In the hours before floods swept through Cumbria, the heaviest rain ever recorded in Britain fell on a hamlet in the county. Philip Eden unpicks the unique combination of factors which made this happen.
1. A 'conveyor' of warm, very moist sub-tropical air was carried towards Britain from south of the Azores
2. When this mass of warm air - which holds more moisture than cold air - was blown by high winds over Cumbria's mountains it cooled, allowing the moisture to condense as heavy rain
3. What made matters worse was that the weather system, which extended south-west from Britain for thousands of miles into the Atlantic, got stuck over the hills of Cumbria and southern Scotland
4. The falling heavy rain entered the region's rivers, which were forced to carry exceptionally high water loads
5. This led to significant flooding, especially at their confluences, such as in Cockermouth
