article_snippet.sent: Polar plunge: This graphic from Netweather shows the temperature at 850hPa (5,000ft) and the pressure at sea level as of midnight today .
article_snippet.sent: But the dramatic change is being brought in by a ‘polar plume’ - a cold mass of air moving down from polar regions.
article_snippet.sent: Surface pressure: A cold front (in blue triangles) can be seen moving away from Britain at midnight today after arriving over the weekend .
article_snippet.sent: How it works: This Met Office moving graphic shows how the arrival of an Arctic Maritime air mass is affecting temperatures in the UK .