Test: Difference between revisions
From Glossary of Meteorology
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|Meaning=An accumulation of [[floating ice]] fragments less than 2 m across, formed by breakage of other [[ice]] forms. | |Meaning=An accumulation of [[floating ice]] fragments less than 2 m across, formed by breakage of other [[ice]] forms. | ||
|Explanation=Given the drop-size distribution of a sample of [[rain]], the radar reflectivity factor may be computed by summing the sixth-powers of the diameters of all the drops contained in a unit volume of space. Or, regarding the drop-size distribution ''N''(''D'') as a continuous function of [[drop]] size, the [[reflectivity factor|reflectivity factor]] ''Z'' may be written as <div class="display-formula"><blockquote>[[File:ams2001glos-Re9.gif|link=|center|ams2001glos-Re9]]</blockquote></div> For ice-phase precipitation, ''N''(''D'') is the distribution of melted diameters. Conventional units of ''Z'' are mm<sup>6</sup> m<sup>-3</sup> and it is sometimes measured on a [[logarithmic scale]] in units of [[Dbz|dB''Z'']]. The [[equivalent reflectivity factor]] ''Z''<sub>''e''</sub> may be estimated from measurements of the radar reflectivity η of precipitation and is defined by <div class="display-formula"><blockquote>[[File:ams2001glos-Re10.gif|link=|center|ams2001glos-Re10]]</blockquote></div> where λ is the radar [[wavelength]] and 0.93 is the [[dielectric factor]] for water. Either the reflectivity factor or the equivalent reflectivity factor is frequently used to estimate [[rainfall rate]] using relationships of the form ''Z'' = ''aR''<sup>''b''</sup>'','' where ''a'' and ''b'' are empirical constants and ''R'' is the rainfall rate. For ''R'' in millimeters per hour and ''Z'' or ''Z''<sub>''e''</sub> in mm<sup>6</sup> m<sup>-3</sup>, values of ''a'' range from 200 to 600 and those of ''b'' range from 1.5 to 2. The particular combination of ''a'' = 200 and ''b'' = 1.6 defines the [[Marshall-palmer relation|Marshall–Palmer relation]]. <br/> | |Explanation=Given the drop-size distribution of a '''sample''' of [[rain]], the radar reflectivity factor may be computed by summing the sixth-powers of the diameters of all the drops contained in a unit volume of space. Or, regarding the ''drop''-size distribution ''N''(''D'') as a continuous function of [[drop]] size, the [[reflectivity factor|reflectivity factor]] ''Z'' may be written as <div class="display-formula"><blockquote>[[File:ams2001glos-Re9.gif|link=|center|ams2001glos-Re9]]</blockquote></div> For ice-phase precipitation, ''N''(''D'') is the distribution of melted diameters. Conventional units of ''Z'' are mm<sup>6</sup> m<sup>-3</sup> and it is sometimes measured on a [[logarithmic scale]] in units of [[Dbz|dB''Z'']]. The [[equivalent reflectivity factor]] ''Z''<sub>''e''</sub> may be estimated from measurements of the radar reflectivity η of precipitation and is defined by <div class="display-formula"><blockquote>[[File:ams2001glos-Re10.gif|link=|center|ams2001glos-Re10]]</blockquote></div> where λ is the radar [[wavelength]] and 0.93 is the [[dielectric factor]] for water. Either the reflectivity factor or the equivalent reflectivity factor is frequently used to estimate [[rainfall rate]] using relationships of the form ''Z'' = ''aR''<sup>''b''</sup>'','' where ''a'' and ''b'' are empirical constants and ''R'' is the rainfall rate. For ''R'' in millimeters per hour and ''Z'' or ''Z''<sub>''e''</sub> in mm<sup>6</sup> m<sup>-3</sup>, values of ''a'' range from 200 to 600 and those of ''b'' range from 1.5 to 2. The particular combination of ''a'' = 200 and ''b'' = 1.6 defines the [[Marshall-palmer relation|Marshall–Palmer relation]]. <br /> | ||
|Same as=test, brash | |Same as=test, brash | ||
}}{{Definition | }}{{Definition | ||
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}} | }} | ||
|Link=brash | |Link=brash | ||
|See also=average velocity, dark lightning | |See also=average velocity, dark lightning, radar equation | ||
}} | }} | ||
Latest revision as of 12:27, 27 October 2023
1. An accumulation of floating ice fragments less than 2 m across, formed by breakage of other ice forms.
Given the drop-size distribution of a sample of rain, the radar reflectivity factor may be computed by summing the sixth-powers of the diameters of all the drops contained in a unit volume of space. Or, regarding the drop-size distribution N(D) as a continuous function of drop size, the reflectivity factor Z may be written as For ice-phase precipitation, N(D) is the distribution of melted diameters. Conventional units of Z are mm6 m-3 and it is sometimes measured on a logarithmic scale in units of dBZ. The equivalent reflectivity factor Ze may be estimated from measurements of the radar reflectivity η of precipitation and is defined by where λ is the radar wavelength and 0.93 is the dielectric factor for water. Either the reflectivity factor or the equivalent reflectivity factor is frequently used to estimate rainfall rate using relationships of the form Z = aRb, where a and b are empirical constants and R is the rainfall rate. For R in millimeters per hour and Z or Ze in mm6 m-3, values of a range from 200 to 600 and those of b range from 1.5 to 2. The particular combination of a = 200 and b = 1.6 defines the Marshall–Palmer relation.
2. [ abbr. TST ] (Rare.) In England, a colloquial term for a sudden gust of wind or the sudden onset of a storm.
3. Same as: brash
Read more: brash
See also: average velocity, dark lightning, radar equation
