Black Sea

The Black Sea is a sea between Southeastern Europe and Western Asia. It is bounded by Europe, Anatolia and the Caucasus, and drains through the Mediterranean into the Atlantic Ocean, via the Aegean Sea and various straits. The Bosphorus Strait connects it to the Sea of Marmara, and the Strait of the Dardanelles connects that sea to the Aegean Sea region of the Mediterranean. These waters separate eastern Europe and western Asia. The Black Sea is also connected to the Sea of Azov by the Strait of Kerch. The Black Sea has an area of 436,400 km2 (168,500 sq mi) (not including the Sea of Azov a maximum depth of 2,212 m (7,257 ft),[2] and a volume of 547,000 km3 (131,000 cu mi The Black Sea forms in an east-west trending elliptical depression which lies between Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine It is constrained by the Pontic Mountains to the south and by the Caucasus Mountains to the east, and features a wide shelf to the northwest. The longest east-west extent is about 1,175 km (730 mi). Important cities along the coast include Batumi, Burgas, Constanța, Giresun, Hopa, Istanbul, Kerch, Mangalia, Năvodari, Novorossiysk, Odessa, Ordu, Poti, Rize, Sinop, Samsun, Sevastopol, Sochi, Sozopol, Sukhumi, Trabzon, Varna, Yalta and Zonguldak. The Black Sea has a positive water balance; that is, a net outflow of water 300 km3 (72 cu mi) per year through the Bosphorus and the Dardanelles into the Aegean Sea. Mediterranean water flows into the Black Sea as part of a two-way hydrological exchange. The Black Sea outflow is cooler and less saline, and floats over the warm, more saline Mediterranean inflow – as a result of differences in density caused by differences in salinity – leading to a significant anoxic layer well below the surface waters. The Black Sea also receives river water from large Eurasian fluvial systems to the north of the Sea, of which the Don, Dnieper and Danube are the most significant.In the past, the water level has varied significantly. Due to these variations in the water level in the basin, the surrounding shelf and associated aprons have sometimes been land. At certain critical water levels it is possible for connections with surrounding water bodies to become established. It is through the most active of these connective routes, the Turkish Straits, that the Black Sea joins the world ocean. When this hydrological link is not present, the Black Sea is an endorheic basin, operating independently of the global ocean system, like the Caspian Sea for example. Currently the Black Sea water level is relatively high, thus water is being exchanged with the Mediterranean. The Turkish Straits connect the Black Sea with the Aegean Sea, and comprise the Bosphorus, the Sea of Marmara and the Dardanelles.

Tree growth

The tree growth habit is an evolutionary adaptation found in different groups of plants: by growing taller, trees are able to compete better for sunlight Trees tend to be long-lived, some reaching several thousand years old, as well as tall.Trees have modified structures such as thicker stems composed of specialized cells that add structural strength and durability, and that allow them to grow taller than non-woody plants and to spread out their foliage. They differ from shrubs, which are also woody plants, by usually growing larger and having a single main stem but the distinction between a small tree and a large shrub is not always clear, made more confusing by the fact that trees may be reduced in size under harsher environmental conditions such as on mountains and subarctic areas. The tree form has evolved separately in unrelated classes of plants in response to similar environmental challenges, making it a classic example of parallel evolution. With an estimated 100,000 species, the number of trees worldwide might total twenty-five percent of all living plant species.The greatest number of these grow in tropical regions and many of these areas have not yet been fully surveyed by botanists, making tree diversity and ranges poorly known.

Penguin

The word penguin first appears in the 16th century as a synonym for great auk When European explorers discovered what are today known as penguins in the Southern Hemisphere, they noticed their similar appearance to the great auk of the Northern Hemisphere, and named them after this bird, although they are not closely related. The etymology of the word penguin is still debated. The English word is not apparently of French, Breton or Spanish origin (the latter two are attributed to the French word pingouin "auk"), but first appears in English or Dutch.Some dictionaries suggest a derivation from Welsh pen, "head" and gwyn, "white", including the Oxford English Dictionary, the American Heritage Dictionary the Century Dictionary and Merriam-Webster on the basis that the name was originally applied to the great auk, either because it was found on White Head Island (Welsh Pen Gwyn) in Newfoundland, or because it had white circles around its eyes (though the head was black). However, the Welsh word pen is also used to mean "front", "foremost part" or "extremity" and therefore "white front" is far more likely to be the sense in which Welsh sailors used the term when referring to the bird. Indeed, the Welsh expression for "bow" or "prow" of a ship is "pen blaen" (front point/tip An alternative etymology links the word to Latin pinguis, which means "fat". In Dutch, the alternative word for penguin is "fat-goose" (vetgans see: Dutch wiki or dictionaries under Pinguïn), and would indicate this bird received its name from its appearance.

Penguins

Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless birds living almost exclusively in the Southern Hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have evolved into flippers. Most penguins feed on krill, fish, squid and other forms of sealife caught while swimming underwater. They spend about half of their lives on land and half in the oceans. Although all penguin species are native to the Southern Hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south. Several species are found in the temperate zone, and one species, the Galápagos penguin, lives near the equator.The largest living species is the emperor penguin (Aptenodytes forsteri): on average adults are about 1.1 m (3 ft 7 in) tall and weigh 35 kg (77 lb) or more. The smallest penguin species is the little blue penguin (Eudyptula minor), also known as the fairy penguin, which stands around 40 cm (16 in) tall and weighs 1 kg (2.2 lb). Among extant penguins, larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates (see also Bergmann's rule). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human. These were not restricted to Antarctic regions; on the contrary, subantarctic regions harboured high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the equator 35 mya, in a climate decidedly warmer than today.

Ship

A ship is a large buoyant watercraft. Ships are generally distinguished from boats based on size, shape and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing, entertainment, public safety, and warfare. Historically, a "ship" was a sailing vessel with at least three square-rigged masts and a full bowsprit. In armed conflict and in daily life ships have become an integral part of modern commercial and military systems. Fishing boats are used by millions of fishermen throughout the world. Military forces operate vessels for naval warfare and to transport and support forces ashore. Commercial vessels, nearly 35,000 in number, carried 7.4 billion tons of cargo in 2007 As of 2011 there are about 104,304 ships with IMO numbers in the world Ships were always a key in history's great explorations and scientific and technological development. Navigators such as Zheng He spread such inventions as the compass and gunpowder. Ships have been used for such purposes as colonization and the slave trade, and have served scientific, cultural, and humanitarian needs. After the 16th century, new crops that had come from and to the Americas via the European seafarers significantly contributed to the world population growth Ship transport has shaped the world's economy into today's energy-intensive pattern.

Cave

Corrasional or erosional caves are those that form entirely by erosion by flowing streams carrying rocks and other sediments. These can form in any type of rock, including hard rocks such as granite. Generally there must be some zone of weakness to guide the water, such as a fault or joint A subtype of the erosional cave is the wind or aeolian cave, carved by wind-born sediments. Many caves formed initially by solutional processes often undergo a subsequent phase of erosional or vadose enlargement where active streams or rivers pass through them.

Tree 2

A tree typically has many secondary branches supported clear of the ground by the trunk. This trunk typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark which serves as a protective barrier. Below the ground, the roots branch and spread out widely; they serve to anchor the tree and extract moisture and nutrients from the soil Above ground the branches divide into smaller branches and shoots. The shoots typically bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development Flowers and fruit may also be present, but some trees such as conifers instead have pollen cones and seed cones; others, such as tree ferns, produce spores instead.Trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of animals and plants. Tropical rainforests are one of the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture. Because of their longevity and usefulness, trees have always been revered and they play a role in many of the world's mythologies.