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Raindrop Size Distribution
The raindrop size distribution (''DSD''), or granulometry of rain, is the distribution of the number of raindrops according to their diameter (D). Three processes account for the formation of drops: water vapor condensation, accumulation of small drops on large drops and collisions between sizes. According to the time spent in the cloud, the vertical movement in it and the ambient temperature, the drops that have a very varied history and a distribution of diameters from a few micrometers to a few millimeters. Definition In general, the drop size distribution is represented as a truncated gamma function for diameter zero to the maximum possible size of rain droplets. The number of drop with diameter D is therefore : N(D) = N_0 D^\mu e^ with N_0, \mu and \lambda as constants. Marshall-Palmer distribution The most well-known study about raindrop size distribution is from Marshall and Palmer done at McGill University in Montréal in 1948. They used stratiform rain with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DSD Marshall-Palmer
DSD may refer to: Medical and Research * Detrusor sphincter dyssynergia, disorder of urination * Disorders of sex development, differences of sex differentiation * Definitive Screening Design, an experimental design for multiple variables Technology * Data structure diagram of a data model * Direct Stream Digital, Sony and Philips digital recording trademark * Document Structure Description, a schema language for describing valid XML Organizations * Defence Signals Directorate, an Australian intelligence agency * Department for Social Development * Drainage Services Department, Hong Kong * Davis School District, Utah * Delaware School for the Deaf Government * United States District Court for the District of South Dakota, abbreviation in case decisions * Downing Street Declaration, by UK PM and Irish Taoiseach * New Zealand Distinguished Service Decoration, a medal awarded by the New Zealand Defence Force Media * ''Do Something Different'', a British CBBC television show * D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Profiler
A wind profiler is a type of weather observing equipment that uses radar or sound waves ( SODAR) to detect the wind speed and direction at various elevations above the ground. Readings are made at each kilometer above sea level, up to the extent of the troposphere (i.e., between 8 and 17 km above mean sea level). Above this level there is inadequate water vapor present to produce a radar "bounce." The data synthesized from wind direction and speed is very useful to meteorological forecasting and timely reporting for flight planning. A twelve-hour history of data is available through NOAA websites. Principle In a typical implementation, the radar or sodar can sample along each of five beams: one is aimed vertically to measure vertical velocity, and four are tilted off vertical and oriented orthogonal to one another to measure the horizontal components of the air's motion. A profiler's ability to measure winds is based on the assumption that the turbulent eddies that induce sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Water Content
The liquid water content (LWC) is the measure of the mass of the water in a cloud in a specified amount of dry air. It is typically measured per volume of air (g/m3) or mass of air (g/kg) (Bohren, 1998). This variable is important in figuring out which types of clouds are likely to form and is strongly linked to three other cloud microphysical variables: the cloud drop effective radius, the cloud drop number concentration, and the cloud drop size distribution (Wallace, 2006). Being able to determine the cloud formations that are likely to occur is extremely useful for weather forecasting as cumulonimbus clouds are related to thunderstorms and heavy rain whereas cirrus clouds are not directly associated with precipitation. Characteristics The liquid water content of a cloud varies significantly depending on the type of clouds present in the atmosphere at a given location. The classification of the cloud is highly related to the liquid water content as well as the origin of the cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloud Drop Effective Radius
The cloud drop effective radius (alternatively cloud effective radius or simply effective radius when in context) is a weighted mean of the size distribution of cloud droplets. The term was defined in 1974 by James E. Hansen and Larry Travis as the ratio of the third to the second moment of a droplet size distribution to aid in the inversion of remotely sensed data. Physically, it is an area weighted radius of the cloud drop particles. Mathematically, this can be expressed as :r_e = \dfrac. The global effective particle radius has different values for water and ice clouds: the former is around 14 μm, whereas for ice it is around 25 μm. Studies also indicate that the effective cloud droplet radius is larger over oceans than over ground by 15%-20%. By contrast, the difference in the ice particle size over land and oceans is much smaller (only 5%). See also *Liquid water content *Raindrop size distribution The raindrop size distribution (''DSD''), or granulometry of rain, is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Oceanic And Atmospheric Administration
The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditions, charts the seas, conducts deep sea exploration, and manages fishing and protection of marine mammals and endangered species in the U.S. exclusive economic zone. Purpose and function NOAA's specific roles include: * ''Supplying Environmental Information Products''. NOAA supplies to its customers and partners information pertaining to the state of the oceans and the atmosphere, such as weather warnings and forecasts via the National Weather Service. NOAA's information services extend as well to climate, ecosystems, and commerce. * ''Providing Environmental Stewardship Services''. NOAA is a steward of U.S. coastal and marine environments. In coordination with federal, state, local, tribal and international authorities, NOAA manages the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nimbostratus Cloud
A nimbostratus cloud is a multi-level, amorphous, nearly uniform and often dark grey cloud that usually produces continuous rain, snow or sleet but no lightning or thunder. in the Oxford Dictionaries Online Although it is usually a low-based cloud, it actually forms most commonly in the middle level of the troposphere and then spreads vertically into the low and high levels. Nimbostratus usually produces precipitation over a wide area. ''Nimbo-'' is from the Latin word ''nimbus'', which denotes cloud or halo. Downward-growing nimbostratus can have the same vertical extent as most large upward-growing cumulus, but its horizontal extent tends to be even greater. Appearance Nimbostratus has a diffuse |
Atmospheric Convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes. Overview There are a few general archetypes of atmospheric instability that are used to explain convection (or lack thereof). A necessary (but not sufficient) condition for convection is that the environmental lapse rate (the rate of decrease of temperature with height) is steeper than the lapse rate experienced by a rising parcel of air. When this condition is met, upward-displaced air parcels can become buoyant and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Météo-France
Météo-France is the French national meteorological service. Organisation The organisation was established by decree in June 1993 and is a department of the Ministry of Transportation. It is headquartered in Paris but many domestic operations have been decentralised to Toulouse. Its budget of around €300 million is funded by state grants, aeronautic royalties and sale of commercial services. Météo-France has a particularly strong international presence, and is the French representative at the World Meteorological Organization. The organisation is a leading member of EUMETSAT, responsible for the procurement of Meteosat weather satellites. It is also member of the Institut au service du spatial, de ses applications et technologies. It also a critical national weather service member of the ECMWF and hosts one of two major centres of the IFS numerical weather prediction model widely used worldwide. Worldwide In addition to its operations in metropolitan France, the agen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permittivity
In electromagnetism, the absolute permittivity, often simply called permittivity and denoted by the Greek letter ''ε'' ( epsilon), is a measure of the electric polarizability of a dielectric. A material with high permittivity polarizes more in response to an applied electric field than a material with low permittivity, thereby storing more energy in the material. In electrostatics, the permittivity plays an important role in determining the capacitance of a capacitor. In the simplest case, the electric displacement field D resulting from an applied electric field E is :\mathbf = \varepsilon \mathbf. More generally, the permittivity is a thermodynamic function of state. It can depend on the frequency, magnitude, and direction of the applied field. The SI unit for permittivity is farad per meter (F/m). The permittivity is often represented by the relative permittivity ''ε''r which is the ratio of the absolute permittivity ''ε'' and the vacuum permittivity ''ε''0 :\kappa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectivity
The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic structure of the material to the electromagnetic field of light, and is in general a function of the frequency, or wavelength, of the light, its polarization, and the angle of incidence. The dependence of reflectance on the wavelength is called a ''reflectance spectrum'' or ''spectral reflectance curve''. Mathematical definitions Hemispherical reflectance The ''hemispherical reflectance'' of a surface, denoted , is defined as R = \frac, where is the radiant flux ''reflected'' by that surface and is the radiant flux ''received'' by that surface. Spectral hemispherical reflectance The ''spectral hemispherical reflectance in frequency'' and ''spectral hemispherical reflectance in wavelength'' of a surface, denoted and respectively, are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disdrometer
A disdrometer is an instrument used to measure the drop size distribution and velocity of falling hydrometeors. Some disdrometers can distinguish between rain, graupel, and hail. The uses for disdrometers are numerous. They can be used for traffic control, scientific examination, airport observation systems, and hydrology. The latest disdrometers employ microwave or laser technologies. 2D video disdrometers can be used to analyze individual raindrops and snowflakes. See also * Rain gauge * Snow gauge A snow gauge is a type of instrument used by meteorologists and hydrologists to gather and measure the amount of solid precipitation (as opposed to liquid precipitation, which is measured by a rain gauge) over a set period of time. History The ... References Measuring instruments Meteorological instrumentation and equipment Hydrology instrumentation {{Climate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disdrometer
A disdrometer is an instrument used to measure the drop size distribution and velocity of falling hydrometeors. Some disdrometers can distinguish between rain, graupel, and hail. The uses for disdrometers are numerous. They can be used for traffic control, scientific examination, airport observation systems, and hydrology. The latest disdrometers employ microwave or laser technologies. 2D video disdrometers can be used to analyze individual raindrops and snowflakes. See also * Rain gauge * Snow gauge A snow gauge is a type of instrument used by meteorologists and hydrologists to gather and measure the amount of solid precipitation (as opposed to liquid precipitation, which is measured by a rain gauge) over a set period of time. History The ... References Measuring instruments Meteorological instrumentation and equipment Hydrology instrumentation {{Climate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
