0:00:02 > 0:00:03It's variable.
0:00:03 > 0:00:07It's hard to predict, it has a massive impact
0:00:07 > 0:00:09every hour of every day.
0:00:09 > 0:00:11It is, of course, the weather.
0:00:14 > 0:00:16I'm Alok Jha
0:00:16 > 0:00:18and I'm a science journalist.
0:00:20 > 0:00:23I want to investigate how, through history,
0:00:23 > 0:00:26people have tried to predict what the weather will do.
0:00:28 > 0:00:32That's what this series is about, the story of the extraordinary
0:00:32 > 0:00:36characters who took on one of the hardest problems in science.
0:00:36 > 0:00:37How to forecast the weather.
0:00:39 > 0:00:41In this episode:
0:00:41 > 0:00:43The ambulance driver who dreamed up the first
0:00:43 > 0:00:47weather computer in the trenches of World War I.
0:00:48 > 0:00:52The scientist who tried to predict weather disasters
0:00:52 > 0:00:54and helped unlock global climate systems.
0:00:56 > 0:00:58And the weathermen who risked their lives to help
0:00:58 > 0:01:01win the Second World War.
0:01:01 > 0:01:04I thought sometimes that I wonder if we can get back all right.
0:01:05 > 0:01:08This is a story with a dark side.
0:01:08 > 0:01:11All of the accomplishments that scientists made
0:01:11 > 0:01:15in understanding the weather came out of catastrophe...
0:01:15 > 0:01:17natural disaster...
0:01:17 > 0:01:19and war.
0:01:19 > 0:01:24This was half a century which tested meteorologists to their limits.
0:01:39 > 0:01:42These are cirrus clouds.
0:01:42 > 0:01:45Probably the most beautiful clouds in the sky.
0:01:46 > 0:01:49They are pale and wispy.
0:01:49 > 0:01:53Some people have called them mare's tails or compared them
0:01:53 > 0:01:55to long strands of hair.
0:01:58 > 0:02:01Cirrus clouds have fascinated skywatchers for centuries.
0:02:03 > 0:02:05They are said to signal stormy weather.
0:02:07 > 0:02:09There was actually a maritime saying,
0:02:09 > 0:02:12"If you see mare's tails, carry low sails."
0:02:12 > 0:02:14Because bad weather's on the way.
0:02:18 > 0:02:22But in a village in Leicestershire in the 19th century,
0:02:22 > 0:02:25the local rector decided to take a scientific approach
0:02:25 > 0:02:27to studying cirrus clouds.
0:02:30 > 0:02:32His name was William Clement Ley.
0:02:34 > 0:02:38And in Ashby Parva, he had a reputation as a weather prophet.
0:02:40 > 0:02:41During harvest time,
0:02:41 > 0:02:45Ley would post his weather forecasts on these rectory gates
0:02:45 > 0:02:48and it's said that farmers would come from miles around
0:02:48 > 0:02:51to read the forecasts and only then would they decide
0:02:51 > 0:02:54when to cut their corn or their hay.
0:02:57 > 0:03:01Ley knew that the livelihood of the farmers depended on the weather.
0:03:05 > 0:03:09A bad harvest could bring hardship to entire communities.
0:03:11 > 0:03:14So Ley made it his life's work to try
0:03:14 > 0:03:17and find a way to predict storms and bad weather.
0:03:20 > 0:03:22He used a simple instrument.
0:03:22 > 0:03:25It is thought he designed and built his own.
0:03:25 > 0:03:28This is a nephoscope and it's probably less complicated than
0:03:28 > 0:03:32the one that Ley would have built, but the principle is the same.
0:03:32 > 0:03:37All around, there are 360 degrees of markings.
0:03:37 > 0:03:42The zero points directly north and once you've set it up properly,
0:03:42 > 0:03:44you just watch the clouds in the mirror.
0:03:47 > 0:03:50Ley spent years plotting the clouds.
0:03:53 > 0:03:55Cirrus clouds fascinated him.
0:03:55 > 0:04:00They're the highest in the sky, at 18,000 feet and above.
0:04:03 > 0:04:07For him, clouds were not just things of beauty and grace.
0:04:10 > 0:04:11He realised they could provide clues
0:04:11 > 0:04:15which could help to predict the weather.
0:04:17 > 0:04:20This is a diagram made by Ley in 1877
0:04:20 > 0:04:22and it shows a model of a depression,
0:04:22 > 0:04:24a low-pressure weather system,
0:04:24 > 0:04:28of the kind that blows in from the west to Britain all the time.
0:04:28 > 0:04:31It's this that brings unsettled weather to the UK,
0:04:31 > 0:04:33rain, clouds, even gales.
0:04:35 > 0:04:38Low-pressure systems often dominate the weather
0:04:38 > 0:04:39in mid-to-high latitudes
0:04:39 > 0:04:42around northern America and northern Europe.
0:04:42 > 0:04:46Understanding how they worked was the Holy Grail of meteorology.
0:04:50 > 0:04:53Ley had cracked something extraordinary.
0:04:53 > 0:04:57The structure of a low-pressure centre in three dimensions.
0:05:00 > 0:05:03On this diagram, Ley marked the direction of the winds.
0:05:03 > 0:05:06You can see at the bottom where these solid lines are,
0:05:06 > 0:05:08the winds are rotating counterclockwise
0:05:08 > 0:05:10around this central area,
0:05:10 > 0:05:12and the whole pressure system is moving that way.
0:05:12 > 0:05:14But as the winds move around here,
0:05:14 > 0:05:21they move up and the winds at the top are diverging outwards.
0:05:24 > 0:05:28Modern satellite images show that Ley was remarkably accurate
0:05:28 > 0:05:33in working out what was happening thousands of feet up in the air.
0:05:33 > 0:05:37Because of his careful observations of cirrus cloud,
0:05:37 > 0:05:42Ley identified that on occasions, the upper flow was moving
0:05:42 > 0:05:48at tremendous velocities and he measured speeds in excess of 150mph.
0:05:50 > 0:05:53That would later be termed as part of the jet stream.
0:05:55 > 0:05:59The jet stream is now recognised as a crucial part of how weather works.
0:06:00 > 0:06:03But at the time, it was completely unknown.
0:06:08 > 0:06:12Ley also gathered observations showing that cirrus clouds often
0:06:12 > 0:06:14appear before an approaching low.
0:06:18 > 0:06:22So he called for an international forecasting system to be set up.
0:06:25 > 0:06:29Observers along the coasts of Europe could spot cirrus clouds
0:06:29 > 0:06:33approaching and telegraph the data to a central forecasting office.
0:06:35 > 0:06:38Improved storm warnings could have saved lives
0:06:38 > 0:06:39in the 19th century.
0:06:41 > 0:06:44In the age of sail, shipwrecks were all too common
0:06:44 > 0:06:48and rural communities were blighted by extreme weather events.
0:06:51 > 0:06:53Towards the end of his life,
0:06:53 > 0:06:56Ley wrote a book pleading with the scientific world to take note.
0:07:30 > 0:07:33But the scientific establishment didn't listen.
0:07:34 > 0:07:38And his idea of using cirrus clouds was stillborn.
0:07:39 > 0:07:44William Clement Ley is buried here in this quiet grave in Ashby Parva.
0:07:44 > 0:07:46He had a sad end.
0:07:46 > 0:07:48Towards the end of his life,
0:07:48 > 0:07:51he was admitted to a mental institution in London.
0:07:52 > 0:07:55In 1896, he was found dead.
0:07:55 > 0:08:00An inquest found he'd killed himself while "of unsound mind".
0:08:01 > 0:08:04It's said the local farmers gathered together
0:08:04 > 0:08:06one more time for his funeral.
0:08:08 > 0:08:12It's difficult to overestimate Ley's work.
0:08:13 > 0:08:17When he died, any idea of using upper flow
0:08:17 > 0:08:20essentially died with him.
0:08:20 > 0:08:25There was this huge gap of about 40 years that was
0:08:25 > 0:08:28literally lost in terms of meteorological advancement.
0:08:31 > 0:08:35But, as we'll see, Ley did leave a legacy.
0:08:35 > 0:08:39One which was to inform future scientists
0:08:39 > 0:08:42in their search for the secrets of the skies.
0:08:53 > 0:08:56At the beginning of the 20th century,
0:08:56 > 0:09:00the Met Office was based in Central London above a piano shop.
0:09:02 > 0:09:04It was underfunded
0:09:04 > 0:09:08and did very little original research into the upper atmosphere.
0:09:12 > 0:09:17It took the outbreak of war in 1914 for modern forecasting to be born.
0:09:21 > 0:09:23The First World War was a human disaster.
0:09:27 > 0:09:32When fighting broke out, the British Army saw no need for meteorology.
0:09:32 > 0:09:35They planned to fight wars the old way.
0:09:36 > 0:09:38But soon, that had to change.
0:09:38 > 0:09:43By 1915, there was a grisly stalemate on the Western Front.
0:09:43 > 0:09:46The British Army's high command realised they were facing
0:09:46 > 0:09:49a new type of scientific, highly technological warfare
0:09:49 > 0:09:53and it was something they were hopelessly unprepared for.
0:09:53 > 0:09:56This was a war using new technology.
0:09:56 > 0:09:59One of the most significant was airplanes.
0:09:59 > 0:10:03They were mostly used for observational purposes over
0:10:03 > 0:10:04the battlefield.
0:10:04 > 0:10:05They were fragile,
0:10:05 > 0:10:10lightweight machines at the mercy of strong winds.
0:10:10 > 0:10:13Commanders soon realised they needed scientific input.
0:10:17 > 0:10:21So, in spring 1915, the Royal Flying Corps sent a telegram
0:10:21 > 0:10:23to the Met Office asking for their help.
0:10:25 > 0:10:29An organisation called the Meteorological Field Service
0:10:29 > 0:10:32was set up, commonly known as Meteor.
0:10:34 > 0:10:38It set about gathering weather data along the front line.
0:10:38 > 0:10:41They started off by using thousands of these things,
0:10:41 > 0:10:44pilot balloons. And the method was very simple.
0:10:44 > 0:10:48They let them off and then two men with the odd light would track them
0:10:48 > 0:10:49as they rose through the air.
0:10:52 > 0:10:56This was a basic way of working out the speed and direction of the wind.
0:11:00 > 0:11:03But more sophisticated instruments were needed, because the war
0:11:03 > 0:11:07was getting more complicated, especially for artillery.
0:11:09 > 0:11:11Artillery was the most important weapon
0:11:11 > 0:11:13system in the whole of the First World War.
0:11:13 > 0:11:161914 to 1918 marked a revolution in warfare.
0:11:16 > 0:11:19It was the first time that artillery became the predominant
0:11:19 > 0:11:21killer on the battlefield.
0:11:21 > 0:11:23In the 19th century and the wars of Napoleon,
0:11:23 > 0:11:26artillery had accounted for between five and 10% of all casualties.
0:11:26 > 0:11:28By the time of the First World War,
0:11:28 > 0:11:32artillery accounted for around 80% of all battlefield casualties.
0:11:34 > 0:11:38By 1917, battle lines had got deeper and deeper.
0:11:40 > 0:11:45Trenches now stretched back five, seven, sometimes ten miles.
0:11:45 > 0:11:47EXPLOSIONS
0:11:47 > 0:11:50Firing at longer ranges than ever before, firing the blind,
0:11:50 > 0:11:52firing from map coordinates,
0:11:52 > 0:11:55and flinging their shells up to 14,000 feet into the air,
0:11:55 > 0:11:58it was essential that the gunners understood weather conditions,
0:11:58 > 0:12:00atmospherics and wind speed.
0:12:01 > 0:12:05This long-range form of warfare meant shells were hanging
0:12:05 > 0:12:07longer in the air.
0:12:07 > 0:12:10They were much more vulnerable to the temperature
0:12:10 > 0:12:11and density of the atmosphere.
0:12:13 > 0:12:17Meteor needed a new way of getting information from higher in the air.
0:12:23 > 0:12:25Of course, what they really needed
0:12:25 > 0:12:28was access to these beautiful things - biplanes.
0:12:28 > 0:12:32These were the technological marvels of their age.
0:12:33 > 0:12:37For most of the war, biplanes were used for military purposes,
0:12:37 > 0:12:40like spotting targets for the artillery.
0:12:40 > 0:12:44But there was someone doing pioneering research work
0:12:44 > 0:12:46while flying over the front line.
0:12:46 > 0:12:49He was an officer with the Royal Flying Corps.
0:12:51 > 0:12:55He was universally known by his initials - CKM Douglas.
0:12:59 > 0:13:02At first, Douglas fought as an artillery spotter in the war.
0:13:02 > 0:13:05It was an extremely dangerous and difficult job.
0:13:05 > 0:13:08You'd have to sit in a box in the nose of the plane,
0:13:08 > 0:13:10fully exposed to the elements.
0:13:12 > 0:13:15Douglas retrained as a pilot and was shot down three times...
0:13:17 > 0:13:22..once by a squadron of German aces headed by Hermann Goering himself.
0:13:23 > 0:13:26But incredibly, during all the fighting,
0:13:26 > 0:13:28Douglas was indulging his real passion.
0:13:31 > 0:13:33He was fascinated by the weather.
0:13:35 > 0:13:38And he had an inspiring figure to draw upon.
0:13:39 > 0:13:43Douglas read The Reverend Ley's writings from 40 years before.
0:13:45 > 0:13:47He admired his work on clouds
0:13:47 > 0:13:50and how you can use them to predict bad weather.
0:13:54 > 0:13:58Douglas used his time in the air to conduct his own private
0:13:58 > 0:14:02research, and now I'm going to try to the same thing.
0:14:04 > 0:14:05I'm going to take with me
0:14:05 > 0:14:08the instruments that Douglas would have had during the war years.
0:14:08 > 0:14:11So I have my altimeter fixed to the cockpit here,
0:14:11 > 0:14:13there's a thermometer fixed to the side there.
0:14:13 > 0:14:17What Douglas did was to measure the differences in temperature
0:14:17 > 0:14:20as he rose to different heights through the air, which is
0:14:20 > 0:14:21exactly what I'm going to do.
0:14:23 > 0:14:24Contact.
0:15:30 > 0:15:35Up here, Douglas got an astonishing view of different cloud structures.
0:15:35 > 0:15:37At 8,000 feet,
0:15:37 > 0:15:41he said he could see the tops of cumulonimbus 100 miles away.
0:15:43 > 0:15:46He was one of the first people in the world to realise
0:15:46 > 0:15:49how useful airplanes would be in meteorology.
0:16:25 > 0:16:28Lovely, thank you very much. It's beautiful.
0:16:28 > 0:16:30As we rose through the air, I did manage to write down
0:16:30 > 0:16:32the temperatures at different heights,
0:16:32 > 0:16:35and even in my very unscientific survey, you can see that
0:16:35 > 0:16:39the temperature, as you go up, does decrease fairly consistently.
0:16:39 > 0:16:42On the ground it was 12 degrees Celsius.
0:16:42 > 0:16:43By the time I got to 1,500 feet,
0:16:43 > 0:16:46it was eight degrees Celsius in the air.
0:16:46 > 0:16:49The reason Douglas was interested in how temperature changes with
0:16:49 > 0:16:51height is because it's such an important
0:16:51 > 0:16:54part of understanding how the weather changes.
0:16:54 > 0:16:56And that's very closely linked to a question
0:16:56 > 0:17:00we all ask ourselves around the British Isles - is it going to rain?
0:17:02 > 0:17:06Douglas was investigating the fundamental physics of weather.
0:17:06 > 0:17:09Warm air holds more water vapour than cold.
0:17:11 > 0:17:14As the air rises, the vapour condenses to form clouds.
0:17:16 > 0:17:20And if the cloud becomes too heavy, the water falls as rain.
0:17:20 > 0:17:22THUNDER RUMBLES
0:17:25 > 0:17:29My own reading showed that the temperature was dropping over
0:17:29 > 0:17:32three degrees per 1,000 feet, which is faster than average.
0:17:34 > 0:17:36It's probably because the air was quite dry.
0:17:38 > 0:17:40Temperature drops faster in drier air.
0:17:42 > 0:17:45Because there was less moisture, there were no clouds.
0:17:45 > 0:17:49So we had a beautiful day for the flight.
0:17:52 > 0:17:56After the war, Douglas became one of Britain's foremost meteorologists.
0:17:56 > 0:17:59He wrote ground-breaking papers and became one of the leading
0:17:59 > 0:18:02forecasters during the Second World War.
0:18:04 > 0:18:08As for Meteor, it finally got its own planes to take readings.
0:18:11 > 0:18:14This helped the artillery increase in accuracy
0:18:14 > 0:18:17and contributed to the Allied victory.
0:18:20 > 0:18:24But the question remained, how could you use all this information
0:18:24 > 0:18:26to accurately forecast the weather?
0:18:33 > 0:18:35The way ahead lay in physics.
0:18:37 > 0:18:40It was known at the time that all the variables of weather,
0:18:40 > 0:18:44wind speed, temperature, humidity
0:18:44 > 0:18:46are base-specific laws of physics.
0:18:50 > 0:18:55But what wasn't known was how to turn the physics into forecasts.
0:18:57 > 0:19:01Professor Ian Roulstone is an expert on the terrifyingly complex
0:19:01 > 0:19:03maths of weather.
0:19:03 > 0:19:07So, let's write down the equations that we use in weather forecasting.
0:19:07 > 0:19:10And we'll start what is eventually Newton's law of motion
0:19:10 > 0:19:12for the atmosphere.
0:19:12 > 0:19:14This tells us how wind speed
0:19:14 > 0:19:18and direction is affected by things like that Coriolis effect,
0:19:18 > 0:19:21which is due to earth's rotation.
0:19:21 > 0:19:23Then, of course, gravity also plays a role.
0:19:24 > 0:19:27Then we need to add the pressure gradient term,
0:19:27 > 0:19:31and finally we add a term which represents friction.
0:19:31 > 0:19:34And that's just for the wind.
0:19:34 > 0:19:38You need an equation for air density,
0:19:38 > 0:19:41one for pressure related to density and temperature.
0:19:42 > 0:19:45You need the first law of thermodynamics.
0:19:47 > 0:19:49And you need an equation for water vapour,
0:19:49 > 0:19:51condensation and evaporation.
0:19:56 > 0:19:58So here we have it, on one board,
0:19:58 > 0:20:02all the equations that encapsulate the physics of the atmosphere.
0:20:04 > 0:20:06But that's just a theory.
0:20:06 > 0:20:10In the real world, all the variables, in all the equations,
0:20:10 > 0:20:14act on each other all the time.
0:20:14 > 0:20:18So, wind speed and direction responds to changes in pressure.
0:20:18 > 0:20:21The changing wind blows clouds around,
0:20:21 > 0:20:24so that alters the temperature distribution.
0:20:24 > 0:20:28It also alters where moisture is in the atmosphere.
0:20:28 > 0:20:29Changing levels of moisture,
0:20:29 > 0:20:33whether it's evaporation or condensation, change temperature.
0:20:33 > 0:20:37That changes pressure, that changes the wind speed and direction.
0:20:37 > 0:20:39So everything is hopelessly interrelated.
0:20:39 > 0:20:42How do we unscramble this Gordian knot?
0:20:43 > 0:20:46There was one man who decided to take it on.
0:20:50 > 0:20:54Lewis Fry Richardson was quite a remarkable mathematician.
0:20:54 > 0:21:00He was born in Newcastle in 1881 to a Quaker family.
0:21:00 > 0:21:05He studied mathematics at Cambridge University, getting a first,
0:21:05 > 0:21:07and then had various jobs,
0:21:07 > 0:21:10until he was offered a position in the Met Office.
0:21:11 > 0:21:14Richardson's great-nephew remembers him
0:21:14 > 0:21:18as a scientist interested in explaining everything.
0:21:18 > 0:21:22Even when he poured the water out in a glass and it slightly spilled,
0:21:22 > 0:21:25he then told us why the water did spill or didn't spill,
0:21:25 > 0:21:27depending exactly on how the water went over.
0:21:27 > 0:21:30So everything, everything was studied.
0:21:30 > 0:21:35In the First World War, Richardson had a crisis of conscience.
0:21:36 > 0:21:40He was working for the Met Office, but it was helping fight a war.
0:21:42 > 0:21:46Because he was a pacifist, he didn't want to get involved in fighting,
0:21:46 > 0:21:49nor did he want his science to be used in fighting.
0:21:49 > 0:21:55So he then resigned and joined the Quakers' Friends Ambulance Unit.
0:21:58 > 0:22:01Richardson had decided to help those suffering in war.
0:22:04 > 0:22:06He worked on the front line,
0:22:06 > 0:22:09driving an ambulance in extremely dangerous conditions.
0:22:13 > 0:22:17Between shifts, lodged in a freezing cold billet, he carried out one
0:22:17 > 0:22:22of the most remarkable metrological experiments ever attempted.
0:22:23 > 0:22:26Richardson brought these with him to the front.
0:22:26 > 0:22:30They're weather charts of northern Europe, taken on a specific time,
0:22:30 > 0:22:32on a specific day and the data had been collected
0:22:32 > 0:22:36by an international conference of meteorologists.
0:22:36 > 0:22:39What these charts did was to give Richardson an idea
0:22:39 > 0:22:42of the weather at a very specific time.
0:22:42 > 0:22:46But what he wanted to do was predict the weather a few hours after this.
0:22:46 > 0:22:49It wasn't a forecast as such, more of an exercise to see
0:22:49 > 0:22:51if his methods worked.
0:22:53 > 0:22:57Richardson had decided the only way to solve the equations
0:22:57 > 0:23:01of weather was to break them down into smaller calculations,
0:23:01 > 0:23:03each one looking at a part of the problem.
0:23:08 > 0:23:11He began by simplifying this map
0:23:11 > 0:23:15and drew a series of squares over northern Europe.
0:23:15 > 0:23:18What he wanted to do was see if his mathematical equations
0:23:18 > 0:23:22could predict the weather in this central area of Germany.
0:23:23 > 0:23:28He then entered his data into these computing forms, all 23 of them.
0:23:28 > 0:23:32And he used these to carry out even more calculations.
0:23:32 > 0:23:35He calculated how winds might affect air pressure,
0:23:35 > 0:23:39how air pressure might affect air density and temperature.
0:23:39 > 0:23:42He took into account the curvature of the earth,
0:23:42 > 0:23:44radiation from the sun and from the ground,
0:23:44 > 0:23:47he even had a calculation to work out
0:23:47 > 0:23:51how piles of dead leaves might move heat and moisture through the air.
0:23:53 > 0:23:57Temperature in the soil, latent heat of evaporation,
0:23:57 > 0:24:01character of vegetation, thermal conductivity,
0:24:01 > 0:24:03accumulation of sensible heat,
0:24:03 > 0:24:06the flux of sensible heat, sheer stress.
0:24:06 > 0:24:08The detail in here is incredible.
0:24:09 > 0:24:13The work was so complicated, it took him two years -
0:24:13 > 0:24:16half the First World War - to complete it.
0:24:17 > 0:24:21It's been estimated that Richardson had to solve 60,000 equations
0:24:21 > 0:24:23to get to his prediction.
0:24:23 > 0:24:26And he did it all by hand, on the Western Front,
0:24:26 > 0:24:29in between shifts as an ambulance driver.
0:24:31 > 0:24:34It was the world's first attempt at what's now
0:24:34 > 0:24:37known as a numerical forecast.
0:24:37 > 0:24:40And unfortunately, it was a complete failure.
0:24:40 > 0:24:42THUNDER CRASHES
0:24:43 > 0:24:49Now, one of his key results was that the pressure would change
0:24:49 > 0:24:53over the six-hour period following the observations.
0:24:53 > 0:24:57It would change by 145 millibars.
0:24:57 > 0:24:59Now, this is an astronomical figure.
0:24:59 > 0:25:03It's 100 times bigger than anything realistic.
0:25:03 > 0:25:05THUNDER CRASHES
0:25:05 > 0:25:09It's the equivalent of a hurricane the size of which has never
0:25:09 > 0:25:12happened before or since appearing out of nowhere in Germany.
0:25:18 > 0:25:21It seemed either his maths or his method were wrong.
0:25:24 > 0:25:26But Professor Lynch decided to go over
0:25:26 > 0:25:28Richardson's calculations again.
0:25:31 > 0:25:34So, some years ago, I thought it would be very
0:25:34 > 0:25:39interesting to replicate his work using a computer and sure enough,
0:25:39 > 0:25:45after a very short period, the computer produced the number 145.
0:25:48 > 0:25:51So he came up with the same result as Richardson,
0:25:51 > 0:25:53proving his maths was right.
0:25:56 > 0:25:58The real problem lay in the original data.
0:26:00 > 0:26:03Now, Richardson didn't realise this.
0:26:03 > 0:26:11His initial data was essentially corrupted by spurious noise.
0:26:11 > 0:26:16So it was a matter of making small but subtle alterations
0:26:16 > 0:26:21to the initial fields and when this subtle adjustment was made
0:26:21 > 0:26:25and the forecast was rerun, the change in pressure
0:26:25 > 0:26:29was reduced to something less than one millibar in six hours.
0:26:29 > 0:26:32Which, of course, is a realistic number.
0:26:32 > 0:26:36So, if Richardson had made some adjustments to his original data,
0:26:36 > 0:26:39his forecast could have been much more accurate.
0:26:43 > 0:26:44But there was another problem.
0:26:44 > 0:26:48You could never do these calculations fast enough to predict
0:26:48 > 0:26:50the weather before it happened.
0:26:50 > 0:26:52But Richardson had an answer to that, too.
0:26:54 > 0:26:56After the war, Richardson published this book
0:26:56 > 0:26:59and in here there's an extraordinary passage about something
0:26:59 > 0:27:02he dreamed up called the forecast factory.
0:27:03 > 0:27:06The forecast factory was Richardson's
0:27:06 > 0:27:08strange solution to the problem.
0:27:09 > 0:27:12It's so colourful a concept,
0:27:12 > 0:27:14it's inspired works of art in the years since.
0:27:18 > 0:27:22This was painted by Stephen Conlin in 1986.
0:27:22 > 0:27:25It gives us a vivid representation of what Richardson
0:27:25 > 0:27:28described in his book.
0:27:28 > 0:27:31You can see that Richardson described the round theatre,
0:27:31 > 0:27:34something like the Albert Hall, but painted with countries all over,
0:27:34 > 0:27:36to make it look like the planet earth.
0:27:37 > 0:27:41Around the outside of the globe are a series of boxes filled with
0:27:41 > 0:27:44people calculating equations for their part of the world
0:27:44 > 0:27:46and controlling all of them in the middle of the globe
0:27:46 > 0:27:48is the conductor,
0:27:48 > 0:27:51and he's making sure everyone's doing their job at the right time.
0:27:51 > 0:27:54On one side, you can see he's beaming some red light,
0:27:54 > 0:27:57which shows that those people are making their calculations a bit
0:27:57 > 0:28:00too quickly. On the other side, he's beaming some blue light,
0:28:00 > 0:28:04meaning they're making their calculations a bit too slowly.
0:28:05 > 0:28:09Outside the globe, there's actually people having a game of football.
0:28:09 > 0:28:12Because Richardson was clear, he said that people calculating
0:28:12 > 0:28:15the movement of the air should also be allowed to enjoy it.
0:28:17 > 0:28:19For Richardson, this was a fantasy.
0:28:19 > 0:28:22And even to us, it looks highly unrealistic.
0:28:22 > 0:28:25But it was actually a glimpse into the future,
0:28:25 > 0:28:30because what Richardson had dreamt up here was essentially a computer.
0:28:32 > 0:28:35But the data-crunching powers of a modern computer
0:28:35 > 0:28:38were still years ahead.
0:28:38 > 0:28:42I'd think the significance of what Richardson did can be seen
0:28:42 > 0:28:45by reflecting on what we actually do today.
0:28:45 > 0:28:48We assemble the observations, we analyse them,
0:28:48 > 0:28:51assimilate satellite data and so on,
0:28:51 > 0:28:54but the method of solving the equations is essentially
0:28:54 > 0:28:59of the same character as the method which Richardson invented.
0:29:03 > 0:29:05Richardson may have been a visionary,
0:29:05 > 0:29:09but it was clear that using maths was, for now, impossible.
0:29:11 > 0:29:15What was needed was a workable model to forecast the weather
0:29:15 > 0:29:17with some kind of confidence.
0:29:25 > 0:29:28And here, in the northernmost country in Europe,
0:29:28 > 0:29:31a major breakthrough would provide just such a model.
0:29:33 > 0:29:35Bergen is a city on the coast of Norway.
0:29:36 > 0:29:39Often battered by storms and low-pressure systems,
0:29:39 > 0:29:42it's an ideal place to study the weather.
0:29:44 > 0:29:49Even the local geography makes it a meteorologist's paradise.
0:29:51 > 0:29:55And so, here at the west coast of Norway, in Bergen here,
0:29:55 > 0:29:59we get the weather systems coming in and here
0:29:59 > 0:30:02they are well-behaved in the sense that they have very distinct
0:30:02 > 0:30:06structures, they have not been blurred or disturbed by
0:30:06 > 0:30:09big modern changes or the heat-land-sea contrast,
0:30:09 > 0:30:13so they come in here and we can monitor
0:30:13 > 0:30:17or measure these features very well.
0:30:21 > 0:30:24A century ago, some extraordinary work was carried out
0:30:24 > 0:30:26at the Geographical Institute in Bergen.
0:30:30 > 0:30:34A scientist called Wilhelm Bjorknes came here in 1917,
0:30:38 > 0:30:42and once again, it was human catastrophe that drove
0:30:42 > 0:30:44the next breakthrough in forecasting.
0:30:45 > 0:30:50Fisheries was a quite important, and still are important,
0:30:50 > 0:30:53activity and source of income in Norway.
0:30:54 > 0:30:58And at that time, when Bjorknes came here,
0:30:58 > 0:31:03they knew about several incidents where fishermen deceased
0:31:03 > 0:31:07and the boat sank due to unexpected weather, so to speak,
0:31:07 > 0:31:11so Bjorknes immediately saw that there was a need
0:31:11 > 0:31:13for weather forecasts.
0:31:14 > 0:31:19Bringing together all the data, they set about tackling the big question.
0:31:19 > 0:31:21How do low pressure systems work?
0:31:23 > 0:31:26What Bjorknes and his clever students...
0:31:26 > 0:31:30They put together this information and they came up with
0:31:30 > 0:31:33the pattern or the anatomy of the weather systems.
0:31:35 > 0:31:39They discovered two crucial features inside a depression.
0:31:39 > 0:31:41The warm front and the cold front.
0:31:46 > 0:31:49The theory of weather fronts is something every meteorology student
0:31:49 > 0:31:52now learns, even 100 years later.
0:31:52 > 0:31:56I'm back at my old university, Imperial College London,
0:31:56 > 0:31:58to take a look at today's weather map.
0:31:59 > 0:32:02OK, Jo, so we have a map of north-west Europe here. There's the UK.
0:32:02 > 0:32:06The Arctic's somewhere up there, so that's north, Greenland.
0:32:06 > 0:32:08What else are we looking at on this map?
0:32:08 > 0:32:10So, you've chosen a very interesting day to come.
0:32:10 > 0:32:12You can see it looks like a real mass,
0:32:12 > 0:32:15but there's features on here that you'll see in any weather map,
0:32:15 > 0:32:18and particularly you'll see that high pressure's marked with a H
0:32:18 > 0:32:21and you'll see the low pressure's marked with an L.
0:32:21 > 0:32:22And you'll also see these features,
0:32:22 > 0:32:25these lines with marks on, which are the fronts.
0:32:25 > 0:32:27Perhaps I could show you a rather simpler version
0:32:27 > 0:32:29on the blackboard here.
0:32:31 > 0:32:35So, if I stylise the low pressure system as a circle, like this...
0:32:36 > 0:32:38And here's the low in the middle here.
0:32:38 > 0:32:40And associated with the low pressure,
0:32:40 > 0:32:41you get these frontal systems.
0:32:43 > 0:32:45And here's the cold front.
0:32:47 > 0:32:49And the cold air's coming in from the north.
0:32:49 > 0:32:51And here's the warm front.
0:32:52 > 0:32:54And the warm air's coming in from the south.
0:32:54 > 0:32:57So, this essentially is the structure that was discovered
0:32:57 > 0:32:59by the Norwegian school in Bergen,
0:32:59 > 0:33:02and it's associated with the cold air in the north
0:33:02 > 0:33:05and the warm air in the south and it's where these two air masses
0:33:05 > 0:33:08meet that you get the low pressure and the fronts.
0:33:08 > 0:33:11- And this is where the weather happens, at these fronts? - That's right.
0:33:11 > 0:33:13So, over here we've got a fluid dynamics experiment
0:33:13 > 0:33:16which is going to illustrate what happens in a front.
0:33:16 > 0:33:19So, we're going to illustrate using water what happens in the air.
0:33:19 > 0:33:21How do the things relate?
0:33:21 > 0:33:25Well, of course, air is a fluid and it's flowing, and so is water.
0:33:25 > 0:33:28And what we're going to do is remove the divider between the two
0:33:28 > 0:33:30- and see what happens. - OK. Let's do it.
0:33:34 > 0:33:37- Cold water on the left, hot water on the right.- That's right.
0:33:37 > 0:33:40So, what we expect to see...
0:33:40 > 0:33:43is the cold water flowing underneath the hot water.
0:33:44 > 0:33:47So, it's just like in the frontal system.
0:33:47 > 0:33:50And the clouds would be forming between those two layers.
0:33:52 > 0:33:57'As the warmer air rises, it's cooling, causing clouds and rain.
0:33:58 > 0:34:01'The air masses meet along a turbulent boundary,
0:34:01 > 0:34:04'like two armies clashing along a front.
0:34:05 > 0:34:08'That's why the Bergen School called them fronts.
0:34:08 > 0:34:10'It's an echo from a generation
0:34:10 > 0:34:13'still scarred by the First World War.
0:34:17 > 0:34:21'The theory of fronts showed that Ley was right about cirrus
0:34:21 > 0:34:22'clouds decades before.
0:34:24 > 0:34:27'Different types of clouds form at different stages
0:34:27 > 0:34:29'of the development of fronts.
0:34:30 > 0:34:33'And we now know that cirrus clouds are usually the first
0:34:33 > 0:34:36'to develop as a warm front advances.
0:34:39 > 0:34:43'The theory also helps explain why Britain has such varied weather.'
0:34:45 > 0:34:48The UK sits right at the place where a number of different
0:34:48 > 0:34:50types of air masses meet.
0:34:50 > 0:34:53There's the polar air masses coming roughly from the north,
0:34:53 > 0:34:57the continental air masses from the east, the tropical air masses
0:34:57 > 0:35:01from the south and the maritime air masses coming from the west.
0:35:04 > 0:35:08Over the course of the British year, different types of air masses
0:35:08 > 0:35:11meet with varying temperatures and humidity.
0:35:13 > 0:35:17Generating the changeable weather we're all so familiar with.
0:35:20 > 0:35:22So, with the Bergen School,
0:35:22 > 0:35:25meteorologists finally had a way of predicting the weather in Europe
0:35:25 > 0:35:28and North America and those latitudes all round the world,
0:35:28 > 0:35:31which are all dominated by weather fronts.
0:35:37 > 0:35:39Now, the next frontier of forecasting awaited.
0:35:42 > 0:35:46In the years after the First World War, on the other
0:35:46 > 0:35:50side of the world, meteorologists were facing up to another challenge.
0:35:51 > 0:35:55Trying to unpick the complex, interlinked nature
0:35:55 > 0:35:56of the world's climate.
0:35:58 > 0:36:01Across the Indian subcontinent, flooding, drought
0:36:01 > 0:36:05and other natural disasters kill more people than any war.
0:36:07 > 0:36:10Even now, extreme weather events are hard to predict.
0:36:15 > 0:36:17This is Professor Ram Babu Singh.
0:36:19 > 0:36:22He and his students have set up a simple weather station
0:36:22 > 0:36:25on top of the campus buildings at Delhi University.
0:36:26 > 0:36:29Here we can gauge the temperature,
0:36:29 > 0:36:32the latest humidity, rainfall
0:36:32 > 0:36:35wind direction, wind velocity.
0:36:35 > 0:36:39This is a very small initiative, but through this
0:36:39 > 0:36:45we want to develop the culture of monitoring weather,
0:36:45 > 0:36:49you know, so that this will become the mass movement in our country.
0:36:51 > 0:36:54This data could help predict probably the most important
0:36:54 > 0:36:59and mysterious climactic phenomenon in India - the monsoon.
0:37:02 > 0:37:06As you know, India has more than one billion population,
0:37:06 > 0:37:10and for feeding them, we need agricultural production.
0:37:10 > 0:37:14The monsoon is very, very important for our country.
0:37:16 > 0:37:19The monsoon rains are brought to India by seasonal winds.
0:37:21 > 0:37:23Sometimes they fail to come
0:37:23 > 0:37:25and the consequences can be catastrophic.
0:37:27 > 0:37:30Continuous, for two years, failure of rainfall
0:37:30 > 0:37:35will bring tremendous damage to our society
0:37:35 > 0:37:39through loss, through reduction of agricultural production.
0:37:41 > 0:37:43Under the British Empire,
0:37:43 > 0:37:45monsoon failures caused horrific suffering.
0:37:47 > 0:37:51There were fast famines with millions of deaths.
0:37:55 > 0:37:59By the time of the First World War, the scientist tasked with
0:37:59 > 0:38:03trying to understand why it was happening was called Gilbert Walker.
0:38:04 > 0:38:06He was head of the Indian Meteorological Department
0:38:06 > 0:38:09and he had some unusual interests.
0:38:10 > 0:38:12He would throw boomerangs and projectiles around,
0:38:12 > 0:38:15even in front of the Viceroy of India.
0:38:16 > 0:38:19Sir Gilbert Walker was really interested in the dynamics
0:38:19 > 0:38:22of throwing sticks, of spears, of boomerangs.
0:38:23 > 0:38:26And all those sort of things, and to try and understand what were
0:38:26 > 0:38:30the fundamental processes involved with aerodynamics?
0:38:35 > 0:38:39Walker's fascination with dynamics made him an ideal choice
0:38:39 > 0:38:41to tackle one of the most complicated
0:38:41 > 0:38:43scientific conundrums of the age.
0:38:44 > 0:38:49Planetary dynamics - how does the climate work on a global scale?
0:38:51 > 0:38:53During the First World War he was left with the Indian
0:38:53 > 0:38:56clerks in his department, a mass of people.
0:38:56 > 0:38:59And because there was all this information, predecessors,
0:38:59 > 0:39:02he had been looking to try and forecast the monsoon.
0:39:02 > 0:39:04What he did was to pull all this information,
0:39:04 > 0:39:06all the hydrological and meteorological data
0:39:06 > 0:39:07that he had round the world,
0:39:07 > 0:39:10and basically to create a human computer,
0:39:10 > 0:39:15getting his clerks to work together in mass to do correlations
0:39:15 > 0:39:17of all sorts between these variables.
0:39:21 > 0:39:24They made some extremely significant breakthroughs.
0:39:26 > 0:39:28What he basically found with these Indian clerks
0:39:28 > 0:39:32was that there was a pressure fluctuation,
0:39:32 > 0:39:36which you called an oscillation, between the Indo-Australasian region
0:39:36 > 0:39:40and in the southeastern Pacific region of the globe.
0:39:42 > 0:39:44So, when the pressure is high over the Pacific,
0:39:44 > 0:39:47it's low over India and vice versa.
0:39:49 > 0:39:52The seesaw in pressure is one of the elements in the dynamics
0:39:52 > 0:39:54of the climate system over the globe -
0:39:54 > 0:39:58its linkages to monsoonal systems like in India.
0:39:58 > 0:40:01It's not one-to-one in India but it certainly has an impact.
0:40:03 > 0:40:07And so the whole system of the rainfall is related to
0:40:07 > 0:40:10the fluctuation in pressure that Walker discovered.
0:40:12 > 0:40:15Walker's efforts added another piece to the picture
0:40:15 > 0:40:17of our understanding of global dynamics,
0:40:17 > 0:40:21and I think he's a person that we really need to really give
0:40:21 > 0:40:25high praise to, for his efforts on understanding the climate system.
0:40:29 > 0:40:33In the 1920s and 1930s, meteorologists were beginning
0:40:33 > 0:40:37to realise the global, interlinked nature of our climate.
0:40:38 > 0:40:42But their understanding of our hugely complex atmosphere
0:40:42 > 0:40:43was still limited.
0:40:43 > 0:40:47Again, it would take a world war to provide more investment,
0:40:47 > 0:40:50more challenges and more breakthroughs.
0:40:50 > 0:40:53It would also provide meteorologists with their toughest test yet.
0:40:59 > 0:41:04When the war broke out in 1939, the Met Office was once more mobilised.
0:41:06 > 0:41:10They set up a top-secret camp outside London in Dunstable.
0:41:13 > 0:41:16They faced an extremely difficult task,
0:41:16 > 0:41:18gathering data in wartime conditions
0:41:18 > 0:41:21with the technology available at the time.
0:41:24 > 0:41:26The Met Office had thermometers,
0:41:26 > 0:41:28had barometers.
0:41:28 > 0:41:33They may have had a weather vane, a wind speed indicator
0:41:33 > 0:41:36and a device for measuring humidity.
0:41:36 > 0:41:39And then they would look out the window
0:41:39 > 0:41:41and see what it was doing and they also had...
0:41:43 > 0:41:44..the wet finger.
0:41:46 > 0:41:47As the war progressed,
0:41:47 > 0:41:50a sophisticated system for gathering data was developed.
0:41:52 > 0:41:56This included weather ships taking readings out at sea.
0:41:56 > 0:42:00And they also had men aboard weather reconnaissance flights.
0:42:00 > 0:42:03Long, lonely flights over the north Atlantic.
0:42:03 > 0:42:06That gave them a pretty accurate picture
0:42:06 > 0:42:08of what was actually happening.
0:42:11 > 0:42:15Colin Mentz is one of the few Met Air Observers still alive.
0:42:16 > 0:42:19As a teenager, he flew on hundreds of reconnaissance flights
0:42:19 > 0:42:23with the RAF, and later in American B-17s.
0:42:25 > 0:42:29These are some of the chaps with me.
0:42:29 > 0:42:31That's me. Tallest of the lot.
0:42:32 > 0:42:36I think the longest flight I ever did was about 16 and a half hours.
0:42:37 > 0:42:39I used to enjoy it.
0:42:39 > 0:42:42All the time you were keen on looking
0:42:42 > 0:42:44out of the window at the weather.
0:42:45 > 0:42:46Because you had to make notes
0:42:46 > 0:42:49and code the stuff up
0:42:49 > 0:42:52to send back, otherwise your flight was wasted.
0:42:54 > 0:42:57This is a Met Office weather chart from 1944.
0:42:59 > 0:43:02It shows readings which Colin sent back during a flight
0:43:02 > 0:43:04from Cornwall out into the Atlantic.
0:43:07 > 0:43:11His data was highly important as he was one of the few observers
0:43:11 > 0:43:13Dunstable had out to the west.
0:43:15 > 0:43:16But it was dangerous work.
0:43:18 > 0:43:2223 Met Air Observers were killed during World War II.
0:43:23 > 0:43:25PLANE ENGINE ROARS
0:43:26 > 0:43:32The most dangerous part was flying at 10, 20, 30 feet above the sea.
0:43:33 > 0:43:36It's sometimes very rough.
0:43:37 > 0:43:38So, were you ever frightened?
0:43:40 > 0:43:42No. Not that I can think of.
0:43:43 > 0:43:44Eh...
0:43:44 > 0:43:49I thought sometimes that, "I wonder if we'll get back all right."
0:43:58 > 0:44:01The Allied forecasting system got many predictions right
0:44:01 > 0:44:03and saved lives.
0:44:04 > 0:44:07But they still didn't really understand some crucial parts
0:44:07 > 0:44:10of the higher atmosphere, and when they got things wrong,
0:44:10 > 0:44:12the consequences could be dire.
0:44:15 > 0:44:17In the winter of 1943,
0:44:17 > 0:44:21Bomber Command launched a series of raids on Berlin.
0:44:24 > 0:44:27On the night of 24 March 1944,
0:44:27 > 0:44:33a huge fleet of 811 aircraft set off for Berlin.
0:44:37 > 0:44:40The original idea was to fly the planes over Denmark
0:44:40 > 0:44:43and the Baltic Sea, drop the bombs on Berlin
0:44:43 > 0:44:45and then come back as quickly as possible,
0:44:45 > 0:44:49avoiding the Ruhr industrial area, which was heavily defended.
0:44:51 > 0:44:54Predicting upper air speeds for a bombing run like this was
0:44:54 > 0:44:57one of the toughest tasks for forecasters.
0:44:59 > 0:45:03That night, the prediction was for winds of around 45mph.
0:45:05 > 0:45:08The first wave of bombers took wind finders,
0:45:08 > 0:45:11weather observers who sent back reports.
0:45:14 > 0:45:16By the time the fleet reached Denmark,
0:45:16 > 0:45:18the wind finders were reporting extraordinary winds
0:45:18 > 0:45:23coming from the North, air currents up to 130mph.
0:45:23 > 0:45:25This was far, far more than expected.
0:45:28 > 0:45:33In fact, we now know the planes were encountering jet stream winds.
0:45:33 > 0:45:36These are the very same winds which William Clement Ley
0:45:36 > 0:45:39had discovered 50 years before.
0:45:39 > 0:45:44But still, meteorology hadn't properly understood the phenomenon.
0:45:44 > 0:45:48That night, the results were catastrophic.
0:45:48 > 0:45:52Even before the Allied planes got to Berlin, they were scattered,
0:45:52 > 0:45:55off-target and in disarray.
0:45:55 > 0:45:58Then, when they turned westwards to head back to Britain,
0:45:58 > 0:46:00the German night fighters were lying in wait.
0:46:00 > 0:46:02The Allies were sitting ducks.
0:46:03 > 0:46:0672 bombers were destroyed.
0:46:07 > 0:46:09Over 500 men were lost.
0:46:11 > 0:46:14That night was known for ever afterwards by the RAF
0:46:14 > 0:46:17as "the night of the big winds".
0:46:19 > 0:46:23This disastrous night was a stern warning for weather forecasters
0:46:23 > 0:46:27who had to accept their limitations as well as their successes.
0:46:27 > 0:46:30And coming up was the most important forecast of all.
0:46:30 > 0:46:32D-Day.
0:46:39 > 0:46:43Throughout 1944, the Allies were assembling a colossal
0:46:43 > 0:46:46invasion force around the coast of Britain.
0:46:47 > 0:46:5011,000 aircraft.
0:46:50 > 0:46:526,000 sea vessels.
0:46:52 > 0:46:54150,000 soldiers.
0:46:55 > 0:46:56Their target?
0:46:56 > 0:46:58The beaches of Normandy,
0:46:58 > 0:47:00100 miles in that direction.
0:47:10 > 0:47:12As overall military leader,
0:47:12 > 0:47:14Eisenhower needed an accurate forecast
0:47:14 > 0:47:16for the day he was to invade.
0:47:17 > 0:47:21But the Allies had developed a complicated forecasting structure
0:47:21 > 0:47:23with three centres.
0:47:24 > 0:47:27The admiralty had its forecasters.
0:47:27 > 0:47:30There was the Met Office at Dunstable.
0:47:31 > 0:47:35And the American Air Force had its forecasters, too.
0:47:36 > 0:47:39The forecasters in Dunstable made their predictions
0:47:39 > 0:47:43based on the theory of fronts, as pioneered by the Bergen School.
0:47:43 > 0:47:46The US Air Force, though, had different ideas
0:47:46 > 0:47:48under its chief, Irving P. Krick.
0:47:53 > 0:47:57Irving Krick was in the weather business to make money.
0:47:57 > 0:48:01And he used his position in the US Air Force
0:48:01 > 0:48:03for self-promotion.
0:48:04 > 0:48:06He was bombastic...
0:48:07 > 0:48:11he was absolutely convinced that he was right.
0:48:12 > 0:48:18His reputation among other American meteorologists...
0:48:18 > 0:48:20He is considered a charlatan.
0:48:21 > 0:48:24Krick advocated a highly unusual method to predict the weather.
0:48:25 > 0:48:32Analog theory is the idea that a weather map from history...
0:48:33 > 0:48:40is the key to understanding the weather of tomorrow...
0:48:42 > 0:48:44because it's based on the notion
0:48:44 > 0:48:47that weather repeats itself in cycles.
0:48:48 > 0:48:50And it does not.
0:48:52 > 0:48:56Irving Krick believed that he could forecast the weather almost anywhere
0:48:56 > 0:49:01in the world for a month in advance, because of his analog system.
0:49:03 > 0:49:07With different forecasting centres using different methods,
0:49:07 > 0:49:13one man was given the job of melding the forecasts into a single report.
0:49:13 > 0:49:17A Scotsman called Group Captain James Stagg.
0:49:22 > 0:49:25Stagg was an interesting character.
0:49:26 > 0:49:33On the outside, his shell was as hard as a conker shell.
0:49:33 > 0:49:37On the inside, he was filled with self-doubt.
0:49:37 > 0:49:39Would he get it right?
0:49:41 > 0:49:45The Allies only had a few dates on which it was possible for them
0:49:45 > 0:49:49to invade. They needed the moon and the tides to be perfect.
0:49:49 > 0:49:51The first date they set was June 5th.
0:49:54 > 0:49:55As the date neared,
0:49:55 > 0:49:59Stagg was under extreme pressure to get his forecast right.
0:49:59 > 0:50:02One general even said to him that if he got the forecast wrong,
0:50:02 > 0:50:05he'd be strung up from the nearest lamppost.
0:50:08 > 0:50:10This is a weather map created using original data
0:50:10 > 0:50:12from those crucial few days.
0:50:12 > 0:50:15It shows the situation at the end of May.
0:50:15 > 0:50:18What you can see is that Britain generally has good weather
0:50:18 > 0:50:20because of a high-pressure system.
0:50:20 > 0:50:22But look out to the west
0:50:22 > 0:50:24and you can see some low-pressure systems developing.
0:50:24 > 0:50:26They're the counterclockwise winds.
0:50:27 > 0:50:32This highly complicated weather map divided the scientists.
0:50:32 > 0:50:35The Dunstable forecasters were very worried about the lows.
0:50:37 > 0:50:39But Irving Krick was confidently predicting
0:50:39 > 0:50:42that the weather would be good enough to invade.
0:50:44 > 0:50:47So it was that over those few days,
0:50:47 > 0:50:50a tiny weather station on the west coast of Ireland became
0:50:50 > 0:50:56the most important meteorological centre in the entire world.
0:50:58 > 0:51:01Blacksod Point is a remote spot overlooking the Atlantic.
0:51:05 > 0:51:08Vincent Sweeney keeps the lighthouse,
0:51:08 > 0:51:10just like his father, Ted, before him.
0:51:13 > 0:51:16My dad lived here and he was in the lighthouse,
0:51:16 > 0:51:18he was the attendant at the lighthouse here in Blacksod
0:51:18 > 0:51:21before he retired in 1981. And then I took over.
0:51:23 > 0:51:25The lighthouse is situated in a vital area
0:51:25 > 0:51:28for collecting weather data.
0:51:28 > 0:51:31It's a strategic location into the North Atlantic.
0:51:31 > 0:51:38It's poised right on the tip and any weather systems that come over,
0:51:38 > 0:51:39they hit us first.
0:51:42 > 0:51:45Blacksod's position made it a very important source
0:51:45 > 0:51:47of data for Dunstable,
0:51:47 > 0:51:51who had an information-sharing arrangement with the Irish Met.
0:51:54 > 0:51:57Just down the road was where the data was collected.
0:52:00 > 0:52:04This house here was where the weather station was.
0:52:04 > 0:52:07In the garden of the house, as you can see,
0:52:07 > 0:52:10where the daffodils are, there, there was some weather instruments,
0:52:10 > 0:52:13so this is where all the readings came.
0:52:14 > 0:52:16Vincent's dad has passed away.
0:52:16 > 0:52:19But his mum Maureen is still alive.
0:52:19 > 0:52:24She's 92 years old and still lives at Blacksod Point.
0:52:24 > 0:52:26'What was it like during the war around here?'
0:52:26 > 0:52:28It was quite enough, you know.
0:52:30 > 0:52:34We had plenty of planes overhead, you know?
0:52:34 > 0:52:36But the thing is, we didn't know whether
0:52:36 > 0:52:39- they were British or German! - SHE LAUGHS
0:52:39 > 0:52:41It was a bit frightening, yeah.
0:52:41 > 0:52:43Especially at night.
0:52:46 > 0:52:49D-Day was approaching.
0:52:49 > 0:52:53And the family were asked to take readings every hour.
0:52:53 > 0:52:59On the hour, every hour, night and day, Sunday and Monday.
0:52:59 > 0:53:04We were told that all reports were the first to show any change
0:53:04 > 0:53:08coming in for good weather or bad weather.
0:53:10 > 0:53:13On the crucial night, the 3rd of June,
0:53:13 > 0:53:16it was Maureen's turn to get up in the middle of the night.
0:53:19 > 0:53:23She measured 4-6 winds and a rapidly dropping barometer.
0:53:23 > 0:53:26A sign of approaching bad weather.
0:53:29 > 0:53:33The figures alarmed Dunstable and they rang Maureen back.
0:53:35 > 0:53:39We took the weather in the ordinary way and passed it on.
0:53:39 > 0:53:43I wasn't told anything until we got it back again, saying,
0:53:43 > 0:53:45"Please check and repeat."
0:53:47 > 0:53:49I went back again and I checked.
0:53:49 > 0:53:51But it was right.
0:53:51 > 0:53:53It HAD dropped.
0:53:53 > 0:53:57This is the situation on the morning of June the 3rd.
0:53:57 > 0:54:00There's Blacksod Bay on the west coast of Ireland,
0:54:00 > 0:54:04where the air pressure is dropping and the winds are on the rise.
0:54:04 > 0:54:08As the day progresses, the low gets deeper, the winds get faster
0:54:08 > 0:54:11and the low-pressure weather system starts to move
0:54:11 > 0:54:13north-east across the Irish coast.
0:54:14 > 0:54:18At 4am on the 4th of June, with less than a day to go,
0:54:18 > 0:54:21Stagg headed into Eisenhower's office.
0:54:22 > 0:54:24He walked into the room full of generals
0:54:24 > 0:54:27and told them that the conditions in the Channel would be too choppy,
0:54:27 > 0:54:30too much cloud, too many high waves.
0:54:30 > 0:54:32The invasion had to be called off.
0:54:37 > 0:54:42The future of the war hung on what Eisenhower did next.
0:54:44 > 0:54:47You know, the weather outside was reasonably good.
0:54:47 > 0:54:51So everybody was a little perplexed by that.
0:54:51 > 0:54:54But Eisenhower had taken measure of Stagg
0:54:54 > 0:54:59and he knew that he could rely on Stagg
0:54:59 > 0:55:03to give him completely unbiased information.
0:55:05 > 0:55:09Eisenhower agreed and postponed for a day.
0:55:09 > 0:55:15Some of the ships had already set sail and had to return to port.
0:55:15 > 0:55:19Stagg was dismayed for much of that day as the weather stayed calm.
0:55:19 > 0:55:22But that afternoon, the wind picked up
0:55:22 > 0:55:25and the bad weather that he'd predicted swept in.
0:55:27 > 0:55:33If the invasion had been held on the night of 4-5 June,
0:55:33 > 0:55:35as it was planned, it would have failed.
0:55:35 > 0:55:39The results would have been catastrophic
0:55:39 > 0:55:41for our own history.
0:55:43 > 0:55:47The next day, the weather improved and the invasion was launched.
0:55:49 > 0:55:50It was a success.
0:55:52 > 0:55:56The Allies gained a crucial foothold in German-occupied France.
0:55:58 > 0:56:03To think that so much hinged on a single weather forecast.
0:56:04 > 0:56:07GUNFIRE
0:56:09 > 0:56:11The D-Day forecast was a triumph.
0:56:11 > 0:56:14It showed that the theory of fronts could be used to predict
0:56:14 > 0:56:17the weather, at least for the short term.
0:56:17 > 0:56:21It was also a success for those meteorologists who understood
0:56:21 > 0:56:23that their science had limits.
0:56:26 > 0:56:29The Met Office camp at Dunstable is long gone.
0:56:30 > 0:56:32On the site now is a school.
0:56:33 > 0:56:37Staff and children here have set up a monument and a weather station.
0:56:39 > 0:56:4471 members of the Met Office died in World War II
0:56:44 > 0:56:45while on active service.
0:56:47 > 0:56:53As for Colin Mentz, he flew on D-Day itself.
0:56:53 > 0:56:57I can remember travelling over southern England,
0:56:57 > 0:57:01saw all the aircraft lined up on the airfields,
0:57:01 > 0:57:04and when we came back the next morning,
0:57:04 > 0:57:06the airfields were empty.
0:57:06 > 0:57:07They'd all gone.
0:57:07 > 0:57:14We got the message saying that the invasion of France had taken place.
0:57:16 > 0:57:18I turned to the skipper and said,
0:57:18 > 0:57:20"Do you want to go over and have a look, Skip?"
0:57:20 > 0:57:23- LAUGHING:- He didn't.
0:57:26 > 0:57:30Ted Sweeney now lies buried overlooking the Atlantic,
0:57:30 > 0:57:32where the D-Day depression first blew in.
0:57:36 > 0:57:39And Maureen is still contacted by veterans
0:57:40 > 0:57:43who've thanked her for getting her readings correct.
0:57:44 > 0:57:51Recently I was reading a piece in an English paper and had Eisenhower
0:57:51 > 0:57:56declared war that night or gone to war, it would have smashed America.
0:57:58 > 0:58:03- It said that. I should've kept that paper.- 'Yeah.'
0:58:03 > 0:58:06'So it was your weather report, your barometer reading...'
0:58:06 > 0:58:08Yeah, from Blacksod,
0:58:08 > 0:58:09above all places!
0:58:09 > 0:58:13- SHE LAUGHS - That ended the war!
0:58:15 > 0:58:17In the next episode:
0:58:17 > 0:58:20Richardson's dream becomes a reality
0:58:20 > 0:58:23in the face of some of weather's greatest challenges.
0:58:23 > 0:58:26Forecasting becomes a global enterprise,
0:58:26 > 0:58:29built on high technology.