Re: KNMI spreekt over een lijlaag, niet over een polar low

Tja... misschien ook wat minder aandacht voor omdat het niet ons land betreft?En dat ook nog in het weekend net na nieuwjaar. Ik snap het wel.

Maar... ook de term polar low is... overkoepelend voor enkele types...

Paar jaar geleden ontstonden er polar lows met parameters die niet voldoende mochten zijn. oander ander wales en Cornwall dacht ik... 

De oorzaak was orografie! En de formatie van een leelow. Dat dus de trigger was en zo een polar low wel mogelijk was!

Mooie uitleg is te vinden in dit artikel van ecmwf:

https://www.ecmwf.int/sites/default/files/elibrary/2007/12857-polar-lows-and-other-high-latitude-weather-systems.pdf

quote:

We now know that there are many different types of polar low, plus various hybrid types of system, but in
Rasmussen and Turner (2003) they identified seven categories of low that are found in the Arctic:
1. Reverse shear-systems. These are a baroclinic type of development that often forms between Iceland
and Spitsbergen when the surface winds are from the north or north-east and the mid-tropospheric
winds from the southwest.
2. Trough systems. Developing in trailing troughs in the cold Arctic air masses to the west of major
synoptic-scale lows.
3. Lows forming on boundary layer fronts separating Arctic air masses of different characteristics. This
type of polar low is often found around Svalbard or near the edge of the sea ice.
4. Cold lows (including merry-go-round systems). Such systems can be observed as spiral cloud patterns
in the centre of old, barotropic synoptic-scale lows. The term merry-go-round system refers to a
number of polar lows rotating together within an old synoptic-scale low. A cold low system is shown
in Fig. 4.
5. Comma clouds. Such systems were first identified in the Pacific where comma-shaped cloud bands
were observed close to the main polar front. Interactions between comma clouds and the polar front
can result in ‘instant occlusion’ developments where the polar low and front merge to produce a
system with the appearance of a frontal cyclone. Here the polar low provides the ‘occlusion’ and the
polar front the warm and cold fronts.
6. Baroclinic wave-forward shear. These are the polar lows that have the appearance of small-scale
frontal cyclones, such as illustrated in Fig. 2. They develop on minor baroclinic zones, such as those
found near the edge of the sea ice.
7. Orographic polar lows. These are lee lows that develop into active mesoscale vortices in locations such
as south of Iceland (during a northerly outbreak) and to the east of Greenland