A sea is a large body of salt water that is surrounded in whole or in part by land.[1][2][a] More broadly, "the sea" is the interconnected system of Earth's salty, oceanic waters—considered as one global ocean or as several principal oceanic divisions. The sea moderates Earth's climate and has important roles in the water cycle, carbon cycle, and nitrogen cycle. Although the sea has been traveled and explored since prehistory, the modern scientific study of the sea—oceanography—dates broadly to the British Challenger expedition of the 1. The sea is conventionally divided into up to five large oceanic sections—including the International Hydrographic Organization's four named oceans[4] (the Atlantic, Pacific, Indian, and Arctic) and the Southern Ocean; [5] smaller, second- order sections, such as the Mediterranean, are known as seas. The sea is an essential aspect of human trade, travel, mineral extraction, and power generation. This has also made it essential to warfare and left major cities exposed to earthquakes and volcanoes from nearby faults; powerful tsunami waves; and hurricanes, typhoons, and cyclones produced in the tropics.
This importance and duality has affected human culture, from early sea gods to the epic poetry of Homer to the changes induced by the Columbian Exchange, from burial at sea to Basho's haikus to hyperrealist marine art, and inspiring music ranging from the shanties in The Complaynt of Scotland to Rimsky- Korsakov's "The Sea and Sinbad's Ship" to A- mei's "Listen to the Sea". It is the scene of leisure activities including swimming, diving, surfing, and sailing. However, population growth, industrialization, and intensive farming have all contributed to present- day marine pollution. Atmospheric carbon dioxide is being absorbed in increasing amounts, lowering its p. H in a process known as ocean acidification. The shared nature of the sea has made overfishing an increasing problem. La Siesta Single-Hängematten-Set Sonrisa mandarine inkl. Neptuno Stahlständer 120kg Tragkraft wetterfest. Lackfolie Breite & Länge wählbar - Weiss ca. 0. The Queen of the Classics or la Pascale: the Easter race. The race is organised by the media group Amaury Sport Organisation annually in mid-April. Tides are the regular rise and fall in water level experienced by seas and oceans in response to the gravitational influences of the Moon and the Sun, and the effects of the Earth's rotation. At any given place, the water rises over the course of the tidal cycle to a maximum height known as "high tide" before ebbing away again to a minimum "low tide" level. As the water recedes, it uncovers more and more of the foreshore or intertidal zone. The difference in height between the high tide and low tide is known as the tidal range or tidal amplitude.[5. Tidal bores can occur at the mouths of rivers, where the force of the incoming tide pushes waves of seawater upstream against the current. At Hangzhou in China, the bore can reach 9 meters (3. There is a broader spectrum of higher animal taxa in the sea than on land, many marine species have yet to be discovered, and the number known to science is expanding annually.[1. Some vertebrates such as seabirds, seals, and sea turtles return to the land to breed but fish, cetaceans, and sea snakes have a completely aquatic lifestyle and many invertebrate phyla are entirely marine. In fact, the oceans teem with life and provide many varying microhabitats.[1. One of these is the surface film which—despite being tossed about by the movement of waves—provides a rich environment and is home to bacteria, fungi, microalgae, protozoa, fish eggs, and various larvae. Since the development of coordinated fleets of ships capable of landing an invasion force, naval warfare has been an important aspect in the defense (or conquest) of maritime states. The first naval battle in recorded history saw Suppiluliuma II of the Hittites burn a Cypriot fleet at sea in 1. BC.[2. 11] Shortly after, the fleets of the Sea Peoples disrupted the entire Eastern Mediterranean: over a period of about 5. Pylos and Gaza.[2. As empires grew and their armies became too large to live off the lands through which they passed, disruption of their supply fleets also became a powerful tactic. The 4. 80 BC Battle of Salamis largely determined the course of the Persian Wars[2. Themistocles's deception and superior strategy left the Athenians capable of disrupting sea- borne supplies at will and potentially striking at the pontoon bridges across the Hellespont, cutting off the Persians' line of retreat.[2. During the age of wooden ships, however, great fleets were burdensome to maintain and always liable to destruction by contrary weather, most famously in the case of the two kamikaze typhoons that destroyed the Mongol invasions of Japan in AD 1. A sea is a large body of salt water that is surrounded in whole or in part by land.[1][2][a] More broadly, "the sea" is the interconnected system of Earth's salty. Years of training and/or experience are needed to become a skilled plumber; some jurisdictions also require that plumbers be licensed. Some needed skills. Do it yourself (DIY) is the method of building, modifying, or repairing things without the direct aid of experts or professionals. Academic research describes DIY as. Silicon is a chemical element with symbol Si and atomic number 1. A hard and brittle crystalline solid with a blue- gray metallic luster, it is a tetravalent metalloid. It is a member of group 1. It is rather unreactive, though less so than germanium, and has great chemical affinity for oxygen; as such, it was first prepared and characterized in pure form only in 1. J? ns Jakob Berzelius. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. Over 9. 0% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 2. The outer electron orbital of silicon, like that of carbon, has four valence electrons. The 1s, 2s, 2p and 3s subshells are completely filled while the 3p subshell contains two electrons out of a possible six. Silicon is a semiconductor. It has a negative temperature coefficient of resistance, since the number of free charge carriers increases with temperature. The electrical resistance of single crystal silicon significantly changes under the application of mechanical stress due to the piezoresistive effect.[1. Heavily boron- doped silicon is a type II superconductor with a transition temperature Tc of 0. K. Silicon in its more common crystalline form was not prepared until 3. Deville.[2. 6][2. By electrolyzing a mixture of sodium chloride and aluminium chloride containing approximately 1. Later, more cost- effective methods have been developed to isolate several allotrope forms, the most recent being silicene. Because silicon is an important element in high- technology semiconductor devices, many places in the world bear its name. For example, Santa Clara Valley in California acquired the nickname Silicon Valley since the element is the base material used in the semiconductor industry located there. Other locations have been nicknamed for similar reasons, including Silicon Forest in Oregon, Silicon Hills in Austin, Texas, Silicon Slopes in Salt Lake City, Utah, Silicon Saxony in Germany, Silicon Valley in India, Silicon Border in Mexicali, Mexico, Silicon Fen in Cambridge, England, Silicon Roundabout in London, Silicon Glen in Scotland, and Silicon Gorge in Bristol, England.
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