the party's ruling body. two men — believed to have been members of the islamic state cell known as "the beatles" — complain they can't have a fair trial because the government has stripped them of their british citizenship. russia has more than doubled the number of british diplomats it plans to expel, because of the blame being placed on moscow over the salisbury nerve agent attack. a private funeral service has taken place in cambridge for stephen hawking. the astronomer royal, lord rees and actor eddie redmayne gave readings at the service now on bbc news, the weather world team discover how meteorology has helped to shape the royal air force. this time on weather world we're marking 100 years of the royal air force. and where better than here at its biggest base, raf brize norton? nick and i have been finding out about how ground operations work

with air traffic control in times of severe weather to keep this crucial airbase operational. and i'll be at raf marham in norfolk, sharing some of my experiences of being an operational forecaster at an raf base. also on weather world, crippling cold, uk and much of europe falls victim to the beast from the east. freak freeze... the flood that turned to ice. how a weather disaster can strike as if from nowhere. the storms that can sweep you off your feet. but some people try to carry on regardless! this year marks the centenary of britain's royal air force, the raf.

we've come to its largest station at raf brize norton in oxfordshire, home to almost 6,000 service personnel. the aircraft based here support british military operations around the globe, it's surprisingly busy with frequent landings, departures and training manoeuvres. a lot of what happens in a military airport like this is very different from a commercial airport but some things are the same. air traffic control is the hub of all activity and that is where sarah is now. i'm here with simon, who is in charge of all air traffic control here and tell me, why is it so important brize norton stays open all year round? it is home to the raf strategic and tactical air transport fleet. we're also the gateway to operations across the world.

that's to say delivering, whether it's troops, cargo or disaster relief, as we saw at the end of 2017 in the caribbean. meteorology and aviation will always be intrinsically linked, so how do you get your weather information here? we're very lucky insofar as we have our own met office, they pass the weather information across to here in traffic control via fax, would you believe, this is translated into our local systems for reference by controllers. so you get this fax with coded weather information, and how is the weather looking out there today? it's looking pretty good out there at the moment, the met office are forecasting 30 kilometres with no weather phenomena, a cloud base of 2,800 feet and positive temperatures plus 11. how important is it that at the operations you get a detailed weather forecast? it is important that we know what the weather is doing, and vital that we pass accurate information on to pilots transiting through.

it's notjust pilots that need to be prepared, but we all need to be ready for whatever the weather throws at us. bitterly cold weather over the past few days coming from siberia, the beast from the east as it's been called... are you ready for the beast from the east? weather is set to be colder than the arctic? spring on hold, early march, a winter biteback brings much of the uk to a standstill in the coldest, snowiest weather since 2010. my god! in scotland, some traffic keeps moving... but only just. in wales, the snow blows into drifts so deep, they bury cars. bitterly cold siberian air with severe wind chill

and widespread snow puts britain in much of a freeze. and produces the coldest march day on record. traction to pull the car through. what are you going to do? go home and have a cup of tea. that's the answer to everything, isn't it? some railway lines were overwhelmed too. this driver's eye view shows what, for now, is the end of the line. so what caused the so—called beast from the east? the answer can be found in the stratosphere, high above the arctic, where the normal flow of air weakened, allowing air to descend and warm by as much as 50 degrees. this is sudden stratospheric warming. but it also impacts the jet stream, reversing it from its usual westerly to an easterly flow, resulting in bitterly cold air from siberia carrying across much of europe.

few places escaped. in italy, rome gets its biggest snowfall in decades, covering the city's landmarks. cue a mass snowball fight in st peter's square next to the vatican, even priestsjoined in! but even before the beast from the east, winter in europe had produced some snowy surprises. this is moscow in february, after its heaviest one—day snowfall on record. 38 centimetres, more than half what the city would normally get in a whole month. in january, unusually heavy snowfall hits parts of africa too — this is morocco. the snow even reached the edge of the sahara desert in algeria. it does get cold here, but there is rarely enough moisture for any precipitation! winter whiteout in iran,

as the capital tehran is blanketed with heavy snow in january, much welcome moisture here offering some brief drought relief. can you believe this is tallahassee, florida ? and we are getting snow...? no, we can't, but it is, and injanuary it's the first measurable snow here in nearly three decades. more familiar territory for a winter storm, the north—east usa, several of them in march and this one gave the city of boston its snowiest march day on record. this storm that struck at the start of the year was dubbed a bomb cyclone, hitting boston with notjust wind, not just snow, but a three foot flooding storm surge. then this. after the flood, the big freeze, and astonishing scenes as frozen floodwater entombs cars in ice. back to the beast from the east.

this video shows the huge effort at raf brize norton to keep the runway open in the face of prolonged snowfall, blowing around and drifting in the wind. as some commercial airports succumb to the severe weather, closing the crucial runway here is never an option. sergeant natasha watkins, you were here on duty during and before the beast from the east, when did you first hear it was coming? so, the met office that we have based here gave us a warning on tuesday, the beast from the east was coming on the thursday. so we spent some time checking our manpower, checking the operational aircraft, which priority they would take, making sure our equipment was ready. kind of all the things that you plan for without it actually happening. it must have been an amazing few days. it was, yeah. you're laughing about it, this was an experience. it was, incredible.

why was it so valuable to your teams, going through that and dealing with all of that cold and snow? so, they carry out training prior to the start of every season and it's a dry run. you don't really get to use it in anger until something like the beast from the east comes in. do you actually like snow yourself? everybody says i'm a hot weather person, but i really like it. i like it when i'm operational rather than being out in it myself. this is one of the ploughs that was operational. sarah is up in the cab. that's right. i've got prime position, and there is a fleet of eight of these vehicles here at brize norton. i'm with pete, one of the men involved in keeping the airfield open in all types of weather, so, pete, it's been quite a busy winter for you? really busy this year. when the beast from the east affected us, we had these vehicles out for 56 hours, constantly, up and down the runway, maintaining it, keeping it open.

you can control all the elements of the vehicle from the cab? yeah, this computer controls the snow plough at the front, the brushes in the middle, and the blowers at the back. shall we hop out and you can show me? great. we saw how it is controlled in the cab, talk me through the equipment down here on the ground, starting at the front. the plough at the front, the idea is it pushes the snow out of the way, so we push it in the direction of the wind, we push it to the left or the right. further down, what's the next? the brushes brush the snow, so what's left after the snow ploughs brush the snow away, there will be a layer of snow, so the brushes break it up, they also push it in the same direction as the snowplough, at the back, the blowers, it blows all the excess liquid or slush away from the airfield again in the same direction.

thank you so much for explaining all that. now, a little bit later we'll be talking to air traffic control to see how their teams work with this team to deal with the beast from the east. 20 years ago i began my weather career on an raf base and i got to forecast for an aircraft like the tornado. i've come here to raf marham to find out how the rules of meteorology have changed. i've come inside to the met office at raf marham, the forecasters are watching the weather, making the documents, much like i used to do when i started to weather forecast. and it's all for people such as this, squadron leaderjim furness, who has over 3,000 hours of flying under his belt with the tornados. we were at cranwell at the same time. we were learning to fly. right from the start, meteorology forms a big part of the flying training? it's a key, basic skill, every aviator learns during basic training.

when we were back at cranwell in the day, the forecast was generally the same, delivered on acetate slides, whereas now, technology has moved forward now it's delivered through computers but fundamentally it's still the same sort of forecast, delivering a concise, clear picture to aviators of what weather conditions they can expect during their training or flight. you have flown the tornado and lancaster, how has the situation changed as far as using the weather forecast? the lancaster is a precious aircraft, one of two flying in the world, and we need to make sure we don't expose it to any adverse weather conditions. it doesn't have equipment on board to help us actively read the weather in the way the tornado can, so we have to be very careful about the conditions we expose it to. i remember eyeballing the pilots, there was always a bit more pressure to forecast for the lancaster. we'll come back to you later, we'll look at different ways the weather is being tackled, join us later in the programme, to see the novel ways the raf used to tackle fog,

especially during the second world war. now some of your pictures. few places escape the snow which blanketed large parts of the british isles, the situation made worse as it was blown into drifts by the bitterly cold easterly wind. but it wasn't just snow, there was also freezing rain. this is when supercooled raindrops freeze instantly to anything they touch — the result, a layer of glazed ice which makes for some of the most beautiful, but hazardous winter weather there is. you can become a bbc weather watcher by signing up online. still to come, fighting fog — how the raf cleared the air to keep flying. plus, we look at how technology in the tornado has radically improved landing conditions in the raf. we are back at raf brize norton,

and we saw earlier all the work that was done to keep this important military airport opened during the cold spell, the so—called beast from the east. but how do they know whether the runway is safe to take off or land on? well, this is such an important piece of kit, it's called a mu meter and corporal natalie adams is with me to tell me what it does. what does it do? it's designed to test the friction on the runway. we'll get the laptop readings. how does it work? we'll put the wheel down on the back... there it goes. and that's fed through wires into the vehicle through to the laptop. that's how we will get the readings. clearly nothing wrong with the friction on the runway today, but we're going to give it a training run, let's get in and see it in action.

natalie, time to put the mu—meter through its paces, we're on a taxiway, sean is driving us, head off when you are ready. here we go. what is going to happen now? we're going to test the friction of the runway, using the mu—meter. we're currently getting up to 40mph as quickly as possible. we'll have to stay at a steady pace to make sure we get the correct readings. accurate readings. the wheel is down. yes, that's where we get the readings from. we're ready for a a0 miles an hour emergency stop, sean, whenever you're ready... yes! i felt that, safely done though. we have done the start, what are you looking for in terms of readings? we'll get readings, and 0.7 is a good reading, anything below that means the friction on the runway isn't very good, and then we would have to look at why, is it ice, do we need to start de—icing? that's some weather science

from here at the surface. now, sarah has some more from a long way up in the sky. you'll often hear meteorologists talking about the jet stream, but what is it? how are they important? a jet stream is a fast—moving, narrow ribbon of air, high up in the atmosphere, about six miles above our heads. jet streams are formed at the boundary of two air masses, so for instance in the north atlantic, cold polar air meets much milder subtropical air. here, jet streams typically flow from west to east, down to the easterly rotation of the earth and the resulting coriolis effect, jet streams can be thousands of miles long, and can travel at speeds of more than 200 miles an hour, so they have a dramatic affect on air travel, depending whether you are travelling with or against the jet stream, flight times and fuel consumption can be dramatically affected. and what about the weather? well, jet streams don't always

flow in a straight line, we see ripples and buckles in the streams and quite small—scale ripples can lead to rapidly deepening depressions and big meanders mean some areas can see successful weather systems, whereas other parts of the world can see quieter weather with a blocking area of high pressure. so observing and predicting the behaviour of jet streams is the most vital tool for a weather forecaster. a strong jet stream drove some powerful atlantic weather systems into europe injanuary. the driver of this car braved a flooded seafront road in ireland as storm eleanor arrived with winds of up to 100 miles an hour. another storm roared across northern europe later in january, literally blowing people off their feet in the netherlands. many were caught off—guard, despite the highest level of weather warning for wind. this roof was no match for some of the most powerful winds ever recorded here.

the storm killed several people in the netherlands and germany. in the french capital, paris, weeks of heavy rain sent the river seine soaring again — it was the wettest december and january here in 50 years. mudslides surged through neighbourhoods in the usa — this is southern california in january. torrential rains poured on ground scorched and cleared of vegetation by the state's largest wildfire in history, the mud had nowhere to go and nothing to hold it back. more than 20 people were killed in the devastation that followed. tropical cyclones have continued to roam the pacific. in february, tonga is in the firing line of cyclone giza, the worst to hit the country since modern weather records began 60 years ago. among the casualties and the widespread destruction, the more than century—old parliament building.

in australia injanuary, it's near record summer heat that's making the headlines as temperatures in sydney top 47 celsius. and in south africa, unprecedented drought takes cape town closer to becoming the world's first major city to run out of water. every day without rain takes the 4 million people who live here closer to the day the taps run dry. brazil in february, and the eerie sight of a forest trail completely submerged by water. the flood subsided almost as quickly as it came but it produced scenes that look like they come from another world. newsreel: continuous lines of petrol burners are a vital feature of fog investigation dispersal operations or in raf parlance, operation fido. 0ver100 years of raf operations, how they tackled the weather

elements in the raf has changed, and today we could never imagine this but during the second world war the problem of fog was met by this unusual solution, fido. the public should know that fido, in this war, has saved over 10,000 aircrew lives. moreover, fido has made it possible to carry out operations in base weather which would have stopped all flying in the past. first operational use of fido was in november 1943. .. when low—lying fog made it unsafe for aircraft to land, they would be diverted to fido—enabled air fields, where gas filled pipelines running alongside the base will be set ablaze, the heat burning away the fog, giving pilots clear sight of the runways. that system contained 500,000 gallons of petrol when full, costing thousands every time it was deployed. such costly methods would never

be used these days. at the base we have an infra—red camera... as the squadron leader explains, aviation technology in planes such as the tornado has really moved on. tornado is designed as an all—weather capable aircraft and to help us fly at low altitude we have a terrain falling radar housed in the nose, and that will scan in front of the aircraft, reading the terrain, and combining with the autopilot it will allow the aircraft to fly at low altitude at any height we desire in any weather imaginable. so, technology may have changed but we've got the same problems, how to land and get back to base, how do you deal with fog? a couple of ways, we can either use assistance from the ground, air—traffic control, a precision approach radar, where they will talk you back down, and we've also got instrument landing system, which is common across multiple types of aircraft, whereby the pilot follows steering commands, to guide himself back down to the runway.

the final option with this is when we combine radar, my skills as a radar operator from the back—seat, pilots and flying skills. if we can't see the ground or the runway by a set height, about 200ft, at that point we're going to go around and we're going to fly off to our diversion. squadron leader, thank you. it's going to be a dull and wet start to the day... it's notjust how we deal with the weather that has changed over the years but also how it looks on our tv screens, computers and mobile phones. bbc weather's appearance has come a long way since the first television forecast more than 60 years ago. so, that's the picture this morning. watch out for ice first thing this morning, too... around the moray firth... and in february, another new look was unveiled. simon hunt is our creative director — talk us through what viewers can expect to see with new graphics. they will notice the map looks different, it's high—resolution, it's green, go in closer, and you can see high—resolution data for the weather.

we have the ability to show a 3—d globe with weather on it which the presenters can move around quite easily to create the editorial story they want to tell. we were looking beyond the clouds at the end of january, as parts of the world marvelled at an extremely rare celestial event, a super blue blood moon. "super" because it was a full moon, when the moon is at its closest to the earth, making it appear larger than usual — "blue" because of the second full moon of the month, that's where the phrase for a very infrequent event, "once in a blue moon" comes from, and "blood" when the moon's reddish colour during a total lunar eclipse. it's the first time these elements have combined since 1866. not quite as rare but it's still six years since people have been able to do this, skate on amsterdam's frozen canals. and finally, another snowstorm in boston, usa,

and this is a man dressed as elsa from the disney film frozen, pushing a police truck. oh, just let it go! # the cold never bothered me anyway... and that's it from us. you can find clips of previous episodes on the website. we will be back later in the year, until then, keep checking the forecast! hello there, conditions have been

improving through the day. it has been turning drierfor improving through the day. it has been turning drier for many. improving through the day. it has been turning drierfor many. the rain reserved for the east. still wintry over the higher ground. many places have seen scenes like this a lot of cloud around, quite cool as well. but there have been some holes in the cloud. some of the best of the sunshine was across the north—west of scotland. we have this high pressure toppling in from the west, pushing this front across the eastern side of the country into the irish sea. but it will take a while as we head through the night it will stay damp in central and eastern parts of scotland and england. further sleet and snow on the hills. further sleet and snow on the hills. further west, drier under clear skies it will turn cold with a frost. a hard frost in scotland. a ridge of high pressure building in

for easter day and most places should be day. a cold start for many with some frost around. a lot of sunshine, particularly in scotland and northern ireland. through the day the cloud willed by up and a greyer afternoon. it will remain cool greyer afternoon. it will remain cool. a few showers in eastern coastal counties. wet and windy later in the day in devon and cornwall. all courtesy of this next area of low pressure. it has mild air behind it, but ahead of it, this rain will push into cold air and we will see a mixture of rain, sleet and snow. snow even down to lower levels for central and northern wales, central and northern england and central and southern scotland and central and southern scotland and northern ireland and this could cause some problems in the afternoon. further south sunshine and showers and it will be turning mild we are temperatures in double figures. scotland will stay dry in the north. easter monday if you have

travel plans, bear this snow in mind. it will cause some disruption. as we head into tuesday, a very different feel, with much milder southerly winds and a typical mixture of sunshine and showers across england and wales. some heavy down pours in northern ireland. but notice temperatures from nine to 1a 01’ notice temperatures from nine to 1a or 15 celsius. this is bbc world news today. our top stories: sorrow and anger on the streets of gaza, as palestinians mourn the 16 protesters killed in clashes with israeli troops. russia reaches out to yulia skripal, demanding access to the daughter of the poisoned former double agent, who's recovering in hospital. two men accused of carrying out beheadings for the so—called islamic state complain they won't get a fair trial after losing their uk citizenship. and social media under scrutiny, the us considers asking visa applicants to hand over their online accounts.

hello, and welcome to world news today.