radarAcronym for RAdio Detection And Ranging; a radio device or system for locating an object by means of ultrahigh-frequency radio waves reflected from the…
radar dopplerThe power spectrum and moments of the radar signal expressed as a function of Doppler frequency or Doppler velocity.
Radar ReflectivityThe sum of all backscattering cross-sections (e.g., precipitation particles) in a pulse resolution volume divided by that volume.
radianceA measure of the intensity of the radiant energy flux emitted by a body in a given direction.
Radiation(RAY-dee-AY-shun) Energy released in the form of particle or electromagnetic waves.
Radiative ForcingRadiative forcing is the change in the net vertical irradiance (expressed in Watts per square metre: Wm-2) at the tropopause due to an internal change or…
radiative heating rateThe heating rate due to the divergence of long and shortwave radiative flux; this is a calculated quantity using the state of the atmospheric and…
radiocarbon (<sup>14</sup>C)a radioactive isotope of carbon. Since it decays with a half-life of 5570 years, its concentration in organic materials relative to the stable…
radiocarbon datingthe process of providing an absolute age for a material by using measurements of the amount of radiocarbon it still contains.
RadiosondeAn instrument that is carried aloft by a balloon to send back information on atmospheric temperature, pressure and humidity by means of a small…
RainPrecipitation that falls to earth in drops more than 0.5 mm in diameter.
rain gageA device, usually a cylindrical container, for measuring rainfall.
RangelandLand on which the native vegetation, climax, or natural potential consists predominately of grasses, grasslike plants, forbs, or shrubs.
RawinsondeA radiosonde that is tracked to measure winds.
RecyclingThe process of converting materials that are no longer useful as designed or intended into a new product.
reflectionThe process whereby radiation (or other waves) incident upon a surface is directed back into the medium through which it traveled.
reflectivity (dBZ)A measure of the returned power, which is sensitive to the size and number of hydrometeors (i.e., the particle size spectra).
ReforestationPlanting of forests on lands that have previously contained forests but that have been converted to some other use.
RefractionThe change in direction of a ray of light when it passes through one media to another with differing optical densities.
relative datingthe process of determining the order in which certain events occurred or certain materials were formed.
Relative HumidityA measure of the percent of moisture actually in the air compared with what would be in it if it were fully saturated at that temperature.
Renewable EnergyEnergy derived from resources that are regenerative or for all practical purposes can not be depleted.
Residence TimeThe average time spent in a reservoir by an individual atom or molecule. With respect to greenhouse gases, residence time usually refers to how long a…
Residual fuel oilHeavy fuel oil produced from the residue in the fractional distillation process rather than from the distilled fractions. No.
Residual Layerthe elevated portion of a convective boundary layer that remains after a stable boundary layer develops at the ground (usually in late afternoon or early…
resonanceThe state of a system in which an abnormally large vibration is produced in response to an external stimulus, occurring when the frequency of the stimulus…
RespirationThe process whereby living organisms convert organic matter to CO2, releasing energy and consuming O2.
RidgeA line or wall of broken ice forced up by pressure. May be fresh or weathered.
RimeRime A white or milky and opaque granular deposit of ice formed by the rapid freezing of super-cooled water drops as they impinge upon an exposed object.
Rossby WavesA series of troughs and ridges on quasi-horizontal surfaces in the major belt of upper tropospheric westerlies.