Operation Cumulus was a project of the UK government in the 1950s which was investigating weather manipulation, in particular through cloud seeding experiments. Known jokingly within the project as Operation Witch Doctor, the project was operational between 1949 and 1952.
- "bogging down enemy movement";
- "incrementing the water flow in rivers and streams to hinder or stop enemy crossings";
- clearing fog from airfields.
The Lynmouth disaster
On 16 August 1952 a severe flood occurred in the town of Lynmouth in north Devon. 9 inches (229 millimetres) of rain fell within twenty-four hours "Ninety million tonnes of water swept down the narrow valley into Lynmouth" and the East Lyn River rose rapidly and burst its banks. Thirty-five people died and many buildings and bridges were seriously damaged. According to BBC, "North Devon experienced 250 times the normal August rainfall in 1952."
- Vidal, John and Helen Weinstein, RAF rainmakers 'caused 1952 flood', The Guardian, 2001-08-30, retrieved 2007-07-21.
- 1952: Flood devastates Devon village, BBC
- Rain-making link to killer floods, BBC, 2001-08-30, retrieved 2007-07-21
- Hilary Bradt; Janice Booth (11 May 2010). Slow Devon and Exmoor. Bradt Travel Guides. p. 249. ISBN 978-1-84162-322-1.
- The day they made it rain, Philip Eden, WeatherOnline