Rain
- Browse Related Terms: FRZN, FZRA, Ice Storm, Mixed precipitation, R, RA, Rain Gauge, ZR
Rain
- Browse Related Terms: FRZN, FZRA, Ice Storm, Mixed precipitation, R, RA, Rain Gauge, ZR
RAdar DAta Processor II, attached to some WSR-57 and WSR-74 radar units. It automatically controls the tilt sequence and computes several radar-derived quantities at regular intervals, including VIL, storm tops, accumulated rainfall, etc.
- Browse Related Terms: Algorithm, Area Wide Hydrologic Prediction System, AUTOMATIC GAIN CONTROL, HDRAIN, Precipitation Processing System, RADAP II, Radar Coded Message, Severe Weather Probability, Three-Hour Rainfall Rate, VIL, WSR-57, WSR-74
Acronym for RAdio Detection And Ranging; a radio device or system for locating an object by means of ultrahigh-frequency radio waves reflected from the object and received, observed, and analyzed by the receiving part of the device in such a way that characteristics (as distance and direction) of the object may be determined.
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The straight line that a radar pulse travels along. As the radar beam gets further away from the radar, it gets wider and wider. In order for a precipitation target to be detected by the radar, it must fill the entire radar beam; therefore, the radar will have a difficult time detecting small showers and thunderstorms at a great distance from the radar.
- Browse Related Terms: Maximum Unambiguous Range, Maximum Unambiguous Velocity, Mean Doppler Velocity, Peak Pulse, Pulse, Pulse Repetition Frequency (PRF), Pulse Repetition Time (PRT), Pulse-Pair Processing, Radar Beam, Range Folding, Range Gate, Range Resolution, Receiver
This is an alphanumeric coded message which will be used in preparation of a national radar summary chart. It is automatically produced by the WSR-88D's Radar Product Generator (RPG) in 3 parts (reflectivities, storm motion, and echo tops).
- Browse Related Terms: Algorithm, Area Wide Hydrologic Prediction System, AUTOMATIC GAIN CONTROL, HDRAIN, Precipitation Processing System, RADAP II, Radar Coded Message, Severe Weather Probability, Three-Hour Rainfall Rate, VIL, WSR-57, WSR-74
The area of a fictitious, perfect reflector of electromagnetic waves (e.g., metal sphere) that would reflect the same amount of energy back to the radar as the actual target (e.g., lumpy snowflake).
- Browse Related Terms: Coherent Radar, dBZ, Echo, Ground Clutter, Minimum Discernible Signal, Monostatic Radar, Polarization Radar, Power, Pulse Radar, radar cross section, Range Normalization, Range Unfolding, Reflectivity Factor, Servo Loop, Sphere Calibration, Sun Pointing, transmitter, Z\/R Relationship
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An acronym for Radar Data Acquisition. The RDA is the hardware component of the NEXRAD system that consists of the radar antenna, transmitter, receiver, tower, and controlling computer. The RDA collects the unprocessed, analog voltages from the radar antenna and converts the signal to base reflectivity , base velocity, and spectrum width (in polar coordinate form). These "wide-band" products are transmitted to the RPG, which creates and disseminates end-user products. Also: The RDA is the origination point of the WSR-88D radar data that will be eventually used by the radar operator. This WSR-88D component group is made up of several subcomponents which generate and radiate radio frequency (RF) pulses, receive reflected energy from those pulses, and process this received energy into digital base data. The RDA is also the site of the first two of four data recording levels used by the WSR-88D to record and store radar data.
- Browse Related Terms: Hail Contamination, Hail Spike, Inch-Degrees, Partial Beam Filling, POH, Precipitation Mode, Probability of Hail, Radar Data Acquisition, Radar Mosaic, Radar Product Generator (RPG), Rainfall Estimates, SHARS, Storm Total Precipitation
Branch of meteorology that uses radars for weather observations and forecasts.
- Browse Related Terms: 1-2-3 Rule, AGFS, Complex Gale/Storm, CWFA, Developing Gale/Storm, FA, FCST, FOUS, Grids, High Seas Forecast, Marine Zone, NSSFC, OFSHR, PROGGED, Radar Meteorology, RAFC, RAFS, Red Flag Warning, TAF, Valid Time, ZFP
A radar product that combines information from multiple radars to give a regional or national view of reflectivity or precipitation. An individual NEXRAD radar is limited to a range of about 200 miles. Typically, a mosaic product is produced for regions spanning several hundreds to several thousands of miles. Mosaic products are produced by vendors external to the NEXRAD system.
- Browse Related Terms: Hail Contamination, Hail Spike, Inch-Degrees, Partial Beam Filling, POH, Precipitation Mode, Probability of Hail, Radar Data Acquisition, Radar Mosaic, Radar Product Generator (RPG), Rainfall Estimates, SHARS, Storm Total Precipitation
The RPG is the computer in the NEXRAD system that receives polar-coordinate base radar data from the RDA and processes these data into end-user products. Algorithms are utilized for pattern-recognition, rainfall estimation, computation of VIL and other products. The RPG communicates these products to end-users. A specific subset of available products is always generated for the NIDS vendors for distribution outside of the NWS, DoD, and FAA. Other products are generated by the RPG upon request from a PUP.
- Browse Related Terms: Hail Contamination, Hail Spike, Inch-Degrees, Partial Beam Filling, POH, Precipitation Mode, Probability of Hail, Radar Data Acquisition, Radar Mosaic, Radar Product Generator (RPG), Rainfall Estimates, SHARS, Storm Total Precipitation
Distance from the radar antenna. The WSR-88D radar has a range for velocity products out to 124 nautical miles and reflectivity products out to 248 nautical miles.
- Browse Related Terms: BASE DATA, BASE PRODUCTS, Base Reflectivity, Layer Composite Reflectivity Average, Layer Composite Reflectivity Maximum, OBSC, Radar Range, Range, Reflectivity Cross Section, Severe Weather Analysis, Spectrum Width Cross Section, Storm Relative Mean Radial Velocity Map, Storm Relative Mean Radial Velocity Regi, Storm Tracking Information, VAD, Weak Echo Region
The sum of all backscattering cross-sections (e.g., precipitation particles) in a pulse resolution volume divided by that volume. The radar reflectivity can be related to the radar reflectivity factor through the dielectric constant term |K|^2, and the radar wavelength.
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z = the sum (over i) of (N_i * D_i^6), where N_i is the number of drops of diameter D_i in a pulse resolution volume. Note that z may be expressed in linear or logarithmic units. The radar reflectivity factor is simply a more meteorologically meaningful way of expressing the radar reflectivity.
- Browse Related Terms: analog signal, ARR, DURN, Pingo, Pulse Duration, pulse length, pulse width, Radar Reflectivity Factor (z)
Component of motion toward or away from a given location. As "seen" by Doppler radar, it is the component of motion parallel to the radar beam. (The component of motion perpendicular to the beam cannot be seen by the radar. Therefore, strong winds blowing strictly from left to right or from right to left, relative to the radar, can not be detected.)
- Browse Related Terms: CALM, Coriolis force, Doppler Radar, Kinetic Energy, Radial Velocity, Spearhead Echo, Tilt, UVM, VRT MOTN
A measure of the intensity of the radiant energy flux emitted by a body in a given direction.
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Energy transport through electromagnetic waves. See shortwave radiation and longwave radiation.
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A fog that forms when outgoing longwave radiation cools the near-surface air below its dew point temperature.
- Browse Related Terms: Delta T, Dew Point Depression, DP, Haines Index, Isentropic Surface, Isodrosotherm, Isopleth, Isotherm, K-Index, Moisture Ridge, Nieve Penitente, Radiation Fog, Total-Totals Index
The four physical laws which fundamentally describe the behavior of blackbody radiation: Kirchhoff's law, Planck's law, Stefan-Boltzmann law and Wien's displacement law.
- Browse Related Terms: Blackbody, Blackbody Radiation, Diurnal Cycles, Freeze, Frost, FRST, Infrared Satellite Imagery, Outgoing Longwave Radiation, Radiation Laws
The cooling of the Earth's surface. At night, the Earth suffers a net heat loss to space due to terrestrial cooling. This is more pronounced when you have a clear sky.
- Browse Related Terms: Air, Climate System, Conjugate Points, Downwelling Radiation, Equinox, Free Atmosphere, Ground Heat Flux, Latent Heat Flux, Lightning Discharge, Mesoclimate, Nacreous Clouds, Net All-Wave Radiation, Noctilucent Clouds, Radiational Cooling, Rain, Rotation, Sensible Heat Flux, Surface Energy Budget, Surface-based Convection, Visible Satellite Imagery