Airmass RGB image showing a cold front stretching from the Baltic Sea through Denmark, across England and Wales and then into the Atlantic towards the Azores.
13 July 2022
03 December 2013
Over southern Europe the green to light blue colour indicates warm moist air. The paler green/orange colour to the west of France is a large area of low, layer cloud typical of this airstream.
To the north the purple to deep blue colour indicates the cold air on the northern side of the front. From Norway to Iceland there is a speckled cloud pattern. The whitish cells are shower clouds typical of cold air.
The temperature at 850hPa (about 1500m/5000ft) shows how the temperature changes rapidly across the front. As the front moved south over Edinburgh there was a marked change in the wind speed and direction and the temperature.
Before the passage of the front the wind was light south westerly as the front passed the wind veered round to a northerly direction. The temperature in the warm air was 10°C, after the front passed the temperature dropped to 4°C. A further indication of the change into cold air was the dew point temperature which fell from 8°C to just 1°C.