TERMIUM Plus®

The Government of Canada’s terminology and linguistic data bank.

POLAR LOW [2 records]

Record 1 2014-03-21

English

Subject field(s)
  • Atmospheric, Climatic and Meteorological Phenomena
DEF

The planetary-scale cyclonic circulation, centered generally in the polar regions, extending from the middle troposphere to the stratosphere.

OBS

The westerly airflow is largely a manifestation of the thermal wind above the polar frontal zone of middle and subpolar latitudes. The vortex is strongest in winter when the pole-to-equator temperature gradient is strongest. In the Northern Hemisphere, the vortex has two centers in the mean, one near Baffin Island and the other over northeast Siberia.

Key term(s)
  • circum-polar whirl
  • circum-polar vortex

French

Domaine(s)
  • Phénomènes météorologiques, climatiques et atmosphériques
DEF

Tourbillon créé en haute troposphère, au-dessus de chacun des pôles géographiques, par la circulation cyclonique des vents d'ouest.

CONT

Le phénomène du trou d'ozone est renforcé par l'existence de ce que l'on nomme le vortex polaire, un modèle de circulation particulier à la stratosphère au-dessus du pôle sud au cours de l'hiver austral et qui isole cette région de son environnement [...]

OBS

Le tourbillon circumpolaire isole la couche d'ozone polaire des masses d'air environnantes, plus riches en ozone.

OBS

Dans les textes techniques récents, probablement sous l'influence de l'anglais, c'est le terme «vortex polaire» qu'on emploie généralement.

Key term(s)
  • vortex circumpolaire

Spanish

Campo(s) temático(s)
  • Fenómenos meteorológicos, climáticos y atmosféricos
DEF

Zona semi aislada de circulación ciclónica constituida cada invierno en la estratosfera polar.

CONT

El vórtice polar austral es más fuerte que el septentrional. El vórtice aumenta el agotamiento del ozono al retener aire muy frío que contiene aerosoles y en el cual pueden tener lugar las reacciones de destrucción del ozono.

CONT

Al fenómeno que azota EE.UU. [Estados Unidos] se lo denomina “vórtice polar”. Es un sistema de baja presión profunda que se extiende a los niveles superiores de la atmósfera y hace descender masas heladas de aire que, por lo general, circulan alrededor del Círculo Polar Ártico.

Save record 1

Record 2 1992-12-31

English

Subject field(s)
  • Atmospheric, Climatic and Meteorological Phenomena
DEF

Small, shallow depression which forms mainly in winter over some high-latitude seas within a polar or arctic air mass.

CONT

When arctic-origin air in winter flows southward (northward in the southern hemisphere) across (relatively) warmer seas, strong surface heating acts both to enhance the degree of instability, and trigger vigorous moist convective towers. This is sufficient alone to give rise to heavy, wintry showers/cumulonimbus clusters etc., but often marked troughing, or even a closed circulation in the isobaric flow is found; the resultant low-level convergence/positive vorticity enhancement, plus the localised concentration of the latent heat energy released, enhances development within the system, and an intense (but synoptically small) area of rain, hail, sleet or snow & squally winds can result - a polar low (or polar depression or polar meso-cyclone in some texts).

CONT

What is a polar low? Part of a diverse group of mesoscale weather systems (polar meso-cyclones). ... [There is] three types of polar meso-cyclones: -jet streak type, -arctic front type, -cold low type.

OBS

Polar mesocyclones: a term now used to encompass the whole 'family' of disturbances resulting from arctic air flowing equatorward over progressively warmer seas; the term 'polar low' is now often used only for 'extreme' systems where gale or near gale-force winds are observed.

OBS

Its motion is approximately the same as the air stream in which it is embedded.

Key term(s)
  • polar meso cyclone

French

Domaine(s)
  • Phénomènes météorologiques, climatiques et atmosphériques
DEF

Petite dépression peu profonde qui se forme principalement en hiver dans une masse d'air polaire ou arctique située sur certaines mers des hautes latitudes.

OBS

Son mouvement est approximativement le même que celui du courant atmosphérique dans lequel elle se situe.

Spanish

Campo(s) temático(s)
  • Fenómenos meteorológicos, climáticos y atmosféricos
DEF

Depresión pequeña y poco profunda que se forma dentro de una masa de aire polar o ártico, especialmente en invierno, sobre los mares polares.

OBS

Se mueve siguiendo, aproximadamente, la dirección de la corriente de aire en que está inserta.

Save record 2

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