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As part of my learning to the meteorology exam for PPL I seen the following question -

"What is the usual direction of movement of a polar front low?"

the answer is - "Parallel to the warm-sector isobars"

the first problem here that I didn't found any information about what is a Polar front Low? is it the same as just Polar Low ? a polar air mass depression?

second problem, I didn't found any information about why the polar front low movement is parallel to the warm-sector isobars... can someone please refer any relevant information?

I really tried to find the answer myself...

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A polar front low is a low pressure system that's associated with the polar front. Polar front is the prevailing front (the red line in the picture) between the polar air cell and the Ferrell cell.

enter image description here

Sometimes a local disturbance in the polar front forms. How and why exactly these disturbances begin to form, is way above my education, but I don't think anyone else knows either (I read an article about that a few years ago, and basicly it said "nobody knows" spanned over 8 pages). There are several contributing factors, including the North Atlantic Oscillation, air pressures, winds etc.
Simplified though, "a dent" in the polar front forms and begins to rotate and move along the polar front. This local low pressure system is called the polar front low.

A cold and warm front form adjacent to the low pressure center. Both fronts have their own movement direction and speed, and they rotate around the low pressure center.

Source: http://www.eumetrain.org/satmanu/polar_front_theory/index.html
Source: http://www.eumetrain.org/satmanu/polar_front_theory/index.html

The whole system moves in the direction of the isobars in the warm sector, and with the speed of about 80% of the geostrophic scale measured between the first and second isobars in the warm sector (the red area in the third picture).

enter image description here

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  • $\begingroup$ Thanks for the perfect answer!!! $\endgroup$ Jan 22, 2022 at 16:06
  • $\begingroup$ Meteorology is a complicated subject. I'm glad if I was able to shed some light on the matter. $\endgroup$
    – Sami
    Jan 22, 2022 at 17:44

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