- On August 15, 1952, one of the worst flash floods ever
to have occurred in Britain swept through the Devon village of Lynmouth.
Thirty five people died as a torrent of 90m tons of water and thousands
of tons of rock poured off saturated Exmoor and into the village destroying
homes, bridges, shops and hotels.
- The disaster was officially termed "the hand of
God" but new evidence from previously classified government files
suggests that a team of international scientists working with the RAF was
experimenting with artificial rainmaking in southern Britain in the same
week and could possibly be implicated.
- Squadron Leader Len Otley, who was working on what was
known as Operation Cumulus, has told the BBC that they jokingly referred
to the rainmaking exercise as Operation Witch Doctor.
- His navigator, Group Captain John Hart, remembers the
success of these early experiments: "We flew straight through the
top of the cloud, poured dry ice down into the cloud. We flew down to see
if any rain came out of the cloud. And it did about 30 minutes later, and
we all cheered."
- The meteorological office has in the past denied there
were any rainmaking experiments conducted before 1955, but a BBC Radio
4 history investigation, to be broadcast tonight, has unearthed documents
recently released at the public record office showing that they were going
on from 1949 to 1955. RAF logbooks and personnel corroborate the evidence.
- Until now, the Ministry of Defence has categorically
denied knowledge of any cloud-seeding experiments taking place in the UK
during early August 1952. But documents suggest that Operation Cumulus
was going on between August 4 and August 15 1952. The scientists were based
at Cranfield school of aeronautics and worked in collaboration with the
RAF and the MoD's meteorological research flight based at Farnborough.
The chemicals were provided by ICI in Billingham.
- Met office reports from these dates describe flights
undertaken to collect data on cumulus cloud temperature, water content,
icing rate, vertical motions and turbulence, and water droplet and ice
crystal formation. There is no mention of cloud seeding.
- But a 50-year-old radio broadcast unearthed by Radio
4 describes an aeronautical engineer and glider pilot, Alan Yates, working
with Operation Cumulus at the time and flying over Bedfordshire, spraying
quantities of salt. He was elated when the scientists told him this had
led to a heavy downpour 50 miles away over Staines, in Middlesex.
- "I was told that the rain had been the heaviest
for several years - and all out of a sky which looked summery ... there
was no disguising the fact that the seedsman had said he'd make it rain,
and he did. Toasts were drunk to meteorology and it was not until the BBC
news bulletin [about Lynmouth] was read later on, that a stony silence
fell on the company," said Mr Yates at the time.
- Operation Cumulus was put on hold indefinitely after
- Declassified minutes from an air ministry meeting, held
in the war office on November 3, 1953, show why the military were interested
in increasing rain and snow by artificial means. The list of possible uses
included "bogging down enemy movement", "incrementing the
water flow in rivers and streams to hinder or stop enemy crossings",
and clearing fog from airfields.
- The documents also talk of rainmaking having a potential
"to explode an atomic weapon in a seeded storm system or cloud. This
would produce a far wider area of radioactive contamination than in a normal
- UK weather modification experiments at the time presaged
current practice in the US. The idea was to target "super cool"
clouds, and to increase the volume of freezing water vapour particles.
Most methods involved firing particles of salt, dry ice, or silver iodide,
into clouds, either from an aeroplane or from burners on the ground. The
clouds would then precipitate, pulled down below freezing point by the
extra weight of dense particles, thus making it rain sooner and heavier
than it might have done. Significantly, it was claimed that silver iodide
could cause a downpour up to 300 miles away.
- Many countries now use the technology, which has considerably
improved during the past 50 years.
- But controversy still surrounds the efficacy of these
early cloud-seeding experiments. In 1955 questions were asked in the Commons
about the possibilites of liability and compensation claims. Documents
seen by the BBC suggest that both the air ministry and the Treasury became
very anxious and were aware that rainmaking could cause damage, not just
to military targets and personnel, but also to civilians.
- The British Geological Survey has recently examined soil
sediments in the district of Lynmouth to see if any silver or iodide residues
remain. The testing has been limited due to restrictions in place because
of foot and mouth disease, and it is inconclusive. However, silver residue
has been discovered in the catchment waters of the river Lyn. The BGS will
investigate further over the next 18 months.
- Survivors of the Lynmouth flood called for - but never
got - a full investigation into the causes of the disaster. Rumours persist
to this day of planes circling before the inundation.