1.
Plymouth Sound
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Plymouth Sound, or locally just The Sound, is a bay on the English Channel at Plymouth in England. Its southwest and southeast corners are Penlee Point in Cornwall and Wembury Point in Devon and its northern limit is Plymouth Hoe giving a north-south distance of nearly 3 nautical miles. The Sound has three water entrances, the marine entrance is from the English Channel to the south, with a deep-water channel to the west of the Plymouth Breakwater. There are two inlets, one, from the northwest, is from the River Tamar via the Hamoaze and Devonport Dockyard. The other, at northeast, is from the River Plym disgorging into its narrow estuary, in addition to ships of the Royal Navy, large commercial vessels, including ferries to France and Spain use the Sound from Millbay Docks. Fishing vessels use it from Sutton Harbour beside the old town of Plymouth, there are marinas at Sutton Harbour, Mount Wise in the Hamoaze and at Turnchapel. Waterborne traffic in the Sound is controlled by the Queens Harbour Master for Plymouth, in the centre of the Sound, midway between Bovisand Bay and Cawsand Bay, is Plymouth Breakwater, which creates a harbour protecting anchored ships from the frequent south-western storms. The breakwater is around 1,700 yards long, stands in around 11 metres /36 feet of water and was built by John Rennie, the breakwater has a 23-metre-tall lighthouse on its western end and a 9-metre-tall beacon with a spherical cage on top at the eastern end. It is said that the cage is a device designed to keep wrecked sailors from drowning in the huge waves of a storm on the low-lying breakwater. Drakes Island is 400 metres long and around 100 metres wide and it was fortified to defend Drakes Channel, the only deep-water route to Devonport. The Bridge is a reef that links Drakes Island and the Cornish mainland. At low water the depth of the Bridge can be less than one metre, in World War I this natural barrier was supplemented by other obstructions to prevent submarines and small ships attacking the naval base. Mount Batten, a former Royal Air Force flying boat and search, T. E. Lawrence was stationed here as Aircraftman Shaw. Over the years, the Sound has been defended by Drakes Island, Picklecombe Fort, Cawsand Fort, a harbour and reservoir were built at Bovisand before the fort existed to supply men-o-war anchored in the Sound with fresh water. Joseph Whidbey supervised the building of the Breakwater from Bovisand Lodge, the Titanic was supposed to have docked here briefly on its return voyage to Britain, and the ship had a painting of Plymouth sound on board. This event caused a local and national sensation as thousands took to the water, several paintings in Londons National Maritime Museum document the event, such as the one shown here. The Sound has been the site of a number of crashes and shipwrecks, Die Fraumetta Catharina von Flensburg. The P&O ship Nepaul sank on the Shagstone in December 1890, a Short Sunderland flying boat crashed in March 1942 between the Breakwater Fort and the breakwater lighthouse killing five passengers
2.
United Kingdom
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The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom or Britain, is a sovereign country in western Europe. Lying off the north-western coast of the European mainland, the United Kingdom includes the island of Great Britain, Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state—the Republic of Ireland. The Irish Sea lies between Great Britain and Ireland, with an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world and the 11th-largest in Europe. It is also the 21st-most populous country, with an estimated 65.1 million inhabitants, together, this makes it the fourth-most densely populated country in the European Union. The United Kingdom is a monarchy with a parliamentary system of governance. The monarch is Queen Elizabeth II, who has reigned since 6 February 1952, other major urban areas in the United Kingdom include the regions of Birmingham, Leeds, Glasgow, Liverpool and Manchester. The United Kingdom consists of four countries—England, Scotland, Wales, the last three have devolved administrations, each with varying powers, based in their capitals, Edinburgh, Cardiff and Belfast, respectively. The relationships among the countries of the UK have changed over time, Wales was annexed by the Kingdom of England under the Laws in Wales Acts 1535 and 1542. A treaty between England and Scotland resulted in 1707 in a unified Kingdom of Great Britain, which merged in 1801 with the Kingdom of Ireland to form the United Kingdom of Great Britain and Ireland. Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain, there are fourteen British Overseas Territories. These are the remnants of the British Empire which, at its height in the 1920s, British influence can be observed in the language, culture and legal systems of many of its former colonies. The United Kingdom is a country and has the worlds fifth-largest economy by nominal GDP. The UK is considered to have an economy and is categorised as very high in the Human Development Index. It was the worlds first industrialised country and the worlds foremost power during the 19th, the UK remains a great power with considerable economic, cultural, military, scientific and political influence internationally. It is a nuclear weapons state and its military expenditure ranks fourth or fifth in the world. The UK has been a permanent member of the United Nations Security Council since its first session in 1946 and it has been a leading member state of the EU and its predecessor, the European Economic Community, since 1973. However, on 23 June 2016, a referendum on the UKs membership of the EU resulted in a decision to leave. The Acts of Union 1800 united the Kingdom of Great Britain, Scotland, Wales and Northern Ireland have devolved self-government
3.
Atmospheric optics
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Atmospheric optics deals with how the unique optical properties of the Earths atmosphere cause a wide range of spectacular optical phenomena. The blue color of the sky is a result of Rayleigh scattering which redirects higher frequency sunlight back into the field of view of the observer. Because blue light is scattered more easily than red light, the sun takes on a reddish hue when it is observed through a thick atmosphere, additional particulate matter in the sky can scatter different colors at different angles creating colorful glowing skies at dusk and dawn. Scattering off of ice crystals and other particles in the atmosphere are responsible for halos, afterglows, coronas, rays of sunlight, the variation in these kinds of phenomena is due to different particle sizes and geometries. Mirages are optical phenomena in which light rays are bent due to variations in the refraction index of air. Other optical phenomena associated with include the Novaya Zemlya effect where the sun appears to rise earlier or set later than predicted with a distorted shape. Rainbows are the result of a combination of reflection and dispersive refraction of light in raindrops. Because rainbows are seen on the side of the sky as the sun. He said that judging the distance of an object depends on there being a sequence of intervening bodies between the object and the observer. With the Moon, however, there are no intervening objects, therefore, since the size of an object depends on its observed distance, which is in this case inaccurate, the Moon appears larger on the horizon. For over 100 years, research on the Moon illusion has been conducted by scientists who invariably have been psychologists specializing in human perception. After reviewing the different explanations in their 2002 book The Mystery of the Moon Illusion, Ross. Light from the sky is a result of the scattering of sunlight, on a sunny day Rayleigh scattering gives the sky a blue gradient — dark in the zenith, light near the horizon. Light that comes in from overhead encounters 1/38th of the air mass that light coming along a horizon path encounters, so, fewer particles scatter the zenith sunbeam, and therefore the light remains a darker blue. The blueness is at the horizon because the light coming from great distances is also preferentially scattered. This results in a red shift of the far lightsources that is compensated by the hue of the scattered light in the line of sight. In other words, the red light scatters also, if it does so at a point a distance from the observer it has a much higher chance of reaching the observer than blue light. At distances nearing infinity the light is therefore white
4.
Ray (optics)
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In optics a ray is an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow. This allows even very complex systems to be analyzed mathematically or simulated by computer. Ray theory does not describe phenomena such as interference and diffraction, a light ray is a line that is perpendicular to the lights wavefronts, its tangent is collinear with the wave vector. Light rays in homogeneous media are straight and they bend at the interface between two dissimilar media and may be curved in a medium in which the refractive index changes. Geometric optics describes how rays propagate through an optical system, objects to be imaged are treated as collections of independent point sources, each producing spherical wavefronts and corresponding outward rays. Rays from each point can be mathematically propagated to locate the corresponding point on the image. There are many special rays that are used in modelling to analyze an optical system. These are defined and described below, grouped by the type of system they are used to model, an incident ray is a ray of light that strikes a surface. The angle between this ray and the perpendicular or normal to the surface is the angle of incidence, the reflected ray corresponding to a given incident ray, is the ray that represents the light reflected by the surface. The angle between the normal and the reflected ray is known as the angle of reflection. The Law of Reflection says that for a surface, the angle of reflection always equals the angle of incidence. The refracted ray or transmitted ray corresponding to an incident ray represents the light that is transmitted through the surface. The angle between this ray and the normal is known as the angle of refraction, and it is given by Snells Law. Conservation of energy requires that the power in the incident ray must equal the sum of the power in the ray, the power in the reflected ray. If the material is birefringent, the ray may split into ordinary and extraordinary rays. A meridional ray or tangential ray is a ray that is confined to the containing the systems optical axis. A skew ray is a ray that does not propagate in a plane that contains both the point and the optical axis. Such rays do not cross the optical axis anywhere, and are not parallel to it
5.
Sunlight
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Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is filtered through Earths atmosphere, and is obvious as daylight when the Sun is above the horizon, when the direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat. When it is blocked by clouds or reflects off other objects, the World Meteorological Organization uses the term sunshine duration to mean the cumulative time during which an area receives direct irradiance from the Sun of at least 120 watts per square meter. Other sources indicate an Average over the earth of 164 Watts per square meter over a 24 hour day. The ultraviolet radiation in sunlight has both positive and negative effects, as it is both a principal source of vitamin D3 and a mutagen. Sunlight takes about 8.3 minutes to reach Earth from the surface of the Sun. A photon starting at the center of the Sun and changing every time it encounters a charged particle would take between 10,000 and 170,000 years to get to the surface. Researchers may record sunlight using a sunshine recorder, pyranometer, or pyrheliometer, to calculate the amount of sunlight reaching the ground, both Earths elliptical orbit and the attenuation by Earths atmosphere have to be taken into account. In this formula dn–3 is used, because in modern times Earths perihelion, the closest approach to the Sun and, therefore, the value of 0.033412 is determined knowing that the ratio between the perihelion squared and the aphelion squared should be approximately 0.935338. The solar illuminance constant, is equal to 128×103 lx, the atmospheric extinction brings the number of lux down to around 100000. The total amount of energy received at ground level from the Sun at the zenith depends on the distance to the Sun and it is about 3. 3% higher than average in January and 3. 3% lower in July. In terms of energy, sunlight at Earths surface is around 52 to 55 percent infrared,42 to 43 percent visible, and 3 to 5 percent ultraviolet. At the top of the atmosphere, sunlight is about 30% more intense, having about 8% ultraviolet, direct sunlight has a luminous efficacy of about 93 lumens per watt of radiant flux. This is higher than the efficacy of most artificial lighting, which means using sunlight for illumination heats up a less than using most forms of artificial lighting. Multiplying the figure of 1050 watts per square metre by 93 lumens per watt indicates that bright sunlight provides an illuminance of approximately 98000 lux on a surface at sea level. The illumination of a surface will be considerably less than this if the Sun is not very high in the sky. Averaged over a day, the highest amount of sunlight on a horizontal surface occurs in January at the South Pole, dividing the irradiance of 1050 W/m2 by the size of the suns disk in steradians gives an average radiance of 15.4 MW per square metre per steradian. Multiplying this by π gives a limit to the irradiance which can be focused on a surface using mirrors,48.5 MW/m2
6.
Stratocumulus cloud
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Weak convective currents create shallow cloud layers because of drier, stable air above preventing continued vertical development. Most often, stratocumulus produce no precipitation, and when they do, however, these clouds are often seen at either the front or tail end of worse weather, so they may indicate storms to come, in the form of thunderheads or gusty winds. Stratocumulus clouds are same in appearance to altocumulus and are mistaken for such. This often does not apply when stratocumulus is of a broken, fractus form, stratocumulus is also often, though not always, darker in colour than altocumulus. Stratocumulus clouds are the type of cloud that can produce crepuscular rays. Thin stratocumulus clouds are often the cause of corona effects around the Moon at night. All stratocumulus subtypes are coded CL5 except when formed from free convective mother clouds or when formed separately from co-existing, stratocumulus Stratiformis are extensive flat but slightly lumpy sheets that show only minimal convective activity. Stratocumulus Lenticularis are separate flat elongated seed-shaped clouds and they are typical for polar countries or warmer climate during winter seasons. They also can be formed by winds passing hills or mountains, such as Foehn winds, stratocumulus Castellanus have stronger convective activity due to the presence of increasingly unstable air. They are distinct from other stratocumulus by puffy tower-like formations atop the cloud layer, stratocumulus castellanus may develop into cumulus congestus under auspicious conditions. Any showers from stratocumulus castellanus are not usually as heavy as those from cumulus congestus, stratocumulus Opacus is a dark layer of clouds covering entire sky without any break. However, the sheet is not completely uniform, so that separate cloud bases still can be seen. This is the main precipitating type, however any rain is usually light, if the cloud layer becomes grayer to the point when individual clouds can’t be distinguished, stratocumulus turn into stratus clouds. Stratocumulus Perlucidus is a layer of clouds with small spaces, appearing in irregular pattern. Stratocumulus Translucidus consist of groups of stratocumulus clouds, with a clear sky visible between them. Stratocumulus Undulatus clouds appear as nearly parallel waves, rolls or separate elongated clouds, stratocumulus Duplicatus clouds appear as stratocumulus clouds with two or more layers or sheets. Stratocumulus duplicatus is common on species lenticularis or lenticular cloud, stratocumulus Lacunosus clouds are very uncommon. They only occur there are localized downdrafts striking through the stratocumuliform cloud
7.
Perspectivity
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In geometry and in its applications to drawing, a perspectivity is the formation of an image in a picture plane of a scene viewed from a fixed point. The science of graphical perspective uses perspectivities to make images in proper proportion. According to Kirsti Andersen, the first author to describe perspectivity was Leon Alberti in his De Pictura. In English, Brook Taylor presented his Linear Perspective in 1715, the Lines producing that Projection, taken all together, are called the System of Rays. And when those Rays all pass thro’ one and same Point, a special symbol has been used to show that points X and Y are related by a perspectivity, X ⩞ Y. In this notation, to show that the center of perspectivity is P, using the language of functions, a central perspectivity with center P is a function f P, ↦ defined by f P = Y whenever P ∈ X Y. This map is an involution, that is, f P = X for all X ∈, the existence of a perspectivity means that corresponding points are in perspective. The dual concept, axial perspectivity, is the correspondence between the lines of two pencils determined by a projective range, the composition of two perspectivities is, in general, not a perspectivity. A perspectivity or a composition of two or more perspectivities is called a projectivity, theorem, Any projectivity from a projective range to itself can be written as the composition of three perspectivities. Theorem, A projectivity between two distinct ranges which fixes a point is a perspectivity. The bijective correspondence between points on two lines in a plane determined by a point of that plane not on either line has higher-dimensional analogues which will also be called perspectivities, let Sm and Tm be two distinct m-dimensional projective spaces contained in an n-dimensional projective space Rn. Let Pn−m−1 be a subspace of Rn with no points in common with either Sm or Tm. For each point X of Sm, the space L spanned by X and this correspondence fP is also called a perspectivity. The central perspectivity described above is the case with n =2 and m =1, let S2 and T2 be two distinct projective planes in a projective 3-space R3. This composition is a map of the points of S2 onto itself which preserves collinear points and is called a perspective collineation. Let φ be a perspective collineation of S2, each point of the line of intersection of S2 and T2 will be fixed by φ and this line is called the axis of φ. Let point P be the intersection of line OO* with the plane S2, P is also fixed by φ and every line of S2 that passes through P is stabilized by φ. P is called the center of φ, the restriction of φ to any line of S2 not passing through P is the central perspectivity in S2 with center P between that line and the line which is its image under φ. T
8.
Twilight
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Twilight is the illumination of the Earths lower atmosphere when the Sun itself is not directly visible because it is below the horizon. Twilight is produced by scattering in the upper atmosphere, illuminating the lower atmosphere so that the surface of the Earth is neither completely lit nor completely dark. The word twilight is also used to denote the periods of time when this illumination occurs, the further the Sun is below the horizon, the dimmer the twilight. When the Sun reaches 18 degrees below the horizon, the brightness is nearly zero. When the Sun again reaches 18 degrees below the horizon, nighttime becomes morning twilight, Twilight should not be confused with auroras, which can have a similar appearance in the night sky at high latitudes. By analogy with evening twilight, the word twilight is also used metaphorically, to imply that something is losing strength. For example, very old people may be said to be in the twilight of their lives, the collateral adjective for twilight is crepuscular which is sometimes applied to insects, fish, and mammals that are most active during that time. Twilight is defined according to the elevation angle θs, which is the position of the geometric center of the sun relative to the horizon. There are three established and widely accepted subcategories of twilight, civil twilight, nautical twilight, and astronomical twilight. Morning civil twilight begins when the center of the sun is 6° below the horizon. Evening civil twilight begins at sunset or when the center of the sun is 0°50′ below the horizon. In the United States military, the initialisms BMCT and EECT are used to refer to these periods, morning nautical twilight begins and evening nautical twilight ends when the geometric center of the sun reaches 12° below the horizon. Morning astronomical twilight begins and Evening astronomical twilight ends when the center of the Sun reaches 18° below the horizon. There are three established and widely accepted subcategories of twilight, civil twilight, nautical twilight, and astronomical twilight, under clear weather conditions, civil twilight approximates the limit at which solar illumination suffices for the human eye to clearly distinguish terrestrial objects. Enough sunlight renders artificial sources unnecessary for most outdoor activities, at civil dawn, the beginning of morning civil twilight, and at civil dusk, the end of evening civil twilight, sunlight clearly defines the horizon while the brightest stars and planets can appear. As observed from the Earth, sky-gazers know Venus, the brightest planet, law-makers have enshrined the concept of civil twilight. Such statutes typically use a period after sunset or before sunrise. The period may affect when pilots require a rating to fly aircraft
9.
Anticrepuscular rays
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Anticrepuscular rays or antisolar rays are similar to crepuscular rays, but seen opposite the sun in the sky. Anticrepuscular rays are near-parallel, but appear to converge at the point because of linear perspective. Anticrepuscular rays are most frequently visible near sunrise or sunset, crepuscular rays are usually much brighter than anticrepuscular rays. This is because for crepuscular rays, seen on the side of the sky as the sun. Although anticrepuscular rays appear to converge onto a point opposite the sun, the rays are in fact parallel, and their apparent convergence is to the vanishing point at infinity
10.
Florida
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Florida /ˈflɒrᵻdə/ is a state located in the southeastern region of the United States. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia, to the east by the Atlantic Ocean, Florida is the 22nd-most extensive, the 3rd-most populous, and the 8th-most densely populated of the U. S. states. Jacksonville is the most populous municipality in the state and is the largest city by area in the contiguous United States, the Miami metropolitan area is Floridas most populous urban area. The city of Tallahassee is the state capital, much of the state is at or near sea level and is characterized by sedimentary soil. The climate varies from subtropical in the north to tropical in the south, the American alligator, American crocodile, Florida panther, and manatee can be found in the Everglades National Park. It was a location of the Seminole Wars against the Native Americans. Today, Florida is distinctive for its large Cuban expatriate community and high population growth, the states economy relies mainly on tourism, agriculture, and transportation, which developed in the late 19th century. Florida is also renowned for amusement parks, orange crops, the Kennedy Space Center, Florida has attracted many writers such as Marjorie Kinnan Rawlings, Ernest Hemingway and Tennessee Williams, and continues to attract celebrities and athletes. It is internationally known for golf, tennis, auto racing, by the 16th century, the earliest time for which there is a historical record, major Native American groups included the Apalachee, the Timucua, the Ais, the Tocobaga, the Calusa and the Tequesta. Florida was the first part of the continental United States to be visited and settled by Europeans, the earliest known European explorers came with the Spanish conquistador Juan Ponce de León. Ponce de León spotted and landed on the peninsula on April 2,1513 and he named the region La Florida. The story that he was searching for the Fountain of Youth is a myth, in May 1539, Conquistador Hernando de Soto skirted the coast of Florida, searching for a deep harbor to land. He described seeing a wall of red mangroves spread mile after mile, some reaching as high as 70 feet. Very soon, many smokes appeared along the whole coast, billowing against the sky, the Spanish introduced Christianity, cattle, horses, sheep, the Spanish language, and more to Florida. Both the Spanish and French established settlements in Florida, with varying degrees of success, in 1559, Don Tristán de Luna y Arellano established a settlement at present-day Pensacola, making it the first attempted settlement in Florida, but it was abandoned by 1561. Spain maintained tenuous control over the region by converting the tribes to Christianity. The area of Spanish Florida diminished with the establishment of English settlements to the north, the English attacked St. Augustine, burning the city and its cathedral to the ground several times. Florida attracted numerous Africans and African-Americans from adjacent British colonies who sought freedom from slavery, in 1738, Governor Manuel de Montiano established Fort Gracia Real de Santa Teresa de Mose near St
