Coined word for radio detection and ranging. An electronic instrument, consisting of a transmitter, receiver, antenna, display, and associated equipment for control and signal processing, which is used for the detection and ranging of distant objects (such as tropical cyclones) that scatter or reflect radio energy. The colors in a radar output correspond to the different values of energy that are reflected back toward the radar. Called echoes, the reflected intensities are measured in dBZ (decibels of z). As the strength of the signal returned to the radar increases (i.e. there is more precipitation to cause a reflection in energy) the dBZ values increases. Source: Glossary of Meteorology. (c)American Meteorological Society. Reprinted with permission.

Speed component of the wind at a point in a direction along a radius vector from the center of a circulating wind system. Source: (c) 1999, American Meteorological Society. Used with permission.

Energy that comes from a source and is transmitted in the form of rays, waves, or particles. Light and heat are types of radiation.

An instrument attached to a weather balloon that transmits pressure, humidity, temperature and winds as it ascends to the upper atmosphere. Source: NOAA-NWS ERH

The distance from the center of a tropical cyclone to the location of the maximum winds of a cyclone. In well-developed hurricanes, the radius of maximum winds is generally found at the inner edge of the eyewall. Source NOAA-NHC.

A decrease in the minimum sea-level pressure of a tropical cyclone of 1.75 mb/hr or 42 mb for 24 hours. Source NOAA-NHC.

A balloon that is tracked by radar to measure wind speeds and wind directions in the atmosphere. Source: NOAA-NWS ERH

A change in direction of a wave, such as a light or sound wave, away from a boundary the wave encounters.

Radar term referring to the ability of a radar target to return energy; used to estimate precipitation intensity and rainfall rates. Source: NOAA-NWS ERH

A dimensionless ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature. As such, relative humidity by itself does not directly indicate the actual amount of atmospheric moisture present. See dew point. Source: NOAA-NWS SRH

A post-tropical cyclone that no longer possesses the convective organization required of a tropical cyclone and has maximum sustained winds of less than 62 km/h (39 mph). The term is most commonly applied to the nearly deep-convection-free swirls of stratocumulus in the eastern North Pacific. Source NOAA-NHC.

The scale in space or time of a model. High resolution means the spatial scale between model points is smaller.

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