Deep Dive 08/07/2025 – Where will see a heatwave this time? – Met Office weekly weather forecast UK

Name: Deep Dive 08/07/2025 – Where will see a heatwave this time? – Met Office weekly weather forecast UK
Uploaded: 2025-07-08T15:37:07+00:00
Duration: 33 min 55 s
Channel: Met Office

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This is an in-depth Met Office UK Weather forecast for the next week and beyond. Another heatwave is on the way but they’re all different and the temperatures later this week will be different to the ones last time. Find out how hot it’s likely to get where you are and how long it might last. Bringing you this deep dive is Met Office meteorologist Alex Deakin.

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00:00Two heatwaves to talk about this week. We've also got a rocket launch and we might even throw in a

00:06little bit of maths. What's not to love about this week's Met Office Deep Dive? Welcome along. Thank

00:12you for being there. Thank you for watching. My name's Alex Deakin, a weather presenter and

00:17meteorologist here at Met Office HQ. If you are a fellow Met head like me and like most of the

00:23people watching, then do hit that like button. If you've not seen a Met Office Deep Dive before,

00:28make sure you're following us because we do this every Tuesday. A deep dive into some facets or some

00:35facets of what's really exciting about the weather at the moment. We love reading your comments. We

00:40love reading your suggestions. So please, please keep them coming as well. If you've got any questions,

00:46we often go through the questions in the deep dive and pick some of them out that we answer in our

00:51live show on Friday. So don't forget to tune into that. We go live on YouTube every Friday. Another

00:57reason to subscribe. If you watched last week's live on Friday, you'll have seen Honor talking to

01:04Stephen Keats, one of our deputy meteorologists, about the hot spell of weather coming up at the

01:10end of this week. So we were flagging it at the end of this week. And we're going to focus,

01:15as you might imagine, in this week's deep dive on the upcoming heat, along with a few other issues

01:23to contend with too. So yes, please do keep your comments. Please keep your questions coming in.

01:28As I say, we do read them and we do try and go through them. We do also take on board all your

01:33suggestions. And if you know someone else who's into weather, another Met head, then share the

01:38love. Let them know that we're on this channel known as YouTube and that we do this every Tuesday.

01:46Please do. OK, only one place to start, really, and that is with the heat. We're talking a hot spell

01:54coming up. It will be heatwave for some parts of the UK. Here's the bigger picture, the satellite

02:00sequence. Of course, we had a heatwave this time last week. Temperatures were peaking and we saw very

02:07high temperatures at the start of last week. Hottest day, I think, was the 1st of July. And since then,

02:14we've seen the weather patterns changing a little bit. And you can see that quite nicely on the

02:17satellite image here. If we go through the sequence over the last four or five days, you can see where

02:21the system's moving in across the UK. And you can pick out where the jet stream is by the position

02:25of the Cirrus, the high cloud. You can see the jet stream's here pretty much. And we have been on the

02:29cooler side of the jet. That's why we've had a relief from the heat. Back end of last week, we saw the

02:35change and it was a much cooler weekend with some welcome rain in places. And you can see, I say,

02:40that jet stream dipping down here. We've been on the cooler side of it. But now, if we pause it there,

02:47the current situation, you can almost see where the jet stream is going now. And we are now, instead

02:51of being on the cool side, we're merging onto the warmer side of the jet. So let's take a look at that

02:57in a bit more detail. Here's the pressure pattern. There's the jet arching up to the north. It's dipping

03:02down here, but it's now dipping down to the east of the UK. So we're on the warm side. Yes, there are

03:07weather fronts trucking in, but there's also this unit of a high pressure. And that is what's going

03:14to bring us the largely sunny weather from the middle of the week onwards. And that is what will

03:19allow the temperatures to be rising because we're on the warm side of the jet. Fast forward to Wednesday,

03:24the jet really kind of dipping down here. It's not much to it at this stage, but it is starting to dip

03:29down. And by Thursday, that's in more evidence coming down here and arching up over the UK. The high

03:36pressure's edging in, building in from the southwest. That high pressure's squashing the air.

03:41So that is heating things up. That's why we're seeing the temperatures rise. The high pressure's

03:46squashing the air. Obviously, the sun is beating down and the sun's pretty strong at this time of

03:50year. So temperature's ticking up day by day. Thursday, probably the first day, we'll see over

03:5430 degrees Celsius, but it won't be the last. By the time we get to Friday, well, that jet is really

04:00digging in now. There's a bit more about it. Proper kind of trough out in the Atlantic. And it's these

04:05troughs that generate the low pressures, pushing them up towards Iceland. And the high pressure is

04:10now just ambling a little bit to the east of the UK. You might imagine that the jet could push those

04:15weather fronts in, but it doesn't look like that's going to happen. It looks like it's going to dig

04:19down further here, push up further here, keeping those weather fronts out here. That's where the

04:24cooler air is behind this cold front. And I can show that if we put that. And that's where the cooler

04:31air is ahead of it. So temperatures building. We've got the warm air in place and the temperatures

04:35building by a process of the high pressure squashing the air and the sunshine coming

04:40through. And even by the time we get to Sunday, well, it may be aging a little bit closer. Not

04:45really until Monday that there's the possibility of something cooler coming in. But certainly

04:50Thursday, Friday, Saturday, Sunday, we will see those temperatures on the high side and not

04:54just across the southeast. We will see temperatures rising pretty much everywhere across the country

05:00this time around. Now, not all heatwaves are the same. In fact, every heatwave, like every

05:09summer, is different. There's been a lot of chats in the press. We've been talking about

05:14it here ourselves, about three heatwaves in a month. But actually, if you look at the maps,

05:18many parts of the UK have only really experienced one heatwave and some haven't experienced any

05:25heatwaves at all, as I can show you on this map here. If we take a look at what happened

05:30through the middle part of June, these are locations that saw three days in a row exceeding

05:36their heatwave criteria. And that's how we define a heatwave. Large parts of Wales, a good chunk

05:41of England did experience a heatwave through that middle part of June, the first hot spell. But

05:46notice parts of eastern England didn't reach that threshold. Most of Scotland didn't either

05:51and only tiny little pockets across Northern Ireland. In the more recent hot spell, the more

05:56recent heatwave, for some, you can see the patches here where we had three days or more over that

06:01threshold. And you can see, yeah, a good part of the Midlands, southeast England, northeast England

06:06did. But most of Wales didn't. I think all of Wales didn't. All of Scotland didn't. All of Northern

06:11Ireland didn't. So, yes, there's been a lot of chatter about how many heatwaves we've seen. But

06:15every heatwave is different. Every hot spell is different. And large parts of the UK haven't

06:21experienced any heatwaves yet. And only kind of a small area. I've actually had two in the past

06:27month. But where are we going to see a heatwave this time around? Well, if we put this map up,

06:34this is the projection for where we'll break the heatwave criteria. So three days in a row above the

06:40threshold temperatures that varies across the land. But we're likely to see a heatwave across much of

06:46England, the east of Northern Ireland and eastern parts of Scotland as well. But even to the west of

06:52Northern Ireland and the northwest of Scotland, we may not have three days in a row. But temperatures

06:56here are also going to rise. So this hot spell will be more widespread than the last one. And as you

07:02can see, a large part of England, well, it's expected to have a heatwave, be that Thursday, Friday,

07:07Saturday, or Friday, Saturday, Sunday, and some locations, maybe even Wednesday, Thursday, Friday.

07:12And there is a likelihood that many places will be still hot, even into early next week, as we will

07:17see shortly. So let's take a look at what the temperatures are going to do. Gradually rising,

07:24basically, over the next few days. If we fast forward to show that the peak of the heat, it's

07:28likely to be Thursday, Friday, Saturday, Sunday, Thursday, probably the first day we'll get over 30

07:33Celsius somewhere across the southeast, and then more widely on Friday and Saturday and until Sunday.

07:40But again, as I've talked about, it is slightly different. Notice it is slightly cooler around

07:45some of these coasts across the southeast. There's a hint as that high pressure builds to the east,

07:50we'll see a bit more of an easterly drift so that it won't be as hot this time around for the likes of

07:57eastern England, for the likes of the southeast up towards Cambridgeshire and East Anglia.

08:00And this map shows that quite nicely. This is the anomalies, the heat compared to the average for

08:09the middle of July. And this shows it quite nicely if we move forward to Thursday, Friday, Saturday.

08:14This is how much the temperatures are above average. And if we pick out Friday, you can see here

08:20that parts of the east coast of East Anglia may actually be pretty close to average. And the heat,

08:26the highest temperatures compared to average are in this zone across East Wales, down towards

08:31southwest England, but also up into parts of Yorkshire too. So it's that area there,

08:37which didn't necessarily have the heat last time around, particularly across East Wales and southwest

08:41England. Yes, it was hot here in the middle of June, but you didn't have the heat or as much heat last

08:47time around. And that's where we could see temperatures, more unusual temperatures. So in this zone,

08:52this darker red zone, we're talking eight, nine degrees or nine degrees or more above the average.

08:57Notice also Scotland is warming up at this stage. And if we fast forward to Saturday, that's quite

09:02interesting because we've got those dark reds now across parts of northern Scotland and the east of

09:06Northern Ireland. So we may not get a heat wave here because we may not get three days in a row.

09:10But Saturday, that could be the peak of the heat here and across Scotland. In fact, the peak of the heat

09:16in Scotland is probably likely to be Sunday along the Moray Firth. Whereas further south, again, it is

09:22hot, much hotter than average across most of England and Wales. But notice again, this zone, which is

09:27often the hottest part, will still be hot with temperatures getting into the high 20s, low 30s, but

09:32not as big an anomaly compared to the average as it will be further west. So that's what I'm talking

09:38about when I say every heat wave is different and we'll see different values in different parts

09:43of the country. So yes, we are going to see slightly different shifts to the temperatures over the

09:49next few days. The heat's continuing to build. Why is it getting hot? Well, these maps are showing

09:55the thicknesses. Honor talked about the thicknesses in last week's deep dive. Basically, these are the

10:01850 to 1000 hectopascal thicknesses. Basically, you take the atmosphere from 1000 hectopascals, 1000 millibars,

10:09which is close to the surface, and you go up through the atmosphere until you get to 850 millibars

10:15millibars or hectopascals. And basically, we've got between those two pressure levels, the distance,

10:21the thickness determines how hot the air is, how fundamentally hot the air is. Hotter air, more

10:28expanded, so you've got a bigger gap. You have more decameters, more distance between that 1000

10:34hectopascals and the 850 hectopascals if you've got the hotter air. And that's what this is showing here

10:39in the thickness pattern. On Thursday, still quite cool air across the northwest of Scotland. There's a weatherfront in here,

10:45and the highest temperatures, the highest thickness, the warmest air is in that zone from East Anglia down to

10:52the southeast of Wales. By Friday, we're getting the higher values across the core of the country, across the

10:59Midlands, into East Wales. There's darker pinks and even the purple in there. Look at this. On Saturday, that's the peak

11:05for England and Wales, 142. That says 142 decameters. That's how high you've got to go up before you get to the

11:11850 millibar, 142 in here. But notice across Scotland by Saturday, compared to Thursday, see that jump across

11:18Scotland and even Northern Ireland into the red zone here as well. So that's where the highest temperatures are likely to be on

11:23Saturday. But Scotland isn't done because Sunday sees the peak here. So on England and Wales, Sunday, the air is

11:29slightly cooler. The thicknesses are slightly down. So the air won't be as hot on Sunday. We'll still see over

11:3630 degrees, but it won't be as hot for England and Wales, probably low 30. So the peak for England and Wales,

11:41probably 33 in this kind of zone across East Wales and the West Midlands. But the peak in Scotland could be on

11:50Sunday across the north. That's where the thickness is highest here before we potentially see a change into

11:55Monday. And again, more on that in a second because there is a bit of a question mark about that. But that's how the air is

12:01changing. So it's heating up. Thursdays, the heat in the south east, that's probably the first day over 30 degrees.

12:06Then more widely across England and Wales, the heat rising in Scotland and Northern Ireland. The peak of the heat across Scotland and Northern Ireland

12:12Saturday and then into Sunday, particularly across the north and in the south, actually temperatures across England and Wales,

12:19probably a degree or so down. Still hot on Sunday compared to Saturday. So, yeah, that's how the temperatures progress

12:26over the coming days. Just wanted to show you this as well. It's an interesting chart. Big thank you to Dan Holley, by the way.

12:33He's helped me a lot with with today's presentation. He's our deputy chief today. He was giving a brief this morning.

12:38Every every morning, the chief and then the deputy chief give us a brief on the current weather. Dan's been looking at this medium range

12:45and basically went through it brilliantly this morning. And yeah, gave me all these charts, the ones that he used, because this is really

12:52quite interesting as well. This is the probability, the chance of reaching 30 degrees showing there across a good chunk of England

13:01and Wales. But notice that shift, the higher chance there across the West Midlands, Herefordshire, Gloucestershire

13:07into the east of Wales and down across the southwest as well, extending up into parts of Yorkshire.

13:12That's the chance of getting over 30 degrees on Friday. But you can see here by Saturday, parts of Northern Ireland,

13:19parts of Scotland, just that chance increasing. So there's no chance Scotland, Northern Ireland getting to 30 on Friday.

13:24But by the time we get to Saturday, that chance has started to increase. And if we just play through into the next

13:30year, hopefully it's going to show Sunday. Yeah, it's going to pick out that North Coast, the Murray Firth there, actually quite

13:37a high chance. It's a smaller zone on Sunday across Scotland, but there's a higher chance in the Murray Firth of reaching

13:43over 30 degrees Celsius. And that is in part due to the fern effect with the breeze coming in over the mountains and

13:50lifting the temperatures. We've talked before about the fern effect in Scotland. That could play a significant part.

13:55So Sunday, the Murray Firth signalling there could get up to 30 degrees, perhaps 31, perhaps 32. Why is that significant?

14:04Well, it'd be hot for that part of the world, obviously, but potentially pushing station records as well.

14:11This map is showing the site records for the year, not just for July, although they're probably pretty similar for many, many places.

14:18July is the hottest time of the year. But just notice on the Murray Firth there, those temperatures 31.2, 31.6.

14:25That's their highest temperature on record. And we could be pushing records in this zone.

14:30Notice actually the records there in Stornoway, Outer Hebrides, 26.3 degrees Celsius.

14:35Yeah, it might not be far off that here even because the warmth will even push into the far northwest as that weather

14:41finally clears through the weekend. But a greater chance in this zone, because the winds travel over the mountains, over the Cairngorms,

14:48and you get the fern effects. It comes down the other side. It's much drier air. It's much sunnier air.

14:52And you've had that heating. And so the temperatures rise because of the fern effect.

14:56It could be quite cool on the east. Well, not cool, but temperatures could be, could easily be 10 degrees lower on the east coast of Scotland

15:03if the breeze is coming in that direction, then up over the mountains and into there.

15:08So it all depends on that subtle position of the high pressure and where it sits as we get into the weekend.

15:15Take the jet stream off. The position of the high will dictate the winds. Just a subtle shift will determine which way the winds are blowing.

15:25And, of course, that will have a big impact because the sea, although still, although it is very warm at the moment compared to average,

15:32again, as we'll see shortly, it is still very cool compared to the land.

15:36So it does make a big difference, that subtle shift in the wind direction.

15:42Let's stick with those temperatures in the sea because, as I said, the sea temperatures at the moment are anomalously high.

15:54I did say at the start that we had two heatwaves to talk about.

15:58I've talked about the heatwaves of the temperatures over the land.

16:00But we're actually already experiencing a heatwave, a marine heatwave.

16:04The Met Office wrote a blog about that. Ryan wrote a blog about that earlier this week.

16:08You can see that on the Met Office website.

16:10And this is the current temperature anomaly in the sea surface temperature.

16:14It's taken from last week. And the darker reds, where we have a marine heatwave of category two or three.

16:21Those patches around here. So temperatures are well above average.

16:2417, 18 degrees through the channel, even some pockets of 19, even 20 Celsius across northern Scotland.

16:30Closer to average temperatures here, which means there are temperatures in the sea are about 13, 14 degrees Celsius.

16:35So, yeah, if you think about the temperature in the sea here, 13, 14 degrees compared to the temperature of the land that it could be at the weekend,

16:42we're talking close to 20 degrees higher, certainly high teens more temperature on the land.

16:48So a lot of people will be heading to the beach this weekend.

16:50Two things to be aware of. Sea temperatures, although well above average, are still cool.

16:57You can still suffer from shock, from cold water shock.

17:00So take the advice of the RNLI. There's loads of really good stuff, loads of good advice on the RNLI.

17:05I would follow them on social media. They post really good stuff on TikTok as well, the RNLI.

17:09So give them a follow. And there's lots of good advice about how to deal with cold water shock,

17:15because although it is warm in the seas around, it is still going to be cold relative to the temperatures that we are seeing.

17:22So that is the second heat wave I wanted to talk to you about.

17:26The next question. How long will this heat wave last?

17:31We've seen that Thursday, Friday, Saturday, Sunday, four days of hot weather pretty much across the UK.

17:35And the models are in really good agreement.

17:37So, you know, sometimes at this kind of stage, there'll be a lot of uncertainty about the weekend.

17:42Well, there'll be bits and pieces of clouds or the exact wind direction.

17:46And that could generate some hard, low cloud, misty conditions around some coasts.

17:51So that kind of level of detail. Yeah. OK, we we can't pin that down at this stage.

17:55But but the models are rock solid that we're going to see high pressure moving in, move to the east.

17:59Hot weather for the vast majority into the weekend.

18:03The big question mark then comes, when is it going to change?

18:06And we saw earlier the cold air is not cold air, the cooler air is tucked in behind this weather front here,

18:15which gets closer and closer and closer and closer, but never really kind of pushes in, stays out.

18:21So for the weekend, we are still looking at the hot weather sitting across the UK.

18:26But early next week, that could change with the emphasis on could.

18:31That's just looking at one model. That's just the Met Office model.

18:34As I say, most of the main models do agree.

18:37But when we're talking this kind of range, we look at ensemble forecasts.

18:41That's how we generated the chance of seeing 30 degrees by running the model many, many times.

18:48And that gives you a chance. So if two of the models out of the 50 are saying that they're going to get over 30 degrees,

18:54then that would be a 4 percent chance. So that's how the ensembles for work.

18:59And in terms of this, who doesn't love a spaghetti plot?

19:03This is showing the potential position of the cold front and therefore the cold air.

19:10Now, it looks a bit of a mess and it is. But actually, you know, I've seen I've seen a lot worse.

19:15I was going to compare it to my son's drawing, but actually he's five now and he's getting quite good at drawing.

19:20So that would be a bit harsh, bit unfair on him. But this is showing the potential when you run the model many times.

19:26Each of these blue lines is showing where that run of the model wants the cold front to be at midday on Monday.

19:34And the green line is where the main run is, the deterministic run, the main computer model run when we just look at the one.

19:43That's where the green line is. This is from the European model. So that's the ECMWF position of the cold front.

19:48So you probably can't see it very well. So I'll zoom in a little bit and maybe I will see if I can draw on the British Isles.

19:57What color should we use? Let's use red. So there's East Anglia down to the southwest.

20:02There's Wales and there's Scotland. So you can probably see it a little bit better.

20:07Now there's Northern Ireland, Republic of Ireland. So the European model has the cold front in here,

20:13pretty much slicing right down across the UK. But you can see that the main one is ahead of most of the ensembles.

20:22Most of the other runs are further back. So if you just took that one, you think, OK, it is going to turn cooler for Western Scotland and Northern Ireland on Monday.

20:30But when you run it many times, you see that actually that's not necessarily the preferred solution.

20:37The most likely outcome is that it's somewhere back here because there's more of them back here.

20:42If you want more on ensembles, there's a good video on our YouTube channel about what they are and what they mean.

20:49You can look that up. But it's a higher chance that the colder air is further back here than it is pushing in.

20:56So there's a bit of a question mark about when we see the cooler conditions coming in across the UK.

21:03But it does look, most of the models do bring something a bit cooler in by Tuesday or Wednesday next week.

21:09But there's a big question mark about the timing on that.

21:12Another way to use ensembles is with this distribution, these graphs where this is called a meteorogram.

21:20This one is for a place called the Moor of Granary. Again, big thank you to Dan for spotting this out.

21:25It's just inland from the Murray Firth. And this is showing the temperature profile here in this one.

21:32Temperatures going up, up, up, peaking here. The purple barbs up here, that's the cloud.

21:38You can see the cloud drops for the weekend Saturday, Sunday, so more sunshine.

21:42And this is showing the chance of precipitation, how much rain we're likely to see.

21:46So it stays dry and then there's an increasing chance of seeing some rain from Monday onwards.

21:51You can see it does dip. The temperature profile dips down here once we get past Monday.

21:56But there's still quite a bit of uncertainty and it just shows how high those temperatures could get.

22:00That's the 30 degree. Again, we'll zoom in a little bit because I can show you that versus Swindon.

22:05So this is the Moor of Granary versus Swindon on the lower chart here.

22:10And that's showing those temperatures rising and then probably dipping as we go into the early part of next week.

22:15But that question mark about when due to the position of that cold front.

22:19This is for Swindon. So in the south, how long is the heat going to last?

22:23Greater certainty. The box and whiskers plots are smaller for Swindon that we're going to see those temperatures.

22:29And again, up over 30 degrees for Friday, Saturday, Sunday.

22:34Monday, there is a chance that cold front could be through further.

22:37So that's why that tail is a little longer. Oh, gone down.

22:41Let's go back to there. Play it through. Lost it. I'll come back to it. There we go.

22:51That's probably the best thing to do. It does dip off even in Swindon next week.

22:56But there's a hint there that it actually may start to rise next week.

23:00So although it may turn a little cooler as we go into next week, there is no guarantee that we're just going to see that fresher air.

23:08And all of a sudden we'll see Atlantic conditions.

23:10It's more likely actually across the south, the air temperature dip a little bit.

23:13But the warm air may well stay close by and temperatures could easily stay in the mid to high 20s well into next week.

23:21So, yes, hot this weekend, probably turning a bit cooler early part of next week.

23:28The heat may not be too far away across the south and even further north temperatures, even in the more granary generally.

23:34The most likely scenario is that they're still above average here too.

23:39Aidan will have more. I want to just confirm who he is.

23:42I'm pretty sure it's Aidan doing the 10-day trend tomorrow.

23:44So the 10-day trend tomorrow, another reason to subscribe.

23:47You can watch him. No, it's not, is it? No, it's not Aidan tomorrow.

23:51I think it's on her tomorrow actually doing the 10-day trend.

23:53I should have checked that before I came, but watch the 10-day trend tomorrow and whoever it is will have more on that and more detail all about that.

24:02So, yes, hot this weekend and then it turns a little bit cooler.

24:07What else did I want to talk to you about today?

24:09Oh, my visit to Germany.

24:11This time last week, this time last week, I mean, you think 33 is hot.

24:15This time last week, I was in 36 degrees in Germany because I was very lucky to go to Umetsat, which is the headquarters of Umetsat, which is based in Darmstadt, which is just south of Frankfurt in Germany.

24:32And Umetsat basically run the operations with weather satellites across Europe.

24:36And that's me with an old weather satellite.

24:39But I was there to watch the launch of a brand new satellite.

24:43So last Tuesday evening, I was very excited in Cape Canaveral.

24:46A rocket went up and on board that rocket was a very, very important payload.

24:51A brand new satellite.

24:54That is the glorious picture of the rocket taking off in Cape Canaveral.

24:59Cape Canaveral.

25:00That's a post on Instagram by Umetsat.

25:02Go and follow them, actually.

25:03Really interesting posts across social media, Umetsat.

25:07That's their post on Instagram showing the rocket being launched into space.

25:12And on board was this little beauty.

25:16Say little beauty, quite a big beauty.

25:18That is the, uh, a scale model of the actual satellite that was launched.

25:23And it's a very special satellite.

25:25I'm just going to play through.

25:26It's a bit, yeah, bit too, bit too fast.

25:29That isn't it really?

25:30Uh, so let's get rid of that.

25:32Let's go back to, let's go back to the rocket launch.

25:35Cause that's a thing of beauty.

25:36Let's go back to that.

25:37Um, so yes, on board this rocket, MTG-S1, the second in the third series of, um,

25:47um, satellites, um, Umetsat satellites.

25:53And this one, second in the third generation.

25:57So we've had the second generation, the first generation started in the seventies.

26:00And then through the noughties, there's been the second generation.

26:03And this was part of the third generation.

26:05The second one in the series of six.

26:07This one's really interesting.

26:08Really, really is a game changer because it changes the way that we look at, uh, Europe.

26:15It's going to be, give us new pictures every 30 minutes of a temperature profile.

26:20So actually going to paint a 3D picture of the temperature through the atmosphere, temperature and humidity.

26:25And that's going to be a game changer because it will give us a better idea of thunderstorms.

26:30Spot thunderstorms before they form.

26:32It'll give us a better idea of their life cycle of thunderstorms and where they go and where they're likely to go next.

26:38It'll make us better at forecasting them.

26:40It's also going to give us a better idea of forecasting things like fog, mist and low cloud.

26:45And not just one sensor on the satellite, but many.

26:49And another one, uh, the Copernicus Sentinel-4, which is going to be better at picking out things like particulates,

26:55be better at monitoring wildfires and, uh, aerosols in the atmosphere that can have serious health impacts.

27:02And so, yeah, a lot of really cool data going to come out from this new satellite.

27:06The data should start to be available next year.

27:09It's gone up now.

27:10It's in a, um, a transit orbit.

27:13Then they'll put it in the right orbit shortly.

27:16And yeah, in a couple of years, it'll be fully operational.

27:18But this time next year, hopefully we should be getting some data.

27:21So a very exciting launch and I was very lucky to be able to go to Germany.

27:25And there's more on that on the Met Office LinkedIn page if you want to see.

27:29But I did want to show one more thing about the satellites because I want to show you this diagram,

27:36which I stole off the NOAA website.

27:40The two different types of orbit of satellites.

27:43Now, the one that went up last week and where most weather satellites or many weather satellites live is in this orbit here.

27:54It's called a geostationary orbit.

27:56And it's important because it's sitting over the same place.

28:01So a lot of weather satellites will sit over the same place so that you can get an idea of how things are developing,

28:08how things are changing through the day.

28:10So the weather satellites, we call them geostationary satellites.

28:14They sit above a certain place.

28:15And this one will sit above Europe and take pictures of Europe, bits of North Africa as well, and parts of the Atlantic.

28:21But it's going to sit above the same place by doing this orbit.

28:24It's further out than this orbit.

28:26And that's called a polar orbiter.

28:28A different type of satellite is a polar orbiter.

28:31That's generally a lot closer to Earth.

28:33And so you can get high resolution pictures.

28:35And it goes around the poles.

28:37And so you only get a picture above where you are probably about once a day.

28:43If you look at the same time every day, you get the same this game picture, but you're only getting one a day.

28:47So there's different advantages to those different types of orbit of satellites.

28:52This one's traveling faster.

28:54This one, if you want that in the same position, it's got to be moving at the same speed as the Earth.

29:02So that's a set distance away.

29:0536,000 kilometers.

29:07That is where you have to be.

29:08Just under 36,000 kilometers.

29:10That's where you have to be.

29:11If you want to sit and sit over the Earth, move at the same speed and take the same, be able to take the same picture every half an hour because you're sitting it.

29:21So it moves around.

29:22So if you're under it, you see it and it's just moving around with you.

29:24Whereas this one, the polar orbiter, is moving much faster.

29:27It's closer.

29:28So it gets better, higher resolution pictures.

29:30But you only get one a day because of its orbit going around like that.

29:35And I just wanted to do some maths because I thought this was quite fun.

29:39Maybe it's not.

29:40Maybe it's just me.

29:41But it was a guy called Kepler.

29:45Kepler was a scientist from way back when.

29:52And he was the guy who basically worked out that planets go in elliptical orbits around the sun.

30:01He was following on from the work from a guy called Copernicus.

30:04He was one of the first people to suggest that the sun was the center.

30:09It was the Earth was going around the sun rather than what had been popular belief until that, that the Earth was the center of the universe and everything was going around the Earth.

30:16And that's kind of what you'd think, wouldn't it?

30:18If you were sitting on the Earth and you saw the sun coming up and going down, you'd think the sun was going around us.

30:22But we now know that that's not actually true.

30:24The Earth is going around the sun.

30:26And Kepler came up with three laws, three famous laws that defines the way that we work out what planets are doing.

30:35Now, the third law is the most important one here.

30:39So let's do a little bit of drawing.

30:44That's the sun.

30:45This is good, isn't it?

30:47And the planets go around the sun like that.

30:53They don't go in a circular orbit.

30:55They go in an elliptical orbit like that.

30:58Now, this distance here is known as the major axis.

31:05And that distance there is known as the minor axis.

31:08Now, Kepler's third law states that the time it takes to go around this orbit squared is directly proportional to this distance here, a cubed.

31:27Now, the maths works out, there's a constant in there.

31:30The maths works out depending on the mass of the Earth and the mass of the Earth, pi.

31:40You can work out then what T is in relation to A.

31:43Now, T has to be the same as a day.

31:48So, because you want it to sit in the same place.

31:51So it has to be going around the Earth at the same speed as the sun, effectively, or the same speed that we're going around the sun.

31:57So it sits at the same speed as the Earth is rotating.

32:00So T is, T squared is directly proportional to A cubed.

32:03And when you put the maths in, that tells you that A, when you put in the maths, is actually equal to about 42,000 kilometers.

32:16Now, those of you paying attention will say, but I said the satellite sits at 36,000 kilometers.

32:24And that's because that is to the distance to the center of the Earth.

32:28And so you've got to take the radius of the Earth off.

32:30So A minus R is equal to 36,000 kilometers.

32:37So that is the distance, just under, that all these geostationary satellites sit at.

32:43So they can sit in the same place and look down on Earth and take the same picture every half an hour.

32:49And that's the difference between a geostationary satellite that's staying in the same place and those polar orbiter ones that are going round and round and round.

32:56I hope you like my maths. Is it better than my art? That's the big question.

33:00And yeah, I hope you enjoyed that little bit of a sidetrack.

33:05But I quite like that because I studied astrophysics at university.

33:08So I thought you'd enjoy that.

33:10Let me know in the comments if you did or if you didn't.

33:13But that's pretty much it from me for this week.

33:16Again, big thank you to Dan Holley, Deputy Chief today, and to Neil Armstrong, who is the Chief today.

33:22Both helped me out quite a lot with talking about today's temperatures.

33:25Lots of things for you to check out.

33:28Go and check out the UMET set.

33:30Go and check out our other videos about ensembles as well.

33:34Make sure you give us the thumbs up.