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Thermals
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 war ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliding
Gliding is a recreational activity and competitive air sports, air sport in which pilots fly glider aircraft, unpowered aircraft known as Glider (sailplane), gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word ''soaring'' is also used for the sport. Gliding as a sport began in the 1920s. Initially the objective was to increase the duration of flights but soon pilots attempted cross-country flights away from the place of launch. Improvements in aerodynamics and in the understanding of weather phenomena have allowed greater distances at higher average speeds. Long distances are now flown using any of the main sources of rising air: Ridge Lift, ridge lift, thermals and lee waves. When conditions are favourable, experienced pilots can now fly hundreds of kilometres before returning to their home airfields; occasionally flights of more than are achieved. Some competitive pilots fly in races around pre-defined course ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Column
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 density, 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 Power (physics), strength of thermals are influenced by the properties of the lower atmosphere (the ''troposphere''). When the air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hang Gliding
Hang gliding is an air sports, air sport or recreational activity in which a pilot flies a light, non-motorised, fixed-wing aircraft, fixed-wing heavier-than-air aircraft called a hang glider. Most modern hang gliders are made of an aluminium alloy or Composite material, composite frame covered with synthetic sailcloth to form a wing. Typically the pilot is in a harness suspended from the airframe, and controls the aircraft by shifting body weight in opposition to a control frame. Early hang gliders had a low lift-to-drag ratio, so pilots were restricted to gliding down small hills. By the 1980s this ratio significantly improved, and since then pilots have been able to Lift (soaring), soar for hours, gain thousands of meters of altitude in thermal updrafts, perform aerobatics, and glide cross-country for hundreds of kilometers. The Federation Aeronautique Internationale and national airspace governing organisations control some regulatory aspects of hang gliding. Obtaining the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lift (soaring)
Lift is a meteorological phenomenon used as an energy source by soaring aircraft and soaring birds. The most common human application of lift is in sport and recreation. The three air sports that use soaring flight are: gliding, hang gliding and paragliding. Energy can be gained by using rising air from four sources: * Thermals (where air rises due to heat), * Ridge lift, where air is forced upwards by a slope, * Wave lift, where a mountain produces a standing wave, * Convergence, where two air masses meet In dynamic soaring it is also possible to gain energy, though this uses differences in wind speeds rather than rising air. Thermals Thermals are columns of rising air that are formed on the ground through the warming of the surface by sunlight. If the air contains enough moisture, the water will condense from the rising air and form cumulus clouds. Thermal lift is often used by birds, such as raptors, vultures and storks. Although thermal lift was known to the Wright B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glider (sailplane)
A glider or sailplane is a type of glider aircraft used in the leisure activity and sport of gliding (also called soaring). This unpowered aircraft can use naturally occurring currents of rising air in the atmosphere to gain altitude. Sailplanes are aerodynamically streamlined and so can fly a significant distance forward for a small decrease in altitude. In North America the term 'sailplane' is also used to describe this type of aircraft. In other parts of the English-speaking world, the word 'glider' is more common. Types Gliders benefit from producing very low drag for any given amount of lift, and this is best achieved with long, thin wings, a slender fuselage and smooth surfaces with an absence of protuberances. Aircraft with these features are able to soar – climb efficiently in rising air produced by thermals or hills. In still air, sailplanes can glide long distances at high speed with a minimum loss of height in between. Sailplanes have rigid wings and either ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizontal Convective Rolls
Horizontal convective rolls, also known as horizontal roll vortices or cloud streets, are long rolls of counter-rotating air that are oriented approximately parallel to the ground in the planetary boundary layer. Although horizontal convective rolls, also known as cloud streets, have been clearly seen in satellite photographs for the last 30 years, their development is poorly understood, due to a lack of observational data. From the ground, they appear as rows of cumulus or cumulus-type clouds aligned parallel to the low-level wind. Research has shown these eddies to be significant to the vertical transport of momentum, heat, moisture, and air pollutants within the boundary layer. Cloud streets are usually more or less straight; rarely, cloud streets assume paisley patterns when the wind driving the clouds encounters an obstacle. Those cloud formations are known as von Kármán vortex streets. Characteristics Horizontal rolls are counter-rotating vortex rolls that are nea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulonimbus And Aviation
Numerous aviation accidents have occurred in the vicinity of thunderstorms due to the density of clouds. It is often said that the turbulence can be extreme enough inside a cumulonimbus to tear an aircraft into pieces, and even strong enough to hold a skydiver. However, this kind of accident is relatively rare. Moreover, the turbulence ''under'' a thunderstorm can be non-existent and is usually no more than moderate. Most thunderstorm-related crashes occur due to a stall (fluid mechanics), stall close to the ground when the pilot gets caught by surprise by a thunderstorm-induced wind shift. Moreover, aircraft damage caused by thunderstorms is rarely in the form of structural failure due to turbulence but is typically less severe and the consequence of secondary effects of thunderstorms (e.g., denting by hail or paint removal by high-speed flight in torrential rain). Cumulonimbus clouds are known to be extremely dangerous to air traffic, and it is recommended to avoid them as much ... [...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 flying and gliding animals, gliding animals and by aircraft such as glider (aircraft), 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 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 Patagium, gliding membrane of a gliding possum. However, gliding can be achieved with a flat (Camber (aerodynamics), uncambered) wing, as with a simple paper plane, or even with card-throwing. However, some aircraft with lifting body, lifting bod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unpowered Aircraft
Unpowered aircraft can remain airborne for a significant period of time without onboard propulsion. They can be classified as gliders, lighter-than-air balloons and tethered kites. In the case of kites, lift is obtained by tethering to a fixed or moving object, perhaps another kite, to obtain a flow of wind over the lifting surfaces. In the case of balloons, lift is obtained through inherent buoyancy and the balloon may or may not be tethered. Free balloon flight has little directional control. Gliding aircraft include sailplanes, hang gliders, and paragliders that have full directional control in free flight. History The first manned aircraft were kites, balloons and gliders. Man-lifting kites were used in ancient China and Japan, often as a punishment for prisoners. Unmanned hot-air balloons and toy "bamboo-copters" are also recorded in Chinese history. The first manned free flight was in a hot-air balloon built by the brothers Joseph-Michel and Jacques-Etienne Montgolf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, frost, larger polar regions of permafrost and ice caps (with seasonal snow), but no liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. It is half as wide as Earth or twice the Moon, with a diameter of , and has a surface area the size of all the dry land of Earth. Fine dust is prevalent across the surface and the atmosphere, being picked up and spread at the low Martian gravity even by the weak wind of the tenuous atmosphere. The terrain of Mars roughly follows a north-south ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar System" and "solar system" structures in theinaming guidelines document. The name is commonly rendered in lower case ('solar system'), as, for example, in the ''Oxford English Dictionary'' an''Merriam-Webster's 11th Collegiate Dictionary''. is the gravitationally bound Planetary system, system of the Sun and the objects that orbit it. It Formation and evolution of the Solar System, formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a hydrostatic equilibrium, balanced equilibrium by the thermonuclear fusion, fusion of hydrogen into helium at its stellar core, core, releasing this energy from its outer photosphere. As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
