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108-577: Chain Home , or CH for short, was the codename for the ring of coastal early warning radar stations built by the Royal Air Force (RAF) before and during the Second World War to detect and track aircraft. Initially known as RDF , and given the official name Air Ministry Experimental Station Type 1 ( AMES Type 1) in 1940, the radar units were also known as Chain Home for most of their life. Chain Home

216-468: A cathode-ray tube (CRT) to a directional Adcock antenna array, originally built by the RRS but now unused. The combined system, later known as huff-duff (from HF/DF, high frequency direction finding), allowed the almost instantaneous determination of the bearing of a signal. The Met Office began using it to produce storm warnings for aviators. During this period, Edward Appleton of King's College, Cambridge

324-551: A machinery of government change, the Met Office became part of the Department for Business, Innovation and Skills on 18 July 2011, and subsequently part of the Department for Business, Energy and Industrial Strategy following the merger of BIS and the Department of Energy and Climate Change on 14 July 2016. Although no longer part of the MOD, the Met Office maintains strong links with

432-476: A German newspaper with an image of a large radio antenna that had been installed on Feldberg in the same area. Although highly skeptical about claims of engine-stopping rays and death rays, the Air Ministry could not ignore them as they were theoretically possible. If such systems could be built, it might render bombers useless. If this were to happen, the night bomber deterrent might evaporate overnight, leaving

540-658: A breezy interview, Watson-Watt and Jock Herd stated the job was his if he could sing the Welsh national anthem . He agreed, but only if they would sing the Scottish one in return. They declined, and gave him the job. Starting with the BBC transmitter electronics, but using a new transmitter valve from the Navy, Bowen produced a system that transmitted a 25 kW signal at 6 MHz (50 metre wavelength), sending out 25 μs long pulses 25 times

648-408: A considerable number of mast and aerial systems". Several members of the team went on scouting trips with Watt to the north of Orfordness but found nothing suitable. Then Wilkins recalled having come across an interesting site about 10 mi (16 km) south of Orfordness, some time earlier while on a Sunday drive. He recalled it because it was some 70–80 ft (21–24 m) above sea level, which

756-429: A death ray was impossible but suggested radio could be used for long-range detection. In February 1935, a successful demonstration was arranged by placing a receiver near a BBC short wave transmitter and flying an aircraft around the area. Using commercial short wave radio hardware, Watt's team built a prototype pulsed transmitter and by June 1935 it detected an aircraft that happened to be flying past. Basic development

864-437: A distance of 5 kilometres (3.1 mi) from 98 to 105 °F (37 to 41 °C). To Watt's bemusement, Wilkins immediately surmised this was a question about a death ray. He made a number of back-of-the-envelope calculations demonstrating the amount of energy needed would be impossible given the state of the art in electronics. According to R. V. Jones , when Wilkins reported the negative results, Watt asked, "Well then, if

972-511: A few months of his joining the Committee, what had previously been an innovative and forward-looking group became riven with strife. It was strictly Lindemann versus the rest, with his hostility to radar and his insistence on totally impractical ideas about intercepting enemy aircraft by means of wires dangled from balloons, or by infrared, which at that time simply did not have the sensitivity to detect aircraft at long range. Churchill's backing meant

1080-790: A forecasting centre in Aberdeen , and offices in Gibraltar and on the Falklands . Other outposts lodge in establishments such as the MetOffice@Reading (formerly the Joint Centre for Mesoscale Meteorology) at University of Reading in Berkshire, the Joint Centre for Hydro-Meteorological Research (JCHMR) site at Wallingford in Oxfordshire, and there is a Met Office presence at Army and Air Force bases within

1188-585: A joint AMES-GPO group. The Treasury gave approval for full-scale deployment in August, and the first production contracts were sent out for 20 sets in November, at a total cost of £380,000. Installation of 15 of these sets was carried out in 1937 and 1938. In June 1938 a London headquarters was established to organize the rapidly growing force. This became the Directorate of Communications Development (DCD), with Watt named as

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1296-428: A receiver to give an early indication of approaching aircraft. Watt wrote back to the committee saying the death ray was extremely unlikely, but added: Attention is being turned to the still difficult, but less unpromising, problem of radio detection and numerical considerations on the method of detection by reflected radio waves will be submitted when required. The letter was discussed at the first official meeting of

1404-491: A second. Meanwhile, Wilkins and L.H. Bainbridge-Bell built a receiver based on electronics from Ferranti and one of the RRS CRTs. They decided not to assemble the system at the RRS for secrecy reasons. The team, now consisting of three scientific officers and six assistants, began moving the equipment to Orfordness on 13 May 1935. The receiver and transmitter were set up in old huts left over from World War I artillery experiments,

1512-446: A signal detectable at about 10 miles (16 km). They went on to suggest that the output power could be increased as much as ten times if the system operated in pulses instead of continuously, and that such a system would have the advantage of allowing range to the targets to be determined by measuring the time delay between transmission and reception on an oscilloscope . The rest of the required performance would be made up by increasing

1620-583: A speech on "The threat of Nazi Germany" in which he pointed out that the Royal Navy could not protect Britain from an enemy who attacked by air. Through the early 1930s, a debate raged within British military and political circles about strategic airpower. Baldwin's famous speech led many to believe the only way to prevent the bombing of British cities was to make a strategic bomber force so large it could, as Baldwin put it, "kill more women and children more quickly than

1728-410: A suitable pulsed transmitter. An engineer familiar with these concepts was needed. Edward George Bowen joined the team after responding to a newspaper advertisement looking for a radio expert. Bowen had previously worked on ionosphere studies under Appleton, and was well acquainted with the basic concepts. He had also used the RRS' RDF systems at Appleton's request and was known to the RRS staff. After

1836-581: A summary, the Global Annual to Decadal Climate Update is published each year. Until 2001 the Met Office hosted the Intergovernmental Panel on Climate Change working group, chaired by John Houghton , on climate science. In 2001 the working group moved to the National Oceanic and Atmospheric Administration . Due to the large amount of computation needed for Numerical Weather Prediction and

1944-418: A system could determine the angle to a target, it could not determine its range and provide a location in space. To do so, two such measurements would have to be made from different locations. Watt's huff-duff technique solved the problem of making rapid measurements, but the issue of coordinating the measurement at two stations remained, as did any inaccuracies in measurement or differences in calibration between

2052-502: A system was becoming increasingly pressing. In 1932, Winston Churchill and his friend, confidant and scientific advisor Frederick Lindemann travelled by car in Europe, where they saw the rapid rebuilding of the German aircraft industry. It was in November of that year that Stanley Baldwin gave his famous speech, stating that " The bomber will always get through ". In the early summer of 1934,

2160-700: Is also a network of 'upper air' stations, using radiosondes . The six main radiosonde stations in the UK are Camborne, Lerwick, Albemarle, Watnall, Castor Bay and Herstmonceux. Some stations have limited reporting times, while other report continuously, mainly RAF and Army Air Corps stations where a staffed met office is provided for military operations. The "standard" is a once-hourly reporting schedule, but automatic stations can often be "polled" as required, whilst stations at airfields report twice-hourly, with additional (often frequent in times of bad weather) special reports as necessary to inform airfield authorities of changes to

2268-439: Is greatly extended. This allows the radar to use high-frequency signals, offering high resolution, while still offering long range. A major exception to this rule are radars intended to warn of ballistic missile attacks, like BMEWS , as the high-altitude exo-atmospheric trajectory of these weapons allows them to be seen at great ranges even from ground-based radars. Met Office The Meteorological Office , abbreviated as

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2376-698: Is jointly staffed from both parent organisations and is based in the Operations Centre at the Met Office headquarters in Exeter. In Scotland this role is performed by the Scottish Flood Forecasting Service, a joint venture between the Scottish Environment Protection Agency (SEPA) and the Met Office. The Met Office makes seasonal and long range forecasts and distributes them to customers and users globally. The Met Office

2484-416: Is produced for pollutants and their typical health effects are shown in the following table. Decadal Predictions The Met Office coordinates the production and collation of decadal climate prediction from climate centres around the world as part of its responsibilities as World Meteorological Organisation Lead Centre for Annual to Decadal Climate Prediction . These predictions are updated each year and

2592-677: Is responsible for the area covering the British Isles , the north east Atlantic and Iceland . The VAAC were set up by the International Civil Aviation Organization (ICAO), an agency of the United Nations, as part of the International Airways Volcano Watch (IAVW). The London VAAC makes use of satellite images, plus seismic, radar and visual observation data from Iceland , the location of all of

2700-584: Is used daily to safely and economically route aircraft, particularly on long-haul journeys. The data provides details of wind speed and direction, air temperature, cloud type and tops, and other features. As part of its aviation forecast operation the Met Office operates the London Volcanic Ash Advisory Centre (VAAC). This provides forecasts to the aviation industry of volcanic ash clouds that could enter aircraft flight paths and impact aviation safety. The London VAAC, one of nine worldwide,

2808-544: The Chernobyl accident in 1986, but has since evolved into an all-purpose dispersion model capable of predicting the transport, transformation and deposition of a wide class of airborne materials. NAME is used operationally by the Met Office as an emergency response model as well as for routine air quality forecasting. Aerosol dispersion is calculated using the United Kingdom Chemistry and Aerosols model . The forecast

2916-591: The Met Office in a lab that was colocated at the National Physical Laboratory 's (NPL) Radio Research Section (RRS) at Ditton Park in Slough . Watt became interested in using the fleeting radio signals given off by lightning as a way to track thunderstorms , but existing RDF techniques were too slow to allow the direction to be determined before the signal disappeared. In 1922, he solved this by connecting

3024-558: The Met Office , is the United Kingdom's national weather and climate service. It is an executive agency and trading fund of the Department for Science, Innovation and Technology and is led by CEO Penelope Endersby , who took on the role as Chief Executive in December 2018 and is the first woman to do so. The Met Office makes meteorological predictions across all timescales from weather forecasts to climate change . The Met Office

3132-491: The North Atlantic Oscillation and winter climate for Europe and North America. One of the main media companies, ITV produce forecasts for ITV Weather using the Met Office's data and animated weather symbols. The BBC used to use Met Office forecasts for all of its output, but on 23 August 2015, it was announced that the BBC would be replacing the Met Office with MeteoGroup , a competing provider, as part of

3240-530: The Royal Netherlands Meteorological Institute (KNMI). The main role of the Met Office is to produce forecast models by gathering information from weather satellites in space and observations on earth, then processing it with a variety of models, based on a software package known as the unified model . The principal weather products for UK customers are 36-hour forecasts from the operational 1.5 km resolution UKV model covering

3348-923: The Unified model , the Met Office has had some of the most powerful supercomputers in the world. In November 1997 the Met Office supercomputer was ranked third in the world. Since 2012 the Met Office Contact Centre (known as the Weather Desk) has been part of Contact Centre Panel's 'Top 50 Companies for Customer Service' programme. In 2015 the Met Office won awards in the following categories: Reports (observations) from weather stations can be automatic (totally machine produced), semi-automatic (part-machine and part manual), or manual. Some stations produce manual observations during business hours and revert to automatic observations outside these times. Many stations feature "present weather" sensors, CCTV , etc. There

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3456-401: The acoustic mirror systems that had been in development for a decade were still limited to only 5 mi (8.0 km) range under most conditions, and were very difficult to use in practice. Work on mirror systems ended, and on 19 December 1935, a £60,000 contract for five RDF stations along the south-east coast was sent out, to be operational by August 1936. The only person not convinced of

3564-518: The gain of the antennas by making them very tall, focusing the signal vertically. The memo concluded with an outline for a complete station using these techniques. The design was almost identical to the CH stations that went into service. The letter was seized on by the Committee, who immediately released £4,000 to begin development. They petitioned Hugh Dowding , the Air Member for Supply and Research , to ask

3672-539: The 50 MW range by the 1960s. Since then, improvements in receiver electronics has greatly reduced the amount of signal needed to produce an accurate image, and in modern examples the transmitted power is much less; the AN/FPS-117 offers 250 nautical miles (460 km; 290 mi) range from 25 kW. EW radars are also highly susceptible to radar jamming and often include advanced frequency hopping systems to reduce this problem. The first early-warning radars were

3780-728: The British Chain Home , the German Freya , the US CXAM (Navy) and SCR-270 (Army), and the Soviet Union RUS-2  [ ru ] . By modern standards these were quite short range, typically about 100 to 150 miles (160 to 240 km). This "short" distance is a side effect of radio propagation at the long wavelengths being used at the time, which were generally limited to line-of-sight. Although techniques for long-range propagation were known and widely used for shortwave radio ,

3888-484: The British military with claims of having perfected some form of the fabled electric or radio " death ray ". Some turned out to be frauds and none turned out to be feasible. Around the same time, a series of stories suggested another radio weapon was being developed in Germany. The stories varied, with one common thread being a death ray, and another that used the signals to interfere with an engine's ignition system to cause

3996-564: The CH systems were used to detect V2 missile launches. UK radar systems were wound down after the war but the start of the Cold War led to the Chain Home radars being pressed into service in the new ROTOR system until replaced by newer systems in the 1950s. Only a few of the original sites remain. From the earliest days of radio technology, signals had been used for navigation using the radio direction finding (RDF) technique. RDF can determine

4104-539: The GPO testing team's observation that aircraft flying near the receiver caused the signal to change in intensity, an annoying effect known as fading . The stage was now set for the development of radar in the UK. Using Wilkins' knowledge that shortwave signals bounced off aircraft, a BBC transmitter to light up the sky as in Appleton's experiment, and Watt's RDF technique to measure angles, a complete radar could be built. While such

4212-650: The Met Office and NPL, were combined to form the Radio Research Station (with the same acronym, RRS), run by the NPL with Watt as the Superintendent. This provided Watt with direct contact to the research community, as well as the chief signals officers of the British Army , Royal Navy and Royal Air Force . Watt became a well-known expert in the field of radio technology. This began a long period where Watt agitated for

4320-609: The Met Office located many of its observation and data collection points on RAF airfields , and this accounts for the large number of military airfields mentioned in weather reports even today. In 1936 the Met Office split with services to the Royal Navy being provided by its own forecasting services. It became an executive agency of the Ministry of Defence in April 1990, a quasi-governmental role, being required to act commercially. Following

4428-477: The NPL to take a more active role in technology development, as opposed to its pure research role. Watt was particularly interested in the use of radio for long-range aircraft navigation, but the NPL management at Teddington was not receptive and these proposals went nowhere. In 1931, Arnold Frederic Wilkins joined Watt's staff in Slough. As the "new boy", he was given a variety of menial tasks to complete. One of these

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4536-514: The RAF carried out large-scale exercises with up to 350 aircraft. The forces were split, with bombers attempting to attack London, while fighters, guided by the Observer Corps , attempted to stop them. The results were dismal. In most cases, the vast majority of the bombers reached their target without ever seeing a fighter. To address the one-sided results, the RAF gave increasingly accurate information to

4644-450: The RAF. In September 2003 the Met Office moved its headquarters from Bracknell in Berkshire to a purpose-built £80m structure at Exeter Business Park, near junction 29 of the M5 motorway . The new building was officially opened on 21 June 2004 – a few weeks short of the Met Office's 150th anniversary – by Robert May, Baron May of Oxford . It has a worldwide presence – including

4752-480: The RRS team, along with Rowe representing the Tizard Committee. Watt was so impressed he later claimed to have exclaimed: "Britain has become an island again!" Rowe and Dowding were equally impressed. It was at this point that Watt's previous agitation over development became important; NPL management remained uninterested in practical development of the concept, and was happy to allow the Air Ministry to take over

4860-454: The RRS. The system consisted of several parallel dipoles separated vertically on the receiver masts. Normally the RDF goniometer was connected to two crossed dipoles at the same height and used to determine the bearing to a target return. For height finding, the operator instead connected two antennas at different heights and carried out the same basic operation to determine the vertical angle. Because

4968-433: The Tizard Committee on 28 January 1935. The utility of the concept was evident to all attending, but the question remained whether it was actually possible. Albert Rowe and Wimperis both checked the maths and it appeared to be correct. They immediately wrote back asking for a more detailed consideration. Watt and Wilkins followed up with a 14 February secret memo entitled Detection and Location of Aircraft by Radio Means . In

5076-538: The Treasury for another £10,000. Dowding was extremely impressed with the concept, but demanded a practical demonstration before further funding was released. Wilkins suggested using the new 10 kW, 49.8 m BBC Borough Hill shortwave station in Daventry , Northamptonshire as a suitable ad hoc transmitter. The receiver and an oscilloscope were placed in a delivery van the RRS used for measuring radio reception around

5184-639: The UK and abroad (including frontline units in conflict zones). Royal Navy weather forecasts are generally provided by naval officers, not Met Office personnel. The Shipping Forecast is produced by the Met Office and broadcast on BBC Radio 4 , for those traversing the seas around the British Isles . The Met Office issues Severe Weather Warnings for the United Kingdom through the National Severe Weather Warning Service (NSWWS). These warn of weather events that may affect transport infrastructure and endanger people's lives. In March 2008,

5292-542: The UK and surroundings (replacing the 4 km model), 48-hour forecasts from the 12 km resolution NAE model covering Europe and the North Atlantic, and 144-hour forecasts from the 25 km resolution global model (replacing the 40 km global model). The Met Office's Global Model forecast has consistently been in the top 3 for global weather forecast performance (in the decades up to 2010) in independent verification to WMO standards. Products for other regions of

5400-483: The UK open to attack by Germany's ever-growing air fleet. Conversely, if the UK had such a device, the population could be protected. In 1934, along with a movement to establish a scientific committee to examine these new types of weapons, the RAF offered a £1,000 prize to anyone who could demonstrate a working model of a death ray that could kill a sheep at 100 yards; it went unclaimed. The need to research better forms of air defense prompted Harry Wimperis to press for

5508-464: The UK, US, Japan, Germany and others had all considered this concept and put at least some amount of effort into developing it. Lacking ranging information, such systems remained of limited use in practical terms; two angle measurements could be used, but these took time to complete using existing RDF equipment and the rapid movement of the aircraft during the measurement would make coordination difficult. Since 1915, Robert Watson-Watt had been working for

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5616-604: The ability to process the complex return signal was simply not possible at the time. To counter the threat of Soviet bombers flying over the Arctic, the U.S. and Canada developed the DEW Line . Other examples ( Pinetree Line ) have since been built with even better performance. An alternative early warning design was the Mid-Canada Line , which provided "line breaking" indication across the middle of Canada , with no provision to identify

5724-424: The active volcanoes in its area of responsibility. The NAME dispersion model developed by the Met Office is used to forecast the movement of the ash clouds 6, 12 and 18 hours from the time of the alert at different flight levels. The Met Office issues air quality forecasts made using NAME , the Met Office's medium-to-long-range atmospheric dispersion model . It was developed as a nuclear accident model following

5832-427: The air, and therefore improves their performance in the long-range role where their coverage area will often include precipitation. This also has the side-effect of lowering their optical resolution , but this is not important in this role. Likewise, EW radars often use much lower pulse repetition frequency to maximize their range, at the cost of signal strength, and offset this with long pulse widths , which increases

5940-475: The bearing to a radio transmitter, and several such measurements can be combined to produce a radio fix , allowing the receiver's position to be calculated. Given some basic changes to the broadcast signal, it was possible for the receiver to determine its location using a single station. The UK pioneered one such service in the form of the Orfordness Beacon . Through the early period of radio development it

6048-404: The bearing to the target, not the range, and due to the low power of radio equipment of that era, they were useful only for short-range detection. This led to their use for iceberg and collision warning in fog or bad weather, where all that was required was the rough bearing of nearby objects. The use of radio detection specifically against aircraft was first considered in the early 1930s. Teams in

6156-498: The changing wavelengths. The application of this technique to a detection system was not lost on those working in the field, and such a system was prototyped by W. A. S. Butement and P. E. Pollard of the British Signals Experimental Establishment (SEE) in 1931. The War Office proved uninterested in the concept and the development remained little known outside SEE. At the same time, the need for such

6264-540: The corporation's legal obligation to provide best value for money for the licence fee payers. The BBC still uses some Met Office data for certain forecasts, particularly severe weather warnings and the Shipping Forecast. The Met Office is one of only two World Area Forecast Centres or WAFCs, and is referred to as WAFC London. The other WAFC is located in Kansas City, Missouri , and known as WAFC Washington. WAFC data

6372-475: The countryside. On 26 February 1935, they parked the van in a field near Upper Stowe and connected it to wire antennas stretched across the field on top of wooden poles. A Handley Page Heyford made four passes over the area, producing clearly notable effects on the CRT display on three of the passes. A memorial stone was placed at the site of the test. Observing the test were Watt, Wilkins, and several other members of

6480-413: The death ray is not possible, how can we help them?" Wilkins recalled the earlier report from the GPO, and noted that the wingspan of a contemporary bomber aircraft , about 25 m (82 ft), would be just right to form a half-wavelength dipole antenna for signals in the range of 50 m wavelength, or about 6 MHz. In theory, this would efficiently reflect the signal and could be picked up by

6588-429: The defenders, eventually telling the observers where and when the attacks would be taking place. Even then, 70 per cent of the bombers reached their targets unhindered. The numbers suggested any targets in the city would be destroyed. Squadron Leader P. R. Burchall summed up the results by noting that "a feeling of defencelessness and dismay, or at all events of uneasiness, has seized the public." In November, Churchill gave

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6696-453: The development of an observational network which could then be used to provide synoptic analysis. The Met Office started in 1861 to provide weather forecasts to newspapers. FitzRoy requested the daily traces of the photo- barograph at Kew Observatory (invented by Francis Ronalds ) to assist in this task and similar barographs and as well as instruments to continuously record other meteorological parameters were later provided to stations across

6804-693: The director. Wilkins followed him to the DCD, and A. P. Rowe took over AMES at Bawdsey. In August 1938, the first five stations were declared operational and entered service during the Munich crisis , starting full-time operation in September. Early-warning radar EW radars tend to share a number of design features that improve their performance in the role. For instance, EW radar typically operates at lower frequencies, and thus longer wavelengths, than other types. This greatly reduces their interaction with rain and snow in

6912-519: The enemy." Even the highest levels of the RAF came to agree with this policy, publicly stating that their tests suggested that "'The best form of defence is attack' may be all-too-familiar platitudes, but they illustrate the only sound method of defending this country from air invasion. It is attack that counts." As it became clear the Germans were rapidly rearming the Luftwaffe , the fear grew RAF could not meet

7020-455: The engine to stall. One commonly repeated story involved an English couple who were driving in the Black Forest on holiday and had their car fail in the countryside. They claimed they were approached by soldiers who told them to wait while they conducted a test, and were then able to start their engine without trouble when the test was complete. This was followed shortly thereafter by a story in

7128-466: The expected reflectivity of an aircraft. The received signal would be only 10 times as strong as the transmitted one, but such sensitivity was considered to be within the state of the art. To reach this goal, a further improvement in receiver sensitivity of two times was assumed. Their ionospheric systems broadcast only about 1 kW, but commercial shortwave systems were available with 15 amp transmitters (about 10 kW) that they calculated would produce

7236-463: The face of such a threat is inexcusable until it has definitely been shown that all the resources of science and invention have been exhausted." In 1923–24 inventor Harry Grindell Matthews repeatedly claimed to have built a device that projected energy over long ranges and attempted to sell it to the War Office, but it was deemed to be fraudulent. His attempts spurred on many other inventors to contact

7344-574: The formation of a study group to consider new concepts. Lord Londonderry , then Secretary of State for Air , approved the formation of the Committee for the Scientific Survey of Air Defence in November 1934, asking Henry Tizard to chair the group, which thus became better known to history as the Tizard Committee . When Wimperis sought an expert in radio to help judge the death-ray concept, he

7452-445: The globe are sold to customers abroad, provided for MOD operations abroad or provided free to developing countries in Africa. If necessary, forecasters may make adjustments to the computer forecasts. Data is stored in the Met Office's own PP-format . Formed in 2009, the Flood Forecasting Centre (FFC) is a joint venture between the Environment Agency and the Met Office to provide flood risk guidance for England and Wales. The Centre

7560-424: The information to the fighter aircraft led to the first integrated ground-controlled interception network, the Dowding system . By the time the war started, most of the east and south coasts had radar coverage. Chain Home proved important during the Battle of Britain in 1940. CH systems could detect enemy aircraft while they were forming over France, giving RAF commanders ample time to marshal their aircraft in

7668-420: The military through its front line offices at RAF and Army bases both in the UK and overseas and its involvement in the Joint Operations Meteorology and Oceanography Centre (JOMOC) with the Royal Navy. The Mobile Met Unit (MMU) are a unit consisting of Met Office staff who are also RAF reservists who accompany forward units in times of conflict advising the armed forces of the conditions for battle, particularly

7776-404: The new memo, Watson-Watt and Wilkins first considered various natural emanations from the aircraft – light, heat and radio waves from the engine ignition system – and demonstrated that these were too easy for the enemy to mask to a level that would be undetectable at reasonable ranges. They concluded that radio waves from their own transmitter would be needed. Wilkins gave specific calculations for

7884-455: The new system recently completed at Bawdsey failed. The next day, Robert Hanbury-Brown and the new recruit Gerald Touch started up the Orfordness system and were able to run the demonstrations from there. The Orfordness site was not closed until 1937. The system was deliberately developed using existing commercially available technology to speed introduction. The development team could not afford

7992-454: The objective of winning such a tit-for-tat exchange and many suggested they invest in a massive bomber building exercise. Others felt advances in fighters meant the bomber was increasingly vulnerable and suggested at least exploring a defensive approach. Among the latter group was Lindemann, test pilot and scientist, who noted in The Times in August 1934 that "To adopt a defeatist attitude in

8100-588: The observing network. Publication of forecasts ceased in May 1866 after FitzRoy's death but recommenced in April 1879. Following the First World War , the Met Office became part of the Air Ministry in 1919, the weather observed from the top of Adastral House (where the Air Ministry was based) giving rise to the phrase "The weather on the Air Ministry roof". As a result of the need for weather information for aviation,

8208-416: The other experiments at the RRS at Slough, and expressing their gratitude that the Air Ministry had granted them access to unused land at Orfordness to continue their efforts. Bowen continued increasing the voltage in the transmitter, starting with the 5000  volt maximum suggested by the Navy, but increasing in steps over several months to 12,000 V, which produced pulses of 200 kW. Arcing between

8316-459: The other members' complaints about his behaviour were ignored. The matter was eventually referred back to Lord Swinton , the new Secretary of State for Air. Swinton solved the problem by dissolving the original Committee and reforming it with Appleton in Lindemann's place. As the development effort grew, Watt requested a central research station be established "of large size and with ground space for

8424-428: The path of the raid. This had the effect of multiplying the effectiveness of the RAF to the point that it was as if they had three times as many fighters, allowing them to defeat frequently larger German forces. The Chain Home network was continually expanded, with over 40 stations operational by the war's end, including mobile versions for use overseas. Late in the war, when the threat of Luftwaffe bombing had ended,

8532-402: The range was continually pushed out. During a 24 July test, the receiver detected a target at 40 mi (64 km) and the signal was strong enough that they could determine the target was actually three aircraft in close formation. By September the range was consistently 40 miles, increasing to 80 miles (130 km) by the end of the year, and with the power improvements Bowen worked into

8640-422: The shorter wavelength produced no loss of performance. This led to a further reduction to 13 m, and finally the ability to tune between 10 and 13 m, (roughly 30-20 MHz) to provide some frequency agility to help avoid jamming. Wilkins' method of height-finding was added in 1937. He had originally developed this system as a way to measure the vertical angle of transatlantic broadcasts while working at

8748-459: The signal at the cost of lowering range resolution. The canonical EW radar is the British Chain Home system, which entered full-time service in 1938. It used a very low pulse repetition of 25 pps and very powerful transmissions (for the era) reaching 1 MW in late-war upgrades. The German Freya and US CXAM (Navy) and SCR-270 (Army) were similar. Post-war models moved to the microwave range in ever-increasingly powerful models that reached

8856-406: The south and disappear. Watt phoned the nearby Seaplane Experimental Station at Felixstowe and the superintendent stated that a Supermarine Scapa flying boat had just landed. Watt requested the aircraft return to make more passes. This event is considered the official birth date of radar in the UK. Aircraft from RAF Martlesham Heath took over the job of providing targets for the system, and

8964-480: The system was improved and a new stage of warning was introduced, the 'Advisory'. The Met Office along with Irish counterpart Met Éireann introduced a storm naming system in September 2015 to provide a single authoritative naming system for the storms that affect the UK and Ireland. The first named storm under this system, Abigail was announced on 10 November 2015. In 2019, the Met Office and Met Éireann were joined by Dutch national weather forecasting service

9072-401: The target's exact location or direction of travel. Starting in the 1950s, a number of over-the-horizon radars were developed that greatly extended detection ranges, generally by bouncing the signal off the ionosphere . Today the early warning role has been supplanted to a large degree by airborne early warning platforms. By placing the radar on an aircraft, the line-of-sight to the horizon

9180-561: The team's progress. Watt secretly arranged for a Vickers Valentia to fly nearby, and years later insisted that he saw the echoes on the display, but no one else recalls seeing these. Watt decided not to return to the RRS with the rest of the Tizard group and stayed with the team for another day. With no changes made to the equipment, on 17 June the system was turned on and immediately provided returns from an object at 17 mi (27 km). After tracking it for some time, they watched it fly off to

9288-404: The team. Days later, the Treasury released £12,300 for further development, and a small team of the RRS researchers were sworn to secrecy and began developing the concept. A system was to be built at the RRS station, and then moved to Orfordness for over-water testing. Wilkins would develop the receiver based on the GPO units, along with suitable antenna systems. This left the problem of developing

9396-684: The time to develop and debug new technology. Watt, a pragmatic engineer, believed "third-best" would do if "second-best" would not be available in time and "best" never available at all. This led to the use of the 50 m wavelength (around 6 MHz), which Wilkins suggested would resonate in a bomber's wings and improve the signal. Unfortunately, this also meant that the system was increasingly blanketed by noise as new commercial broadcasts began taking up this formerly high-frequency spectrum . The team responded by reducing their own wavelength to 26 m (around 11 MHz) to get clear spectrum. To everyone's delight, and contrary to Wilkins' 1935 calculations,

9504-436: The transmitter antenna was a single dipole strung horizontally between two 75 foot (23 m) poles, and the receiver a similar arrangement of two crossed wires. The system showed little success against aircraft, although echoes from the ionosphere as far as 1,000 miles away were noted. The group released several reports on these effects as a cover story , claiming that their ionospheric studies had been interfering with

9612-399: The transmitter antenna was deliberately focused vertically to improve gain, a single pair of such antennas would only cover a thin vertical angle. A series of such antennas was used, each pair with a different center angle, providing continuous coverage from about 2.5 degrees over the horizon to as much as 40 degrees above it. With this addition, the final remaining piece of Watt's original memo

9720-401: The transmitter, was over 100 mi (160 km) by early 1936. In August 1935, Albert Rowe , secretary of the Tizard Committee, coined the term "Radio Direction and Finding" (RDF), deliberately choosing a name that could be confused with "Radio Direction Finding", a term already in widespread use. In a 9 September 1935 memo, Watson-Watt outlined the progress to date. At that time the range

9828-602: The two stations. The missing technique that made radar practical was the use of pulses to determine range by measuring the time between the transmission of the signal and reception of the reflected signal. This would allow a single station to measure angle and range simultaneously. In 1924, two researchers at the Naval Research Laboratory in the United States, Merle Tuve and Gregory Briet, decided to recreate Appleton's experiment using timed pulsed signals instead of

9936-463: The utility of RDF was Lindemann. He had been placed on the Committee at the insistence of his friend, Churchill, and proved unimpressed with the team's work. When he visited the site, he was upset by the crude conditions, and apparently, by the box lunch he had to eat. Lindemann strongly advocated the use of infrared systems for detection and tracking and numerous observers have noted Lindemann's continual interference with radar. As Bowen put it, Within

10044-428: The valves required the transmitter to be rebuilt with more room between them, while arcing on the antenna was solved by hanging copper balls from the dipole to reduce corona discharge . By June the system was working well, although Bainbridge-Bell proved to be so skeptical of success that Watt eventually returned him to the RRS and replaced him with Nick Carter. The Tizard Committee visited the site on 15 June to examine

10152-426: The weather that may affect aviation operations. Some stations report only CLIMAT data (e.g. maximum and minimum temperatures, rainfall totals over a period, etc.) and these are usually recorded at 0900 and 2100 hours daily. Weather reports are often performed by observers not specifically employed by the Met Office, such as Air traffic control staff, coastguards, university staff and so on. Meteorological Research

10260-404: Was about 40 mi (64 km), so Watson-Watt suggested building a complete network of stations 20 mi (32 km) apart along the entire east coast. Since the transmitters and receivers were separate, to save development costs he suggested placing a transmitter at every other station. The transmitter signal could be used by a receiver at that site as well as the ones on each side of it. This

10368-479: Was accomplished and the system was ready to go into production. Industry partners were canvassed in early 1937, and a production network was organized covering many companies. Metropolitan-Vickers took over design and production of the transmitters, AC Cossor did the same for the receivers, the Radio Transmission Equipment Company worked on the goniometers, and the antennas were designed by

10476-524: Was carried out at RAE Bedford with instruments being carried by barrage balloons until the RAE facility closed in the 1980s. The Met Office association with Cardington continues by maintaining a Meteorological Research Unit (MRU). This is responsible for conducting research into part of the atmosphere called the boundary layer by using a tethered balloon which is kept in a small portable hangar. The Facility for Airborne Atmospheric Measurements (FAAM), part of

10584-638: Was carrying out experiments that would lead to him winning the Nobel Prize in Physics . Using a BBC transmitter set up in 1923 in Bournemouth and listening for its signal with a receiver at Oxford University , he was able to use changes in wavelength to measure the distance to a reflective layer in the atmosphere then known as the Heaviside layer . After the initial experiments at Oxford, an NPL transmitter at Teddington

10692-423: Was completed by the end of the year, with detection ranges on the order of 100 mi (160 km). In 1936 attention was focused on a production version, and early 1937 saw the addition of height finding. The first five stations, covering the approaches to London, were installed by 1937 and began full-time operation in 1938. Over the next two years, additional stations were built while the problem of disseminating

10800-681: Was established on 1 August 1854 as a small department within the Board of Trade under Vice Admiral Robert FitzRoy as a service to mariners . The loss of the passenger vessel, the Royal Charter , and 459 lives off the coast of Anglesey in a violent storm in October 1859 led to the first gale warning service. FitzRoy established a network of 15 coastal stations from which visual gale warnings could be provided for ships at sea. The new electric telegraph enabled rapid dissemination of warnings and also led to

10908-432: Was naturally directed to Watt. He wrote to Watt "on the practicability of proposals of the type colloquially called 'death ray'". The two met on 18 January 1935, and Watt promised to look into the matter. Watt turned to Wilkins for help but wanted to keep the underlying question a secret. He asked Wilkins to calculate what sort of radio energy would be needed to raise the temperature of 8 imperial pints (4.5 L) of water at

11016-410: Was quickly rendered moot by the rapid increases in range. When the Committee next visited the site in October, the range was up to 80 mi (130 km), and Wilkins was working on a method for height finding using multiple antennas. In spite of its ad hoc nature and short development time of less than six months, the Orfordness system had already become a useful and practical system. In comparison,

11124-560: Was the first climate and weather forecast provider to be recognised as a Global Producing Centre of long range forecasts by the World Meteorological Organisation and continues to provide forecasts to the WMO for dissemination to other national meteorological services worldwide. Met Office research has broken new ground in seasonal forecasting for the extratropics and has demonstrated its abilities in its seasonal predictions of

11232-478: Was the first early warning radar network in the world and the first military radar system to reach operational status. Its effect on the war made it one of the most powerful systems of what became known as the "Wizard War". In late 1934, the Tizard Committee asked radio expert Robert Watson-Watt to comment on the repeated claims of radio death rays and reports suggesting Germany had built some sort of radio weapon. His assistant, Arnold Wilkins , demonstrated that

11340-520: Was to select a new shortwave receiver for ionospheric studies, a task he undertook with great seriousness. After reading everything available on several units, he selected a model from the General Post Office (GPO) that worked at (for that time) very high frequencies. As part of their tests of this system, in June 1932 the GPO published a report, No. 232 Interference by Aeroplanes . The report recounted

11448-552: Was unusual in that area. The large manor house on the property would have ample room for experimental labs and offices. In February and March 1936, the team moved to Bawdsey Manor and established the Air Ministry Experimental Station (AMES). When the scientific team left in 1939, the site became the operational CH site RAF Bawdsey . While the "ness team" began moving to Bawdsey, the Orfordness site remained in use. This proved useful during one demonstration when

11556-452: Was used as a source, received by Appleton in an out-station of King's College in the East End of London. Watt learned of these experiments and began conducting the same measurements using his team's receivers in Slough. From then on, the two teams interacted regularly and Watt coined the term ionosphere to describe the multiple atmospheric layers they discovered. In 1927 the two radio labs, at

11664-428: Was widely known that certain materials, especially metal, reflected radio signals. This led to the possibility of determining the location of objects by broadcasting a signal and then using RDF to measure the bearing of any reflections. Such a system saw patents issued to Germany's Christian Hülsmeyer in 1904, and widespread experimentation with the basic concept was carried out from then on. These systems revealed only

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