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Bird Flight
Bird flight is the primary mode of locomotion used by most bird species in which birds take off and fly. Flight assists birds with feeding, breeding, avoiding predators, and migrating. Bird flight is one of the most complex forms of locomotion in the animal kingdom. Each facet of this type of motion, including hovering, taking off, and landing, involves many complex movements. As different bird species adapted over millions of years through evolution for specific environments, prey, predators, and other needs, they developed specializations in their wings, and acquired different forms of flight. Various theories exist about how bird flight evolved, including flight from falling or gliding (the ''trees down'' hypothesis), from running or leaping (the ''ground up'' hypothesis), from ''wing-assisted incline running'' or from '' proavis'' (pouncing) behavior. Basic mechanics of bird flight Lift, Drag and Thrust The fundamentals of bird flight are similar to those of aircraft, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Domestic Pigeon Flock
Domestic may refer to: In the home * Anything relating to the human home or family ** A domestic animal, one that has undergone domestication ** A domestic appliance, or home appliance ** A domestic partnership ** Domestic science, sometimes called family and consumer science ** Domestic violence ** A domestic worker In the state * Domestic affairs, matters relating to the internal government of a Sovereign state * Domestic airport * Domestic flight * Domestic policy, the internal policy of a state Other * Domestic, Indiana, an unincorporated community in Wells County * ''Domestikos'' ( en, the Domestic), a Byzantine title ** Domestic of the Schools, commander-in-chief of the Byzantine army in the 9th-11th centuries * Domestic (film), ''Domestic'' (film), a 2012 Romanian comedy film See also * Domestic discipline (other) * Housekeeper (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wingtip Vortices
Wingtip vortices are circular patterns of rotating air left behind a wing as it generates lift.Clancy, L.J., ''Aerodynamics'', section 5.14 One wingtip vortex trails from the tip of each wing. Wingtip vortices are sometimes named ''trailing'' or ''lift-induced vortices'' because they also occur at points other than at the wing tips. Indeed, vorticity is trailed at any point on the wing where the lift varies span-wise (a fact described and quantified by the lifting-line theory); it eventually rolls up into large vortices near the wingtip, at the edge of flap devices, or at other abrupt changes in wing planform. Wingtip vortices are associated with induced drag, the imparting of downwash, and are a fundamental consequence of three-dimensional lift generation. Careful selection of wing geometry (in particular, wingspan), as well as of cruise conditions, are design and operational methods to minimize induced drag. Wingtip vortices form the primary component of wake turbulence. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hummingbird Hovering In Mid-air
Hummingbirds are birds native to the Americas and comprise the biological family Trochilidae. With about 361 species and 113 genera, they occur from Alaska to Tierra del Fuego, but the vast majority of the species are found in the tropics around the equator. They are small birds, with most species measuring in length. The smallest extant hummingbird species is the bee hummingbird, which weighs less than . The largest hummingbird species is the giant hummingbird, weighing . They are specialized for feeding on flower nectar, but all species also consume flying insects or spiders. Hummingbirds split from their sister group, the swifts and treeswifts, around 42 million years ago. The common ancestor of extant hummingbirds is estimated to have lived 22 million years ago in South America. They are known as hummingbirds because of the humming sound created by their beating wings, which flap at high frequencies audible to humans. They hover in mid-air at rapid wing-flapping rates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calypte Anna, San Francisco
''Calypte'' is a genus of hummingbirds. It consists of two species found in western North America. Taxonomy The genus ''Calypte'' was introduced in 1856 by the English ornithologist John Gould. The type species was subsequently designated as Costa's hummingbird. Gould did not explain the derivation of the genus name but it is probably from the Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ... ''kaluptrē'' meaning "woman’s veil" or "head-dress" (from ''kaluptō'' meaning "to cover"). The genus now contains two species. Species References *"National Geographic". ''Field Guide to the Birds of North America''. . Hummingbirds Bird genera {{hummingbird-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Of Attack
In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is moving. Angle of attack is the angle between the body's reference line and the oncoming flow. This article focuses on the most common application, the angle of attack of a wing or airfoil moving through air. In aerodynamics, angle of attack specifies the angle between the chord line of the wing of a fixed-wing aircraft and the vector representing the relative motion between the aircraft and the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be definable, so an alternate reference line is simply defined. Often, the chord line of the root of the wing is chosen as the reference line. Another choice is to use a horizontal line on the fuselage as the reference line (and also as the longitudinal axis). Some aut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weight
In science and engineering, the weight of an object is the force acting on the object due to gravity. Some standard textbooks define weight as a Euclidean vector, vector quantity, the gravitational force acting on the object. Others define weight as a scalar quantity, the magnitude of the gravitational force. Yet others define it as the magnitude of the reaction (physics), reaction force exerted on a body by mechanisms that counteract the effects of gravity: the weight is the quantity that is measured by, for example, a spring scale. Thus, in a state of free fall, the weight would be zero. In this sense of weight, terrestrial objects can be weightless: ignoring Drag (physics), air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, would be weightless. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton (unit), newton. For example, an object with a mass of one kilogram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrust
Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that system. The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust. Force, and thus thrust, is measured using the International System of Units (SI) in newtons (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second. In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as static thrust. Examples A fixed-wing aircraft propulsion system generates forward thrust when air is pushed in the direction opposite to flight. This can be done by different means such as the spinning blades of a propeller, the propelling jet of a jet engine, or by ejecting hot gases from a rocket ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. Thermals on Earth The Sun warms the ground, which in turn warms the air directly above. The warm air near the surface expands, becoming less dense than the surrounding air. The lighter air rises and cools due to its expansion in the lower pressure at higher altitudes. It stops rising when it has cooled to the same temperature, thus density, as the surrounding air. Associated with a thermal is a downward flow surrounding the thermal column. The downward-moving exterior is caused by colder air being displaced at the top of the thermal. The size and strength of thermals are influenced by the properties of the lower atmosphere (the ''troposphere''). When the air is cold, bubbles of warm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Draft
In meteorology, an updraft is a small-scale current of rising air, often within a cloud. Overview Localized regions of warm or cool air will exhibit vertical movement. A mass of warm air will typically be less dense than the surrounding region, and so will rise until it reaches air that is either warmer or less dense than itself. The converse will occur for a mass of cool air, and is known as subsidence. This movement of large volumes of air, especially when regions of hot, wet air rise, can create large clouds, and is the central source of thunderstorms. Drafts can also be conceived by low or high pressure regions. A low pressure region will attract air from the surrounding area, which will move towards the center and then rise, creating an updraft. A high pressure region will attract air from the surrounding area, which will move towards the center and sink, spawning a downdraft. Updrafts and downdrafts, along with wind shear in general, are a major contributor to airplane cras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliding (flight)
Gliding flight is heavier-than-air flight without the use of thrust; the term volplaning also refers to this mode of flight in animals. It is employed by gliding animals and by aircraft such as gliders. This mode of flight involves flying a significant distance horizontally compared to its descent and therefore can be distinguished from a mostly straight downward descent like with a round parachute. Although the human application of gliding flight usually refers to aircraft designed for this purpose, most powered aircraft are capable of gliding without engine power. As with sustained flight, gliding generally requires the application of an airfoil, such as the wings on aircraft or birds, or the gliding membrane of a gliding possum. However, gliding can be achieved with a flat ( uncambered) wing, as with a simple paper plane, or even with card-throwing. However, some aircraft with lifting bodies and animals such as the flying snake can achieve gliding flight without any wings b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lesser Flamingo
The lesser flamingo (''Phoeniconaias minor'') is a species of flamingo occurring in sub-Saharan Africa and western India. Birds are occasionally reported from further north, but these are generally considered Vagrancy (biology), vagrants. Characteristics The lesser flamingo is the smallest species of flamingo, though it is a tall and large bird by most standards. The species can weigh from . The standing height is around . The total length (from beak to tail) and wingspan are in the same range of measurements, from . Most of the plumage is pinkish white. The clearest difference between this species and the greater flamingo, the only other Old World species of flamingo, is the much more extensive black on the bill. Size is less helpful unless the species are together, since the sexes of each species also differ in height. The extinct species ''Phoeniconaias proeses'' in the same genus, from the Pliocene of Australia, is thought to have been even smaller. The lesser flamingo may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
