1.
Meteorology
–
Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not occur until the 18th century, the 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data, Meteorological phenomena are observable weather events that are explained by the science of meteorology. Different spatial scales are used to describe and predict weather on local, regional, Meteorology, climatology, atmospheric physics, and atmospheric chemistry are sub-disciplines of the atmospheric sciences. Meteorology and hydrology compose the interdisciplinary field of hydrometeorology, the interactions between Earths atmosphere and its oceans are part of a coupled ocean-atmosphere system. Meteorology has application in diverse fields such as the military, energy production, transport, agriculture. The word meteorology is from Greek μετέωρος metéōros lofty, high and -λογία -logia -logy, varāhamihiras classical work Brihatsamhita, written about 500 AD, provides clear evidence that a deep knowledge of atmospheric processes existed even in those times. In 350 BC, Aristotle wrote Meteorology, Aristotle is considered the founder of meteorology. One of the most impressive achievements described in the Meteorology is the description of what is now known as the hydrologic cycle and they are all called swooping bolts because they swoop down upon the Earth. Lightning is sometimes smoky, and is then called smoldering lightning, sometimes it darts quickly along, at other times, it travels in crooked lines, and is called forked lightning. When it swoops down upon some object it is called swooping lightning, the Greek scientist Theophrastus compiled a book on weather forecasting, called the Book of Signs. The work of Theophrastus remained a dominant influence in the study of weather, in 25 AD, Pomponius Mela, a geographer for the Roman Empire, formalized the climatic zone system. According to Toufic Fahd, around the 9th century, Al-Dinawari wrote the Kitab al-Nabat, ptolemy wrote on the atmospheric refraction of light in the context of astronomical observations. St. Roger Bacon was the first to calculate the size of the rainbow. He stated that a rainbow summit can not appear higher than 42 degrees above the horizon, in the late 13th century and early 14th century, Kamāl al-Dīn al-Fārisī and Theodoric of Freiberg were the first to give the correct explanations for the primary rainbow phenomenon. Theoderic went further and also explained the secondary rainbow, in 1716, Edmund Halley suggested that aurorae are caused by magnetic effluvia moving along the Earths magnetic field lines. In 1441, King Sejongs son, Prince Munjong, invented the first standardized rain gauge and these were sent throughout the Joseon Dynasty of Korea as an official tool to assess land taxes based upon a farmers potential harvest. In 1450, Leone Battista Alberti developed a swinging-plate anemometer, and was known as the first anemometer, in 1607, Galileo Galilei constructed a thermoscope
2.
Turbulence
–
Turbulence or turbulent flow is a flow regime in fluid dynamics characterized by chaotic changes in pressure and flow velocity. It is in contrast to a flow regime, which occurs when a fluid flows in parallel layers. Turbulence is caused by kinetic energy in parts of a fluid flow. For this reason turbulence is easier to create in low viscosity fluids, in general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases. This would increase the energy needed to pump fluid through a pipe, however this effect can also be exploited by such as aerodynamic spoilers on aircraft, which deliberately spoil the laminar flow to increase drag and reduce lift. The onset of turbulence can be predicted by a constant called the Reynolds number. However, turbulence has long resisted detailed physical analysis, and the interactions within turbulence creates a complex situation. Richard Feynman has described turbulence as the most important unsolved problem of classical physics, smoke rising from a cigarette is mostly turbulent flow. However, for the first few centimeters the flow is laminar, the smoke plume becomes turbulent as its Reynolds number increases, due to its flow velocity and characteristic length increasing. If the golf ball were smooth, the boundary layer flow over the front of the sphere would be laminar at typical conditions. However, the layer would separate early, as the pressure gradient switched from favorable to unfavorable. To prevent this happening, the surface is dimpled to perturb the boundary layer. This results in higher skin friction, but moves the point of boundary layer separation further along, resulting in form drag. The flow conditions in industrial equipment and machines. The external flow over all kind of such as cars, airplanes, ships. The motions of matter in stellar atmospheres, a jet exhausting from a nozzle into a quiescent fluid. As the flow emerges into this external fluid, shear layers originating at the lips of the nozzle are created and these layers separate the fast moving jet from the external fluid, and at a certain critical Reynolds number they become unstable and break down to turbulence. Biologically generated turbulence resulting from swimming animals affects ocean mixing, snow fences work by inducing turbulence in the wind, forcing it to drop much of its snow load near the fence
3.
Radiosonde
–
Modern radiosondes measure or calculate the following variables, altitude, pressure, temperature, relative humidity, wind, cosmic ray readings at high altitude and geographical position. Radiosondes measuring ozone concentration are known as ozonesondes, radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz. A radiosonde whose position is tracked as it ascends to give wind speed, most radiosondes have radar reflectors and are technically rawinsondes. A radiosonde that is dropped from an airplane and falls, rather than being carried by a balloon is called a dropsonde, radiosondes are an essential source of meteorological data, and hundreds are launched all over the world daily. This proved to be difficult because the kites were linked to the ground and were difficult to manoeuvre in gusty conditions. Furthermore, the sounding was limited to low altitudes because of the link to the ground, gustave Hermite and Georges Besançon, from France, were the first in 1892 to use a balloon to fly the meteograph. In 1898, Léon Teisserenc de Bort organized at the Observatoire de Météorologie Dynamique de Trappes the first regular use of these balloons. Data from these launches showed that the temperature lowered with height up to an altitude, which varied with the season. De Borts discovery of the tropopause and stratosphere was announced in 1902 at the French Academy of Sciences, other researchers, like Richard Aßmann and William Henry Dines, were working at the same times with similar instruments. In 1924, Colonel William Blaire in the U. S. Signal Corps did the first primitive experiments with weather measurements from balloon, the first true radiosonde that sent precise encoded telemetry from weather sensors was invented in France by Robert Bureau. Bureau coined the name radiosonde and flew the first instrument on January 7,1929, developed independently a year later, Pavel Molchanov flew a radiosonde on January 30,1930. Molchanovs design became a popular standard because of its simplicity and because it converted sensor readings to Morse code, working with a modified Molchanov sonde, Sergey Vernov was the first to use radiosondes to perform cosmic ray readings at high altitude. On April 1,1935, he took measurements up to 13.6 km using a pair of Geiger counters in a circuit to avoid counting secondary ray showers. The sondes were tracked for two days, a rubber or latex balloon filled with either helium or hydrogen lifts the device up through the atmosphere. The maximum altitude to which the balloon ascends is determined by the diameter, balloon sizes can range from 100 to 3,000 g. As the balloon ascends through the atmosphere, the pressure decreases, eventually, the balloon will expand to the extent that its skin will break, terminating the ascent. An 800 g balloon will burst at about 21 km, after bursting, a small parachute on the radiosondes support line carries it to Earth. A typical radiosonde flight lasts 60 to 90 minutes, one radiosonde from Clark Air Base, Philippines, reached an altitude of 155,092 ft
4.
Supercell
–
A supercell is a thunderstorm that is characterized by the presence of a mesocyclone, a deep, persistently rotating updraft. For this reason, these storms are referred to as rotating thunderstorms. Of the four classifications of thunderstorms, supercells are the overall least common and have the potential to be the most severe, supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometres away. Supercells are often put into three types, Classic, Low-precipitation, and High-precipitation. LP supercells are found in climates that are more arid, such as the high plains of the United States. Supercells are usually isolated from other thunderstorms, although they can sometimes be embedded in a squall line. Typically, supercells are found in the sector of a low pressure system propagating generally in a north easterly direction in line with the cold front of the low pressure system. Because they can last for hours, they are known as quasi-steady-state storms, supercells have the capability to deviate from the mean wind. If they track to the right or left of the wind, they are said to be right-movers or left-movers. Supercells can sometimes develop two separate updrafts with opposing rotations, which splits the storm into two supercells, one left-mover and one right-mover, supercells can be any size – large or small, low or high topped. They usually produce copious amounts of hail, torrential rainfall, strong winds, supercells are one of the few types of clouds that typically spawn tornadoes within the mesocyclone, although only 30% or fewer do so. Supercells can occur anywhere in the world under the weather conditions. The first storm to be identified as the type was the Wokingham storm over England. Browning did the work that was followed up by Lemon. Supercells occur occasionally in many other regions, including eastern China. The areas with highest frequencies of supercells are similar to those with the most occurrences of tornadoes, see tornado climatology and Tornado Alley. The current conceptual model of a supercell was described in Severe Thunderstorm Evolution and Mesocyclone Structure as Related to Tornadogenesis by Leslie R. Lemon, supercells derive their rotation through tilting of horizontal vorticity caused by wind shear. Strong updrafts lift the air turning about an axis and cause this air to turn about a vertical axis
5.
Richardson number
–
The Richardson number is named after Lewis Fry Richardson. The Richardson number, or one of several variants, is of importance in weather forecasting and in investigating density and turbidity currents in oceans, lakes. If the Richardson number is less than unity, buoyancy is unimportant in the flow. If it is greater than unity, buoyancy is dominant. If the Richardson number is of order unity, then the flow is likely to be buoyancy-driven, in aviation, the Richardson number is used as a rough measure of expected air turbulence. A lower value indicates a degree of turbulence. Values in the range 10 to 0.1 are typical, in thermal convection problems, Richardson number represents the importance of natural convection relative to the forced convection. The Richardson number can also be expressed by using a combination of the Grashof number and Reynolds number, R i = G r R e 2. Typically, the convection is negligible when Ri <0.1, forced convection is negligible when Ri >10. It may be noted that usually the forced convection is large relative to natural convection except in the case of extremely low forced flow velocities, in the design of water filled thermal energy storage tanks, the Richardson number can be useful. In oceanography, the Richardson number has a general form which takes stratification into account. R i = N2 /2 where N is the Brunt–Väisälä frequency, the Richardson number defined above is always considered positive. A negative value of N² indicates unstable density gradients with active convective overturning, under such circumstances the magnitude of negative Ri is not generally of interest. It can be shown that Ri < 1/4 is a condition for velocity shear to overcome the tendency of a stratified fluid to remain stratified. When Ri is large, turbulent mixing across the stratification is generally suppressed
6.
Atmospheric thermodynamics
–
Atmospheric thermodynamics is the study of heat-to-work transformations that take place in the earths atmosphere and manifest as weather or climate. Atmospheric thermodynamic diagrams are used as tools in the forecasting of storm development, the atmosphere is an example of a non-equilibrium system. Those dynamics are modified by the force of the pressure gradient, the tools used include the law of energy conservation, the ideal gas law, specific heat capacities, the assumption of isentropic processes, and moist adiabatic processes. Considerations of moist air and cloud theories typically involve various temperatures, such as equivalent potential temperature, wet-bulb and virtual temperatures. Connected areas are energy, momentum, and mass transfer, turbulence interaction between air particles in clouds, convection, dynamics of tropical cyclones, and large scale dynamics of the atmosphere and these equations form a basis for the numerical weather and climate predictions. In 1873, thermodynamicist Willard Gibbs published Graphical Methods in the Thermodynamics of Fluids and these sorts of foundations naturally began to be applied towards the development of theoretical models of atmospheric thermodynamics which drew the attention of the best minds. Papers on atmospheric thermodynamics appeared in the 1860s that treated such topics as dry, in 1884 Heinrich Hertz devised first atmospheric thermodynamic diagram. In 1911 von Alfred Wegener published a book Thermodynamik der Atmosphäre, Leipzig, from here the development of atmospheric thermodynamics as a branch of science began to take root. The term atmospheric thermodynamics, itself, can be traced to Frank W. Verys 1919 publication, by the late 1970s various textbooks on the subject began to appear. Today, atmospheric thermodynamics is an part of weather forecasting. The thermodynamic efficiency of the Hadley system, considered as an engine, has been relatively constant over the 1979~2010 period. Parcels of air traveling close to the sea surface take up heat and water vapor, the rising air, and condensation, produces circulatory winds that are propelled by the Coriolis force, which whip up waves and increase the amount of warm moist air that powers the cyclone. Both a decreasing temperature in the upper troposphere or a temperature of the atmosphere close to the surface will increase the maximum winds observed in hurricanes. When applied to hurricane dynamics it defines a Carnot heat engine cycle, the Clausius–Clapeyron relation shows how the water-holding capacity of the atmosphere increases by about 8% per Celsius increase in temperature. This water-holding capacity, or equilibrium vapor pressure, can be approximated using the August-Roche-Magnus formula e s =6.1094 exp and this shows that when atmospheric temperature increases the absolute humidity should also increase exponentially. An air-sea interaction theory for tropical cyclones, J. Atmos
