Borneo is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, east of Sumatra; the island is politically divided among three countries: Malaysia and Brunei in the north, Indonesia to the south. 73% of the island is Indonesian territory. In the north, the East Malaysian states of Sabah and Sarawak make up about 26% of the island. Additionally, the Malaysian federal territory of Labuan is situated on a small island just off the coast of Borneo; the sovereign state of Brunei, located on the north coast, comprises about 1% of Borneo's land area. A little more than half of the island is in the Northern Hemisphere including Brunei and the Malaysian portion, while the Indonesian portion spans both the Northern and Southern hemispheres. Borneo is home to one of the oldest rainforests in the world; the island is known by many names. Internationally it is known as Borneo, after Brunei, derived from European contact with the kingdom in the 16th century during the Age of Exploration.
The name Brunei derives from the Sanskrit word váruṇa, meaning either "water" or Varuna, the Vedic god of rain. Indonesian natives called it Kalimantan, derived from the Sanskrit word Kalamanthana, meaning "burning weather island". In earlier times, the island was known by other names. In 977, Chinese records began to use the term Bo-ni to refer to Borneo. In 1225, it was mentioned by the Chinese official Chau Ju-Kua; the Javanese manuscript Nagarakretagama, written by Majapahit court poet Mpu Prapanca in 1365, mentioned the island as Nusa Tanjungnagara, which means the island of the Tanjungpura Kingdom. Borneo is surrounded by the South China Sea to the north and northwest, the Sulu Sea to the northeast, the Celebes Sea and the Makassar Strait to the east, the Java Sea and Karimata Strait to the south. To the west of Borneo are the Malay Peninsula and Sumatra. To the south and east are islands of Indonesia: Java and Sulawesi, respectively. To the northeast are the Philippine Islands. With an area of 743,330 square kilometres, it is the third-largest island in the world, is the largest island of Asia.
Its highest point is Mount Kinabalu in Sabah, with an elevation of 4,095 m. Before sea levels rose at the end of the last Ice Age, Borneo was part of the mainland of Asia, with Java and Sumatra, the upland regions of a peninsula that extended east from present day Indochina; the South China Sea and Gulf of Thailand now submerge the former low-lying areas of the peninsula. Deeper waters separating Borneo from neighbouring Sulawesi prevented a land connection to that island, creating the divide known as Wallace's Line between Asian and Australia-New Guinea biological regions; the largest river system is the Kapuas in West Kalimantan, with a length of 1,000 km. Other major rivers include the Mahakam in East Kalimantan, the Barito in South Kalimantan, Rajang in Sarawak and Kinabatangan in Sabah. Borneo has significant cave systems. In Sarawak, the Clearwater Cave has one of the world's longest underground rivers while Deer Cave is home to over three million bats, with guano accumulated to over 100 metres deep.
The Gomantong Caves in Sabah has been dubbed as the "Cockroach Cave" due to the presence of millions of cockroaches inside the cave. The Gunung Mulu National Park in Sarawak and Sangkulirang-Mangkalihat Karst in East Kalimantan which a karst areas contains thousands of smaller caves; the Borneo rainforest is estimated to be around 140 million years old, making it one of the oldest rainforests in the world. It is the centre of the evolution and distribution of many endemic species of plants and animals, the rainforest is one of the few remaining natural habitats for the endangered Bornean orangutan, it is an important refuge for many endemic forest species, including the Borneo elephant, the eastern Sumatran rhinoceros, the Bornean clouded leopard, the hose's palm civet and the dayak fruit bat. Peat swamp forests occupy the entire coastline of Borneo; the soil of the peat swamp are comparatively infertile, while it is known to be the home of various bird species such as the hook-billed bulbul, helmeted hornbill and rhinoceros hornbill.
There are about 15,000 species of flowering plants with 3,000 species of trees, 221 species of terrestrial mammals and 420 species of resident birds in Borneo. There are about 440 freshwater fish species in Borneo; the Borneo river shark is known only from the Kinabatangan River. In 2010, the World Wide Fund for Nature stated that 123 species have been discovered in Borneo since the "Heart of Borneo" agreement was signed in 2007; the WWF has classified the island into seven distinct ecoregions. Most are lowland regions: Borneo lowland rain forests cover most of the island, with an area of 427,500 square kilometres; the Borneo montane rain forests lie in the central highlands of the island, above the 1,000 metres elevation. The Tropical and subtropical grasslands and shrublands on South Kalimantan; the highest elevations of Mount Kinabalu are home to the Kinabalu mountain alpine meadow, an alpine shrubland notable for its numerous endemic species, including many orchids. The island had extensive rainforest cover, but the area w
The tree line is the edge of the habitat at which trees are capable of growing. It is found at high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions; the tree line is sometimes distinguished from a lower timberline or forest line, the line below which trees form a forest with a closed canopy. At the tree line, tree growth is sparse and deformed by wind and cold; this is sometimes known as krummholz. The tree line appears well-defined, but it can be a more gradual transition. Trees grow shorter and at lower densities as they approach the tree line, above which they cease to exist. Several types of tree lines are defined in ecology and geography: An alpine tree line is the highest elevation that sustains trees; the climate above the tree line of mountains is called an alpine climate, the terrain can be described as alpine tundra. Treelines on north-facing slopes in the northern hemisphere are lower than on south-facing slopes, because the increased shade on north-facing slopes means the snowpack takes longer to melt.
This shortens the growing season for trees. In the southern hemisphere, the south-facing slopes have the shorter growing season; the alpine tree line boundary is abrupt: it forms a transition zone between closed forest below and treeless alpine tundra above. This zone of transition occurs "near the top of the tallest peaks in the northeastern United States, high up on the giant volcanoes in central Mexico, on mountains in each of the 11 western states and throughout much of Canada and Alaska". Environmentally dwarfed shrubs form the upper limit; the decrease in air temperature due to increasing elevation causes the alpine climate. The rate of decrease can vary in different mountain chains, from 3.5 °F per 1,000 feet of elevation gain in the dry mountains of the western United States, to 1.4 °F per 1,000 feet in the moister mountains of the eastern United States. Skin effects and topography can create microclimates. Compared with arctic timberlines, alpine timberlines may receive fewer than half of the number of degree days based on air temperature, but because solar radiation intensities are greater at alpine than at arctic timberlines the number of degree days calculated from leaf temperatures may be similar.
Summer warmth sets the limit to which tree growth can occur, for while timberline conifers are frost-hardy during most of the year, they become sensitive to just 1 or 2 degrees of frost in mid-summer. A series of warm summers in the 1940s seems to have permitted the establishment of "significant numbers" of spruce seedlings above the previous treeline in the hills near Fairbanks, Alaska. Survival depends on a sufficiency of new growth to support the tree; the windiness of high-elevation sites is a potent determinant of the distribution of tree growth. Wind can mechanically damage tree tissues directly, including blasting with windborne particles, may contribute to the desiccation of foliage of shoots that project above snow cover. At the alpine timberline, tree growth is inhibited when excessive snow lingers and shortens the growing season to the point where new growth would not have time to harden before the onset of fall frost. Moderate snowpack, may promote tree growth by insulating the trees from extreme cold during the winter, curtailing water loss, prolonging a supply of moisture through the early part of the growing season.
However, snow accumulation in sheltered gullies in the Selkirk Mountains of southeastern British Columbia causes the timberline to be 400 metres lower than on exposed intervening shoulders. In a desert, the tree line marks; these tend to be called the "lower" tree line, occur below about 5,000 ft elevation in the desert of the southwestern United States. The desert tree line tends to be lower on pole-facing slopes than equator-facing slopes, because the increased shade on the former keeps them cooler and prevents moisture from evaporating as giving trees a longer growing season and more access to water. In some mountainous areas, higher elevations above the condensation line, or on equator-facing and leeward slopes, can result in low rainfall and increased exposure to solar radiation; this dries out the soil. Many south-facing ridges of the mountains of the Western U. S. have a lower treeline than the northern faces because of aridity. Different tree species have different tolerances to cold. Mountain ranges isolated by oceans or deserts may have restricted repertoires of tree species with gaps that are above the alpine tree line for some species yet below the desert tree line for others.
For example, several mountain ranges in the Great Basin of North America have lower belts of Pinyon Pines and Junipers separated by intermediate brushy but treeless zones from upper belts of Limber and Bristlecone Pines. On coasts and isolated mountains the tree line is much lower than in corresponding altitudes inland and in larger, more complex mountain systems, because strong winds reduce tree growth. In addition the lack of suitable soil, such as along talus slopes or exposed rock formations, prevents trees from gaining an adequate foothold and exposes them to drought and sun; the arctic tree line is the northernmost latitude in the Northern Hemisphere where tr
Snow refers to forms of ice crystals that precipitate from the atmosphere and undergo changes on the Earth's surface. It pertains to frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size and accumulate on surfaces metamorphose in place, melt, slide or sublimate away. Snowstorms develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles and rime; as snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form. Otherwise, snow melts seasonally, causing runoff into streams and rivers and recharging groundwater. Major snow-prone areas include the polar regions, the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture and cold temperatures.
In the Southern Hemisphere, snow is confined to mountainous areas, apart from Antarctica. Snow affects such human activities as transportation: creating the need for keeping roadways and windows clear. Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold. Snow develops in clouds; the physics of snow crystal development in clouds results from a complex set of variables that include moisture content and temperatures. The resulting shapes of the falling and fallen crystals can be classified into a number of basic shapes and combinations, thereof; some plate-like and stellar-shaped snowflakes can form under clear sky with a cold temperature inversion present. Snow clouds occur in the context of larger weather systems, the most important of, the low pressure area, which incorporate warm and cold fronts as part of their circulation. Two additional and locally productive sources of snow are lake-effect storms and elevation effects in mountains.
Mid-latitude cyclones are low pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards. During a hemisphere's fall and spring, the atmosphere over continents can be cold enough through the depth of the troposphere to cause snowfall. In the Northern Hemisphere, the northern side of the low pressure area produces the most snow. For the southern mid-latitudes, the side of a cyclone that produces the most snow is the southern side. A cold front, the leading edge of a cooler mass of air, can produce frontal snowsqualls—an intense frontal convective line, when temperature is near freezing at the surface; the strong convection that develops has enough moisture to produce whiteout conditions at places which line passes over as the wind causes intense blowing snow. This type of snowsquall lasts less than 30 minutes at any point along its path but the motion of the line can cover large distances. Frontal squalls may form a short distance ahead of the surface cold front or behind the cold front where there may be a deepening low pressure system or a series of trough lines which act similar to a traditional cold frontal passage.
In situations where squalls develop post-frontally it is not unusual to have two or three linear squall bands pass in rapid succession only separated by 25 miles with each passing the same point in 30 minutes apart. In cases where there is a large amount of vertical growth and mixing the squall may develop embedded cumulonimbus clouds resulting in lightning and thunder, dubbed thundersnow. A warm front can produce snow for a period, as warm, moist air overrides below-freezing air and creates precipitation at the boundary. Snow transitions to rain in the warm sector behind the front. Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water, warming the lower layer of air which picks up water vapor from the lake, rises up through the colder air above, freezes and is deposited on the leeward shores; the same effect occurs over bodies of salt water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the moving air mass is uplifted by the orographic influence of higher elevations on the downwind shores.
This uplifting can produce narrow but intense bands of precipitation, which deposit at a rate of many inches of snow each hour resulting in a large amount of total snowfall. The areas affected by lake-effect snow are called snowbelts; these include areas east of the Great Lakes, the west coasts of northern Japan, the Kamchatka Peninsula in Russia, areas near the Great Salt Lake, Black Sea, Caspian Sea, Baltic Sea, parts of the northern Atlantic Ocean. Orographic or relief snowfall is caused when masses of air pushed by wind are forced up the side of elevated land formations, such as large mountains; the lifting of air up the side of a mountain or range results in adiabatic cooling, condensation and precipitation. Moisture is removed by orographic lift, leaving drier, warmer air on the leeward side; the resulting enhanced productivity of snow fall and the decrease in temperature with elevation means that snow depth
In physical geography, tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word тӯндар meaning "uplands", "treeless mountain tract". Tundra vegetation is composed of dwarf shrubs and grasses, lichens. Scattered trees grow in some tundra regions; the ecotone between the tundra and the forest is known as timberline. There are three regions and associated types of tundra: Arctic tundra, alpine tundra, Antarctic tundra. Arctic tundra occurs in the far Northern Hemisphere, north of the taiga belt; the word "tundra" refers only to the areas where the subsoil is permafrost, or permanently frozen soil. Permafrost tundra includes vast areas of northern Canada; the polar tundra is home to several peoples who are nomadic reindeer herders, such as the Nganasan and Nenets in the permafrost area. Arctic tundra is frozen for much of the year; the soil there is frozen from 25 to 90 cm down. Instead and sometimes rocky land can only support certain kinds of Arctic vegetation, low growing plants such as moss and lichen.
There are two main seasons and summer, in the polar tundra areas. During the winter it is cold and dark, with the average temperature around −28 °C, sometimes dipping as low as −50 °C. However, extreme cold temperatures on the tundra do not drop as low as those experienced in taiga areas further south. During the summer, temperatures rise somewhat, the top layer of seasonally-frozen soil melts, leaving the ground soggy; the tundra is covered in marshes, lakes and streams during the warm months. Daytime temperatures during the summer rise to about 12 °C but can drop to 3 °C or below freezing. Arctic tundras are sometimes the subject of habitat conservation programs. In Canada and Russia, many of these areas are protected through a national Biodiversity Action Plan. Tundra tends to be windy, with winds blowing upwards of 50–100 km/h. However, in terms of precipitation, it is desert-like, with only about 15–25 cm falling per year. Although precipitation is light, evaporation is relatively minimal. During the summer, the permafrost thaws just enough to let plants grow and reproduce, but because the ground below this is frozen, the water cannot sink any lower, so the water forms the lakes and marshes found during the summer months.
There is a natural pattern of accumulation of fuel and wildfire which varies depending on the nature of vegetation and terrain. Research in Alaska has shown fire-event return intervals that vary from 150 to 200 years, with dryer lowland areas burning more than wetter highland areas; the biodiversity of tundra is low: 1,700 species of vascular plants and only 48 species of land mammals can be found, although millions of birds migrate there each year for the marshes. There are a few fish species. There are few species with large populations. Notable animals in the Arctic tundra include reindeer, musk ox, Arctic hare, Arctic fox, snowy owl and polar bears near the ocean. Tundra is devoid of poikilotherms such as frogs or lizards. Due to the harsh climate of Arctic tundra, regions of this kind have seen little human activity though they are sometimes rich in natural resources such as petroleum, natural gas and uranium. In recent times this has begun to change in Alaska and some other parts of the world: for example, the Yamalo-Nenets Autonomous Okrug produces 90% of Russia's natural gas.
A severe threat to tundra is global warming. The melting of the permafrost in a given area on human time scales could radically change which species can survive there. Another concern is that about one third of the world's soil-bound carbon is in taiga and tundra areas; when the permafrost melts, it releases carbon in the form of carbon dioxide and methane, both of which are greenhouse gases. The effect has been observed in Alaska. In the 1970s the tundra was a carbon sink. Methane is produced when vegetation decays in wetlands; the amount of greenhouse gases which will be released under projected scenarios for global warming have not been reliably quantified by scientific studies, although a few studies were reported to be underway in 2011. It is uncertain whether the impact of increased greenhouse gases from this source will be minimal or massive. In locations where dead vegetation and peat has accumulated, there is a risk of wildfire, such as the 1,039 km2 of tundra which burned in 2007 on the north slope of the Brooks Range in Alaska.
Such events may both contribute to global warming. Antarctic tundra occurs on Antarctica and on several Antarctic and subantarctic islands, including South Georgia and the South Sandwich Islands and the Kerguelen Islands. Most of Antarctica is too cold and dry to support vegetation, most of the continent is covered by ice fields. However, some portions of the continent the Antarctic Peninsula, have areas of rocky soil that support plant life; the flora presently consists of around 300–400 lichens, 100 mosses, 25 liverworts, aro
The Appalachian Mountains called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed 480 million years ago during the Ordovician Period, they once reached elevations similar to those of the Alps and the Rocky Mountains before experiencing natural erosion. The Appalachian chain is a barrier to east–west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east–west. Definitions vary on the precise boundaries of the Appalachians; the United States Geological Survey defines the Appalachian Highlands physiographic division as consisting of thirteen provinces: the Atlantic Coast Uplands, Eastern Newfoundland Atlantic, Maritime Acadian Highlands, Maritime Plain, Notre Dame and Mégantic Mountains, Western Newfoundland Mountains, Blue Ridge and Ridge, Saint Lawrence Valley, Appalachian Plateaus, New England province, the Adirondack areas. A common variant definition does not include the Adirondack Mountains, which geologically belong to the Grenville Orogeny and have a different geological history from the rest of the Appalachians.
The mountain range is in the United States but it extends into southeastern Canada, forming a zone from 100 to 300 mi wide, running from the island of Newfoundland 1,500 mi southwestward to Central Alabama in the United States. The range covers parts of the islands of Saint Pierre and Miquelon, which comprise an overseas territory of France; the system is divided into a series of ranges, with the individual mountains averaging around 3,000 ft. The highest of the group is Mount Mitchell in North Carolina at 6,684 feet, the highest point in the United States east of the Mississippi River; the term Appalachian refers to several different regions associated with the mountain range. Most broadly, it refers to the entire mountain range with its surrounding hills and the dissected plateau region; the term is used more restrictively to refer to regions in the central and southern Appalachian Mountains including areas in the states of Kentucky, Virginia, West Virginia, North Carolina, as well as sometimes extending as far south as northern Alabama and western South Carolina, as far north as Pennsylvania, southern Ohio, parts of southern upstate New York.
The Ouachita Mountains in Arkansas and Oklahoma were part of the Appalachians as well but became disconnected through geologic history. While exploring inland along the northern coast of Florida in 1528, the members of the Narváez expedition, including Álvar Núñez Cabeza de Vaca, found a Native American village near present-day Tallahassee, Florida whose name they transcribed as Apalchen or Apalachen; the name was soon altered by the Spanish to Apalachee and used as a name for the tribe and region spreading well inland to the north. Pánfilo de Narváez's expedition first entered Apalachee territory on June 15, 1528, applied the name. Now spelled "Appalachian," it is the fourth-oldest surviving European place-name in the US. After the de Soto expedition in 1540, Spanish cartographers began to apply the name of the tribe to the mountains themselves; the first cartographic appearance of Apalchen is on Diego Gutierrez's map of 1562. The name was not used for the whole mountain range until the late 19th century.
A competing and more popular name was the "Allegheny Mountains", "Alleghenies", "Alleghania". In the early 19th century, Washington Irving proposed renaming the United States either Appalachia or Alleghania. In U. S. dialects in the southern regions of the Appalachians, the word is pronounced, with the third syllable sounding like "latch". In northern parts of the mountain range, it is pronounced or. There is great debate between the residents of the regions as to which pronunciation is the more correct one. Elsewhere, a accepted pronunciation for the adjective Appalachian is, with the last two syllables "-ian" pronounced as in the word "Romanian"; the whole system may be divided into three great sections: Northern: The northern section runs from the Canadian province of Newfoundland and Labrador to the Hudson River. It includes the Long Range Mountains and Annieopsquotch Mountains on the island of Newfoundland, Chic-Choc Mountains and Notre Dame Range in Quebec and New Brunswick, scattered elevations and small ranges elsewhere in Nova Scotia and New Brunswick, the Longfellow Mountains in Maine, the White Mountains in New Hampshire, the Green Mountains in Vermont, The Berkshires in Massachusetts and Connecticut.
The Metacomet Ridge Mountains in Connecticut and south-central Massachusetts, although contained within the Appalachian province, is a younger system and not geologically associated with the Appalachians. The Monteregian Hills, which cross the Green Mountains in Quebec, are unassociated with the Appalachians. Central: The central section goes from the Hudson Valley to the New River running through Virginia and West Virginia, it comprises the Valley Ridges between the Allegheny Front of the Allegheny Plateau and the Great Appalachian Valley, the New York–New Jersey Highlands, the Taconic Mountains in New York, a large portion of the Blue Ridge. Southern: The southern section runs from the New River onwards, it consists of the prolongation of the Blue Ridge, divided into the Western Blue Ridge Front and the Eastern Blue Ridge Front, the Ridge-and-Valley Appalachians, the Cumberland Plateau. The Adirondack Mountains in New Y
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
New Guinea is a large island separated by a shallow sea from the rest of the Australian continent. It is the world's third-largest island, after Australia and Greenland, covering a land area of 785,753 km2, arguably the largest wholly or within the Southern Hemisphere and Oceania; the eastern half of the island is the major land mass of the independent state of Papua New Guinea. The western half, referred to as either Western New Guinea or West Papua, has been administered by Indonesia since 1963 and comprises the provinces of Papua and West Papua; the island has been known by various names: The name Papua was used to refer to parts of the island before contact with the West. Its etymology is unclear; the name came from papo and ua, which means "not united" or, "territory that geographically is far away". Ploeg reports that the word papua is said to derive from the Malay word papua or pua-pua, meaning "frizzly-haired", referring to the curly hair of the inhabitants of these areas. Another possibility, put forward by Sollewijn Gelpke in 1993, is that it comes from the Biak phrase sup i papwa which means'the land below' and refers to the islands west of the Bird's Head, as far as Halmahera.
Whatever its origin, the name Papua came to be associated with this area, more with Halmahera, known to the Portuguese by this name during the era of their colonization in this part of the world. When the Portuguese and Spanish explorers arrived in the island via the Spice Islands, they referred to the island as Papua. However, the name New Guinea was used by Westerners starting with the Spanish explorer Yñigo Ortiz de Retez in 1545, referring to the similarities of the indigenous people's appearance with the natives of the Guinea region of Africa; the name is one of several toponyms sharing similar etymologies meaning "land of the blacks" or similar meanings, in reference to the dark skin of the inhabitants. The Dutch, who arrived under Jacob Le Maire and Willem Schouten, called it Schouten island, but this name was used only to refer to islands off the north coast of Papua proper, the Schouten Islands or Biak Island; when the Dutch colonized it as part of Netherlands East Indies, they called it Nieuw Guinea.
The name Irian was used in the Indonesian language to refer to the island and Indonesian province, as "Irian Jaya Province". The name was promoted in 1945 by brother of the future governor Frans Kaisiepo, it is taken from the Biak language of Biak Island, means "to rise", or "rising spirit". Irian is the name used in the Biak language and other languages such as Serui and Waropen; the name was used until 2001, when the name Papua was again used for the province. The name Irian, favored by natives, is now considered to be a name imposed by the authority of Jakarta. New Guinea is an island to the north of the Australian mainland, but south of the equator, it is isolated by the Arafura Sea to the west, the Torres Strait and Coral Sea to the east. Sometimes considered to be the easternmost island of the Indonesian archipelago, it lies north of Australia's Top End, the Gulf of Carpentaria and Cape York peninsula, west of the Bismarck Archipelago and the Solomon Islands Archipelago. Politically, the western half of the island comprises two provinces of Indonesia: Papua and West Papua.
The eastern half forms the mainland of the country of Papua New Guinea. The shape of New Guinea is compared to that of a bird-of-paradise, this results in the usual names for the two extremes of the island: the Bird's Head Peninsula in the northwest, the Bird's Tail Peninsula in the southeast. A spine of east–west mountains, the New Guinea Highlands, dominates the geography of New Guinea, stretching over 1,600 km from the'head' to the'tail' of the island, with many high mountains over 4,000 m; the western-half of the island of New Guinea contains the highest mountains in Oceania, rising up to 4,884 m high, higher than Mont Blanc in Europe, ensuring a steady supply of rain from the equatorial atmosphere. The tree line is around 4,000 m elevation and the tallest peaks contain permanent equatorial glaciers—which have been retreating since at least 1936. Various other smaller mountain ranges occur both west of the central ranges. Except in high elevations, most areas possess a warm humid climate throughout the year, with some seasonal variation associated with the northeast monsoon season.
The highest peaks on the island of New Guinea are: Puncak Jaya, sometimes known by its former Dutch name Carstensz Pyramid, is a mist-covered limestone mountain peak on the Indonesian side of the border. At 4,884 metres, Puncak Jaya makes New Guinea the world's fourth-highest landmass after Afro-Eurasia and Antarctica. Puncak Mandala located in Papua, is the second-highest peak on the island at 4,760 metres. Puncak Trikora in Papua, is 4,750 metres. Mount Wilhelm is the highest peak on the PNG side of the border at 4,509 metres, its granite peak is the highest point of the Bismarck Range. Mount Giluwe 4,368 metres is the second-highest summit in PNG, it is the highest volcanic peak in Oceania. Another major habitat featur