TERMIUM Plus^®

Fiche 1,  Justifications,  Anglais

Record number: 1, Textual support number: 1 CONT

An issue of considerable interest is the so-called multicellular thunderstorm system, as opposed to supercells, which are often presumed to be unicellular. A form of multicellular convection that has already been simulated extensively is the squall line. The typical method for simulating this form of deep line-oriented convection has been to release a number of laterally-aligned IB’s. After the initial storms develop, their outflows merge, producing a line of convection resembling a squall line. Squall lines are not the only type of multicellular convection observed, however. In isolated multicell storms, a succession of updrafts is typical.  1, fiche 1, Anglais, - multicellular%20thunderstorm%20system

Record number: 1, Textual support number: 1 OBS

Thunderstorms are often classified into a spectrum based on their cell structure : single cells, multicellular storms, and supercells. The type of storm depends on the instability and relative wind conditions at different layers of the atmosphere(shear). The "single-cell"(unicell) thunderstorm is [a] three-stage situation... usually lasting about 30 minutes from the start of significant precipitation. A severe unicell storm is often referred to as a pulse thunderstorm.... In a multicell thunderstorm, several thunderstorm cells merge into a larger system. The cloud becomes divided into updraft and downdraft regions separated by a gust front. The gust front may extend for several miles ahead of the storm, bringing with it increases in wind speed and atmospheric pressure, decreases in temperature, and shifts in wind direction. The storm itself will have different portions sequentually going through the various thunderstorm stages. In many cases the immature cells develop along a line known as a "flanking line, "resulting in what is known as a line multicell.  6, fiche 1, Anglais, - multicellular%20thunderstorm%20system

Record number: 1, Textual support number: 2 OBS

storm system: Often refers to "thunderstorm system" (in French: "système orageux"), which is a frequent type of storm system but not the only one; an elliptic form which can be used when there is no risk of ambiguity.  3, fiche 1, Anglais, - multicellular%20thunderstorm%20system

Fiche 1,  Justifications,  Français

Fiche 1,  Justifications,  Espagnol

Fiche 2,  Justifications,  Anglais

Record number: 2, Textual support number: 1 CONT

The gustnado has been accepted as a "type of tornado" but is not associated with the typical tornado characteristics. It is a brief, intense vortex that forms on the leading edge of severe gust fronts. Scud and debris or dirt may be seen but a condensation funnel is usually absent. They will last from a few seconds to a minute and are strong enough to cause minor damage. They are distinguished from a true tornado by their location under an advancing dark cloud bank ahead of the rain core. Although the air is rotating, the situation would group this event more appropriately with straight-line winds.  2, fiche 2, Anglais, - straight%2Dline%20winds

Record number: 2, Textual support number: 2 CONT

The leading edge of a gust front(or downburst) often creates an area of convergence which can lead to future thunderstorm growth; close monitoring of visible gust fronts becomes very important in forecsting areas of future storm development. Gust fronts from a line of cells, such as a squall line, can form an elongated area of divergence and convergence. These elongated areas or squall line gust fronts are important components to the squall line structure, and often times a producer of severe weather due to straight-line winds.  3, fiche 2, Anglais, - straight%2Dline%20winds

Fiche 2,  Justifications,  Français

Record number: 2, Textual support number: 1 CONT

«gustnado» : On la considère comme un «type de tornade» mais elle n'a pas les caractéristiques habituelles de la tornade. C'est un tourbillon intense et de courte durée qui se forme sur la bordure antérieure d'un fort front de rafales. On peut voir des nuages en lambeaux et des débris ou de la poussière, mais rarement d'entonnoir de condensation. La «gustnado» dure de quelques secondes à une minute et peut causer des dégâts mineurs. Elle se distingue de la vraie tornade par sa place au-dessous d'un banc de nuages sombres qui approche, à l'avant du noyau de pluie. Même si l'air est en rotation, la situation porte à classer ce phénomène avec les vents rectilignes.  1, fiche 2, Français, - vents%20rectilignes

Fiche 2,  Justifications,  Espagnol

Fiche 3,  Justifications,  Anglais

Record number: 3, Textual support number: 1 CONT

The laser(or lidar) velocimeter [lidar=light radar] operates in a fashion entirely analogous to that of the airborne Doppler weather radars likely soon to be available for detecting turbulence in storm cells. As with radars, the device detects air movements by observing the motion of particles suspended in the air and carried with it. The only significant difference is that a beam of coherent infrared radiation is used to scan ahead of the aircraft, instead of a beam(or series of pulses) of radio energy in the considerably longer-wavelength microwave band. The frequency of the back-scattered echoes or reflections undergoes Doppler shift detection by standard heterodyning techniques, which involve comparing the frequency of the reflected illumination with that of the original laser beam. Any reflecting object or material which has motion relative to the transmitter/receiver will cause a detectable shift in frequency, which can be isolated from the transmitter's own proper motion(over the ground) and thus yield a precise indication of the speed at which the air is moving several hundred metres in front of the aircraft. From this data, it is easy to compute what the air speed of the aircraft will be when it reaches that particular patch of air in a few seconds’ time [and hence detect possible turbulence ahead].  2, fiche 3, Anglais, - laser%20velocimeter

Fiche 3,  Justifications,  Français

Record number: 3, Textual support number: 1 CONT

Le principe de fonctionnement du vélocimètre à laser (ou lidar) est exactement le même que celui des radars météorologiques Doppler de bord, qui doivent être mis en service prochainement pour la détection des turbulences dans les systèmes d'orages.  1, fiche 3, Français, - v%C3%A9locim%C3%A8tre%20%C3%A0%20laser

Fiche 3,  Justifications,  Espagnol