Christian Gottfried Ehrenberg was one of the leaders in the field of phytolith analysis and he developed the first classification system for phytoliths, and analyzed soil samples that were sent to him from all around the world. Botanical phase of research, Phytolith structures in plants gained wide recognition and attention throughout Europe, Research on production and morphology exploded.
Detailed notes and drawings on plant families that produce silica structures, period of ecological research, First applications of phytolith analysis to paleoecological work, mostly in Australia, the United States, the United Kingdom, and Russia. Classification systems for differentiation within plant families became popular, for the first time, phytolith data from pottery are used to track history of clay procurement and pottery manufacture. Around the same time, phytolith data are used as a means of vegetation reconstruction among paleoecologists. A much larger collection on phytolith morphology within varying plant families is assembled. First, soluble silica, called acid, is taken up from the soil when plant roots absorb groundwater
It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometres, it is the fifth-largest continent, for comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km in thickness, Antarctica, on average, is the coldest and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with precipitation of only 200 mm along the coast. The temperature in Antarctica has reached −89.2 °C, though the average for the quarter is −63 °C. Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Organisms native to Antarctica include many types of algae, fungi, protista, where it occurs, is tundra. The continent, remained neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources.
In 1895, the first confirmed landing was conducted by a team of Norwegians, Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then, the treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations, the name Antarctica is the romanised version of the Greek compound word ἀνταρκτική, feminine of ἀνταρκτικός, meaning opposite to the Arctic, opposite to the north. Aristotle wrote in his book Meteorology about an Antarctic region in c.350 B. C, marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A. D. Before acquiring its present geographical connotations, the term was used for locations that could be defined as opposite to the north.
For example, the short-lived French colony established in Brazil in the 16th century was called France Antarctique, the first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. Antarctica has no population and there is no evidence that it was seen by humans until the 19th century. Explorer Matthew Flinders, in particular, has credited with popularising the transfer of the name Terra Australis to Australia. Cook came within about 120 km of the Antarctic coast before retreating in the face of ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals, according to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820, von Bellingshausen, Edward Bransfield, and Nathaniel Palmer
Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and precipitated—that is, become heavy enough to fall under gravity. Rain is a component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystems, as well as water for power plants. The major cause of production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convective clouds such as cumulonimbus which can organize into narrow rainbands. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass, the movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes. The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities, global warming is causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics.
The globally averaged annual precipitation over land is 715 mm, climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Rainfall is measured using rain gauges, rainfall amounts can be estimated by weather radar. Rain is known or suspected on other planets, where it may be composed of methane, sulfuric acid, or even iron rather than water. Air contains water vapor, and the amount of water in a mass of dry air. The amount of moisture in air is commonly reported as relative humidity. How much water vapor a parcel of air can contain before it becomes saturated, warmer air can contain more water vapor than cooler air before becoming saturated. Therefore, one way to saturate a parcel of air is to cool it, the dew point is the temperature to which a parcel must be cooled in order to become saturated. There are four mechanisms for cooling the air to its dew point, adiabatic cooling, conductive cooling, radiational cooling.
Adiabatic cooling occurs when air rises and 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 surface, usually by being blown from one surface to another. 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