QnA - Should you pee on a Jellyfish Sting?

10 July 2018
Presented by Chris Smith.

This week, The Naked Scientists are swinging into summer! Guests Jane Sterling, Jim Bacon, Laurence Kemp and Howard Griffiths take on your holiday themed questions, including: Why do we get heat waves; how do you treat a jellyfish sting and why does the sun bring out freckles? Plus, can you separate fact from fiction in our fiendish summer-themed quiz?

In this episode

A depression system from above

05:57 - What is a jetstream?

What is causing the current heatwave?

What is a jetstream?

Chris Smith proposed this hot topic to Weather Quest’s Jim Bacon...

Jim - Really good question. Like all good questions there are short answers and probably fairly long answers. I'll try and make this one a fairly short answer. The atmosphere consists of a lot of heating that goes on around the equator, and not very much heating around the poles, and it's a very imbalanced system. And the jet stream is, in a sense, a response to the imbalance when you get warm air very close to cold air. You could say, you’d think that it would just degrade gradually from the equator to the poles and gradually get colder. But in actual fact, in the real world, what happens is you get zones where it gets to be a very intense demarcation between two different air masses: say, one coming up from the south from the tropics, and one coming down from the north and the poles. And to make the atmospheric forces balance the motion, the jet stream is a strong wind that forms to do just that. So you get around the whole northern hemisphere. I dont know, it's probably easier to go into electronics here, and picture an oscilloscope trace with a sine wave on it, and if you had that and joined it up all around the northern hemisphere you'd have a complete set of undulating ridges and troughs going around.

Chris - Why does it wiggle like that?

Jim - Well it wiggles because of the instability in the flow, and there are two or three types of wave motions. So one of them is what's called a Rossby wave, which is a very long wavelength caused by disturbance over big mountain ranges. And it's a planetary scale thing and you might fit about five of these around the whole northern hemisphere and then superimposed on that you'll get a slight disturbance, a small perturbation, we call them. Which is the sort of thing that represents lows that travel across the Atlantic and give us our weather. And those features can transport warm air northwards much quicker and bring cold air southwards. And they have the ability in this flow stream to amplify and they grow into much bigger systems. So eventually what happens, our nice sine wave, given the right conditions and instabilities, can distort enough to become very high amplitude waves on the oscilloscope. And the general rule is if it's a very shallow thing, they ripple across really quickly. So our weather is very changeable totally unlike now. It changes one day you've got a low coming in with a lot of wind. The next day you've got a fine spell of weather and then the next ripple comes through and brings another low. But what happens when it gets bigger is that the pattern slows down, and the pattern slows down and can at some stages come almost to a halt and tend to want to move westward. So instead of our systems coming from the west to the east, they can want to go from the east to the west, and that's what we in meteorology call a blocked weather pattern. And it's those blocked weather patterns that are associated with particularly long lasting spells of weather where you get the same type of weather for several weeks instead of changing every other day. And there's one special case of blocked pattern where this nice sine wave forms a very contorted pattern which looks like the Greek letter Omega. And that virtually can stay locked to a longitude on the globe for weeks and weeks at a time. Some of you will, doubtless in this country and I'm sure there are equivalences all around the world, where the pattern has become locked in our country. We had, in the UK, we had a big drought in 1976 and that was one of these blocking patterns. We had a barbecue summer, famously, when we didn't actually have a summer when we got stuck in the loop of this blocked pattern.

Chris - And we just got continuously bad weather?

Jim - Continuously bad weather! Because the whole pattern stops moving across the Atlantic and it's stationary. So the interesting thing is you've got to be stationary underneath the block, the region; the Omega. And if you’re not, you’re having the bad weather and that was the barbecue summer. So the idea of it being a good summer was that the block would stop with us under the ridge. But in fact, it was only a few degrees of longitude out, 10 to 20 degrees of longitude out, and that meant that we were under the bad weather. So we had a summer like that. This year, and in ‘76, we are under the top of the Omega.

10:20 - Why does burnt skin peel off?

Why does burnt skin flake instead of becoming beautifully bronzed?

Why does burnt skin peel off?

Chris Smith asked this question to dermatologist Jane Sterling:

Jane - Well I think that's a great question but we're all thinking about the beautiful bronze goddess rather than the flaky person, aren't we? Let me take the end of the question first because I think there is something aesthetically very pleasing about even toned skin and perhaps not too pasty. In this country where we don't always get a lot of sun, as we've just been hearing, that little bit of a hint of colour to the skin is regarded as being attractive. But I think the quickest way to being a beautiful bronze goddess is probably to have a spray tan. So I'll just put that one in first. But the sunburn business, very important. So sunburnt skin is bad news. That means that you've had enough damage from ultraviolet light to cause damage to your DNA, and sunburn is the process that the skin is going through to try and repair the damage that's actually happened from the ultraviolet light.

Chris - So there is inflammation in the skin after you've been hit by that deluge of UV from the sun?

Jane - Yes. So as the skin tries to recover from that damage, it's inflamed and then as inflammation settles you get the peeling just like you do if you have a scratch or some other sort of inflammatory process in the skin. Eczema, psoriasis, that are common skin disorders, they both have inflammation. They both have flaking.

Chris - So does that mean to get a suntan you have to damage your skin en route to becoming a bronze goddess or god/

Jane - Yes. You do do a little bit of damage every time you go out into the sun, but if you are definitely pink and burnt then you've done a lot more damage and there's a lot more recovery to happen.

Chris - So is the best approach to do a sort of graded exposure then? you have a little bit of sun exposure and go a little bit brown, and then a bit more exposure and go a little bit more brown, if you're seeking to adapt your skin to sun exposure so you don't ever burn but you just accrue a sun tan?

Jane - That would be the perfect process. So on holiday, it's always best to never get burnt. And you have to know your own skin and the sun and the the intensity of the sun quite well to know exactly what that means. But if you can avoid getting any pinkness to your skin when you go out in the sun, if you go to the med, just have enough sun exposure to get a little bit brown then you'll be doing the best you can for your skin.

Why is my hayfever so bad this year?

Chris Smith asked this question to Plant Ecologist Howard Griffiths and GP Laurence Kemp

Howard - I think I better just say, first of all, I'm speaking from the plant perspective and we may be better ask Laurence to give us to the more medically based solution. But I think it's probably due to the fact in the UK we had a rather late spring this year and then it suddenly went very dry. And so we've had a very short growing season. And there are some plants which are wind pollinated, which means that they produce huge amounts of pollen, which can then be dispersed on the wind to find the female parts of adjacent flowers. Plants like many trees and many grasses, of course. And so I think that the problem has been that there's just been not much rain to wash that pollen out so there’s just been a huge amount around.

Chris - And is that your experience, Laurence, you seeing lots of patients complaining of hay fever symptoms?

Laurence - Yeah. I mean much more than the normal. I’ve been a GP in South Cambridgeshire for 7 years and this is definitely the worst year. So normally, probably this time of year, maybe four or five consultations a week with people with hay fever problems. I think we’re kind of more like 20, 25 at the minute. Certainly a bad year for it.

Chris - And if you see a patient with those symptoms, what's your advice?

Laurence - For the majority of people with hay fever, and remember it's a really common condition, about one in four people suffer with hay fever, most people it can be fairly mild. They can get an antihistamine from the chemist, maybe a steroid nasal sprays, some eye drops. It's only a small minority of people who are going to get more significant symptoms that’s going to need to come see a doctor. And actually if they see me, generally speaking, it's just similar types of products but a little bit stronger prescription strength, more potent antihistamine. Usually we can get it fairly under control. You know the good thing is it's something that goes away after a few weeks usually anyway.

15:02 - Why do my ears pop on planes?

What's going on in my ears when they pop after a flight?

Why do my ears pop on planes?

Chris Smith asked this question to GP Laurence Kemp...

Laurence - So that's a pressure thing that's going on there. If you think of how the ear works. From the outside of the ear there's a small little air canal, which takes you to the eardrum. And then the other side of the eardrum, you got what we call the middle ear. Now in order for the hearing to work properly, you need an equal pressure on either side of the ear. And that way the drum will vibrate when the sound waves hit it and that will be taken through to the unit where their hearing happens. So when you go up in a plane, for example, although they're pressurized cabins, they're not fully pressurized to atmospheric pressure. So as you go upwards the pressure within the cabin drops off a little bit, that causes your eardrum to gradually bulge outwards because the pressure within the middle ear is higher. Now your body's way of resetting that pressure difference is to open up a little tube called the eustachian tube, which runs from the middle air into the back of the nose. And we open up that tube by yawning, by swallowing. So you noticed in a flight, as you go up your ears might begin to hurt a little bit. You swallow, you yawn, maybe you pinch your nose and blow and that opens up these tubes,  equalizes the pressure and that usually relieves the symptoms. Same thing when you come down again, your ears get used to that slightly lower pressure. And as you come down again same thing happens, but in reverse. That time you're letting air in. Interesting thing is that children or babies in particular, kind of children toddler age, their tubes are relatively much smaller and open much less than an adult, which is why it tends to be the young kids on the flight that are crying when you go up and go down rather than the grown ups. And maybe you’ve  just tolerated it a bit better.

Chris - It's a similar phenomenon when one dives into a swimming pool and swims very deep or goes scuba diving. If you go scuba diving on your holidays then you may feel pressure in your ears and you blow down your nose, holding your nose, and you can equalize the pressure that way. It's the same phenomenon.

Laurence - It's the same thing but obviously with water being so much denser than air actually, you can achieve much greater pressure changes when you go up in an aeroplane. Although you're going to 36000 feet, because it's pressurized, that pressure drop is kept fairly modest. If you go diving, about 40 meters under water, there's enough pressure that you can seriously damage your eardrums, unless you know what you're doing.

Chris - Jane?

Jane - Yes, I was just going to ask. I know they often hand out boiled sweets, didn’t they, just before you land on a plane. I never found that helped very much. I find that yawning is much easier to make your ears popped. I just wonder if the little bit of swallowing you do, probably after boiled sweets, does anything or is it just bad for your teeth?

Laurence - I think swallowing helps it opens it up again but I dont think its near as effective as holding your nose and having a good blow to open them up.

Chris - Bad for your teeth, great for your dentist’s wallet.

Suncream

18:23 - How suncream blocks UV

How does sunscreen protect your skin?

How suncream blocks UV
with Andrew Farrer, Cambridge Science Centre

According to Cancer Research UK, there were almost 16,000 new cases of melanoma skin cancer in the UK in 2015, with 86% of them preventable. So just how important is sun cream? Chris Smith found out how it works from Andrew Farrer from the Cambridge Science Centre...

Andrew - So what we're going to do is I've got a standard fluorescent highlighter pen, the kind that we've all used when we've had to revise, or marking important documents. What I'd like you to do with it is just write something on your arm please.

Chris - Ok, so I'm taking, I’ll choose yellow because that's nice and bright

Andrew - Yellow is a good colour, yes.

Chris - I think I'm going to write ‘naked’. There we are. So I now have the giant words ‘naked’ in fluorescent ink down my forearm of my right arm.

Andrew - So what's really cool about fluorescent markers is fluorescence is actually a chemical thing where UV light is too high an energy wave from the sun for our eyes to detect. But if it hits a fluorescent chemical, what actually happens is that chemical bounces the UV light back, but it lowers the energy into something visible.

Chris - Right, so it takes the energy out of the UV and then converts it into a color of light that we can see .

Andrew - Effectively, yes. It's the electrons in the atoms and the molecules are absorbing the energy of the UV wave, and they bounce it back - they reflect it back; this is how we see all colour. But the electrons don't give all of the energy back again; they lengthen the wavelength of the light wave, so this becomes visible. So if we have these UV torches that we have here in the studio and shine them on your arm, what we should see is that the word ‘naked’ suddenly becomes very bright.

Chris - So I now have a very brightly glowing ‘naked’ on my forearm!

Andrew - Exactly, and this is the conversion of UV back to visible light and makes it glow. We use this in police vests, in the kind of vest you see on workmen using on the side of the road. So this makes that bright yellow-green that they’re wearing even brighter because the UV from the sun brightens it up again. Well what we have here is a tub of a factor 50 sunscreen, and what I'd like you to do now is just take a small dab of it on your fingers and just cover part of that word, the word ‘naked’.

Chris - So you want me to smear a dab of...

Andrew - Just to smear - dab the other half of the world so we can see the comparison.

Chris - Right. So I’m just - I’m just liberally putting this over half the word naked. I might have got a bit carried away, but I’m now covered in suncream as well - I won't touch any more knobs in the studio. Right. Okay.

Andrew - So the point of our suncream is to block the UV from reaching out skin, so it’s going to absorb all of that UV light before it hits your skin and also now before it hits the ink of the highlighter. So if we shine the UV on it now, the part of the word that is still exposed, that you didn’t put suncream on, still glows, when underneath the cream, there’s no glow at all. We can still see the yellow colour faintly, the actual ink, the normal colour, but we don’t get that fluorescence happening.

Chris - I mean the amount of UV light from this UV torch I’m shining on my arm that’s reaching the dye to make it glow is massively reduced where the suncream is. How exactly does the suncream do that?

Andrew - Exactly. Well, a factor 50 absorbs the UV light. Well, all suncream absorbs the UV light, about 2 percent of the UV rays will get through a factor of 50. But just like any light is absorbed by the molecular structure of whatever chemical, whatever substance it’s bouncing off, in some cases it’s bounced back at us. In this case the suncream is just retaining all of that energy, converting it in a different way.

Chris - And Jane when sun cream says factor 50 or factor 30, in practical terms, what does that mean?

Jane - that number number relates to the amount of time you should be able to spend in the sun, so that you can judge how much damage the sun is likely to do to you. But the problem about the way you were putting the cream on, if I might say, is that you had a big thick smear. And nobody wanders round the street, or lies on the beach, or goes for a swim with that sort of thickness of sunscreen on, and the tests that were done, when they're done, they assume quite a thick layer of sunscreen, and most people put a tiny smear on, and so they're not really getting the proper protection from their sunscreen.

Chris - So you’re saying you should be doing what I did on my arm, because when I go on the beach or when I go sailing and things, I do put a really thick smear on my nose, because I'm aware of the fact my nose has been burned in the past and also it's quite exposed. So that’s what you should do.

Jane - Absolutely, the ears and nose and top of your head are really, they get a lot of sun. So in an ideal world you would put a thick layer on, but of course nobody is going to do that, so you do need to make sure you repeat application during the day. It's estimated that if you are lying on a beach, let's say in your swimming trunks, and you’re just going to stay there all day, you should certainly apply cream at least three times a day and that you should use about 30 mls or 30 grams for each application. So most people when they go on holiday they probably take one bottle of sun protection cream with them, and that's way not enough. So the other thing is the two different types of sun protection in sunscreens, and the best ones to go for are ones that both reflect and also absorb. You were talking about the absorbing, absorbing properties of suncreams, but the ones that reflect which of course perhaps do look white when you put them on, they give you extra and better protection than just using the energy absorbing ones.

Red sky at night...

Does a red sky at night really mean nice weather ahead?

Chris Smith put this question to Jim Bacon from Weather Quest...

Jim - I kind of have a soft spot for weather sayings, because when I was younger I used to work on a farm, and the guys there would have a great innate knowledge of what the weather did, and they would use these weather sayings as if they were kind of gospel, and most of the time they are, and what I like to do as a meteorologist is to look at some of them and think what would be the physics behind it. So the ‘red sky in the morning shepherd's warning’ and so on, is to do with the fact that in general, these were developed developed at times before we understood meteorology. So it's going back to the Middle Ages and before, when people had to try and remember what a certain sky meant, and red sky in the morning means the sun rising in the east is shining on clouds coming from the west, and most of our weather comes from the west. So it was a sign of bad weather. And red sky in the evening, you know, was the reverse, and it meant that the sun setting in the west was shining on the clouds going away to the east, and therefore the bad weather was going away. So weather proverbs are not without value. They've been honed over the years. The trick is really to know when to get them out the tool box and when to leave them in there, because they don’t always work.

25:58 - Quiz: Frumious bandersnatches and tasseled wobbegongs

How do our brainy panel fare against the fiendish Naked Scientist quiz?

Quiz: Frumious bandersnatches and tasseled wobbegongs
with Howard Griffiths, Cambridge University, Jane Sterling and Laurence Kemp, Addenbrooke's Hospital, Jim Bacon, Weather Quest

It's quiz time for our panelists. From animal inventions to tourist traps, Chris Smith pits Jane Sterling and Jim Bacon against Laurence Kemp and Howard Griffiths..

Chris - Now team 1, Jim and Jane, you may confer. This is “Marine Life or Marine Lie?” Do you see what we did there? These are things that you might or might not find at the seaside. So can you tell us which of these unfriendly sea creatures would you be most likely to encounter on the Ningaloo Reef in Western Australia? a Frumoius Bandersnatch or a tasselled wobbegong? What do you think? Please confer.

Jim - I have no idea. I like the idea of the tasseled, some of these tropical fish have tasselly tails. 

Jane - Happy to go with that.

Chris - Okay. So you're going with the tasselled wobbegong?

A: A tasselled wobbegong.
It's a type of carpet shark. a Bandersnatch is in fact a mythical creature which was made up by Lewis Carroll in the Jabberwocky in 1937.

Chris - Very well done. Right team 2, which is of course Laurence and Howard which of these two would be most likely to pose in your photograph? A Wunderpus photogenicus or a Thaumoctopus fabulus? which of the two would be more likely to appear in your photograph and pose for you?

Laurence - I'm not sure I'd probably go for the first one that sounds a bit more...

Howard - It sounds a bit more scientific

Laurence - ...sounds a bit more scientific. We think that’s got a scientific feel about it.

Chris - You like the name?

A: Wunderpus photogenicus.
It is wonderpus photogenicus, the clue is in name. It’s a spotty octopus living in the water around Bali, it gets its name because the pattern of spots on each octopus is unique. And here's the science bit: Much like fingerprints, it means that these octopodes can be monitored in the wild through people photographing them. Thaumoctopus fabulus is in fact made up.

So it's level pegging at the moment right, everything to play for, back to team 1, who are Jane and Jim. “Travel in style, The ultimate holiday accessory” is round two. Does this cool holiday accessory actually exist? True or false. The USB air conditioned shirt Jim and Jane.

Jane - Don't see why it shouldn't.

Jim - There is a lot of talk about embedding electronics into clothing so I probably assume that's something you plug the shirt in
Jane - You can certainly attach a fan. Even if you’re low-tech.

Jim - I'm just not quite sure how the air conditioning would work though. What bit of magic in there, having plugged it in? Say okay what do you think?

Jane - Go for it. yes.

Chris -
    A: True
It's true, all you need is a laptop to charge up your shirt which keeps you cool on your sweltering hikes or off in the airport where there’s no air conditioning. Should your air condition shirt power out, you can run it on batteries as well. Isn't that nice?

Right team two, here we go. This is back to Laurence and Howard. What about a pair of money finding, metal detecting sandals? Real or something we made up earlier?

Laurence - I can't imagine there's a market for metal detecting sandals, is there?

Howard - Not really, there may be some quite quaint willingness to wear them I'm sure if they were. Maybe it's a marketing opportunity we should think about, what do think?

Laurence - Perhaps it is

Howard - But I'm not convinced that one could probably get one off some marketing Electronics site let's say.

Chris - So Howard is not convinced.

Laurence - I say false.

Chris -
    A: True
I'm afraid actually this is a real phenomenon. Actually there’s a battery pack which straps onto your ankle and then down to these flip flops or thongs, if you’re Australian. This actually makes it look like you’ve been tagged by the police. Would you like to see a picture of one, just here in the studio, what this wonderful invention looks? I’ve a printed out picture, you can see that’s a pair of sandley things and then you've got this wire coming out the back which goes up to this thing wrapped around your leg with a black box about the size of a TV remote control and some lights and LEDs, so it does look like you've been tagged because you’ve got an ASBO or something. But you can in fact detect metal with your footwear, but it's good for beachcombers apparently they can pick up coins on the beach that's obviously their sandals can detect. I bet they're worth their weight in gold. Make a fortune.

Round three. “Destination Unknown,” which of these is a dud or a dream destination? Jim and Jane which one actually exists; Disaster Café in Spain where they simulate a massive earthquake every night while you dine, or Hot Plate Iceland where they cook the food on heat from a volcano.

Jane - I should think the volcano must be real in Iceland.

Jim - Yes the Iceland one.

Jane - Going for Iceland.

Chris - I’m afraid, actually Disaster Café in Spain is the correct one.

A: Disaster Café in Spain.
Normally people are terrified of earthquakes but at Disaster Café which is at Lloret de Mar, people actually pay to experience a simulated 7.8 on the Richter scale quake while they attempt to enjoy their meal.

You didn’t get that one right so you're still in with a chance Howard and Laurence, here we go. Which bar is a real one? The underground bar in London where a bar on a train travels around a disused underground route, or the Jumbo Stay in Stockholm. This hostel and bar is inside an old jumbo jet. It’s open 24/7 rather than 747. It's outside the Stockholm Arlanda airport. What do you think

Laurence - What do you reckon Howard?

Howard - Well there was some talk of opening up the old Royal Mail Line wasn't there? And maybe there is a bar that zooms around the London Underground.

Laurence - I, kind of, think that if that was open, that I'd have known somebody would have gone there and told me how great it was.

Chris - But it might be rubbish. We didn’t say it was any good.

Howard - But then again the bar outside Stockholm is going to be hugely expensive.

Laurence - I got it wrong last time.

Howard - He wants to go to a bar in Stockholm, so let’s say that.

Chris -  Stockholm one is correct.

    A: Jumbo Stay in Stockholm.
The underground bar is one we actually made up the Stockholm bar is the Jumbo Stay. The rooms are about six metres square, three metres floor to ceiling and you can also walk out on the left wing. It's been turned into a fetching observation deck.

So there you go.

Weather forecast

How do you forecast the weather?

Chris put this question to meteorologist Jim Bacon...

Jim - I think the easiest way to describe what happens in the modern meteorologists office would be that most of us will be looking at the output from the mathematical models of the atmosphere and using raw data coming in to represent a starting condition. You can then use the equations of the atmosphere - how the the air moves how it exchanges energy, how it exchanges temperature, moisture and so on. Those parameters can be represented with equations in the model and it will predict what those numbers look like in a short time step ahead. And if you keep leapfrogging those far enough into the future you can get an idea of what the temperature field display would look like in six hours time. And models now - I used to work as a programmer in the Met Office at Bracknell and this was in the 70s before we all had computers at home and the models would split the atmosphere all over the globe up into -  it's a bit like imagine an onion with several different layers and on that onion there are lines that cross like latitude and longitude lines and each of those grid points represents a data value. And in those days the computing power was so limited that the data points were 150 kilometers apart and there were 10 onion skins in this model that represented the real virtual weather. So what happened is that as computers got quicker and more able, we now have models that have data points 4 kilometres apart used regularly to drive your TV graphics for example and a lot of aviation meteorology, in some specialist cases they’re 1 kilometre apart. They don’t have 10 onion skins if you like. They have 90. So they're much better able to represent the real physics of the atmosphere. So forecasts have become much better and you can move them farther ahead in time and still get a good result.

Chris - So when you say there is a model, basically people like yourself have written computer programs that know what the atmosphere does and they put some energy in and how it's going to move, how the air masses are going to move and how their energy is going to change the behavior of that patch of the earth's surface. And so we know from experience but also from modeling how it's likely to play out how that's going to move around and therefore what it's going to do to weather patterns and systems around the world.

Jim - That's essentially it. And the interesting follow on from that actually which is probably far more significant in importance, is that when you've tuned your models to be successful in the short term, you know pretty well that the physics is working reasonably well. They're still not powerful enough to represent individual shower clouds accurately but they can get them in a sort of parameterised way but nonetheless the interesting point is that once you know they work, what's to stop you running it not for next week or the week after, but running it for next year, the year after that and the year after that and so on? So you run these models for a model world's worth of 30 years data and see if the average temperatures that you calculate match the average temperatures that we have in our current climate. So you've calibrated the model to represent what we have now and then you can play God and do all the things that climate change people are interested in, which is you can chop down the Amazon rainforest you can irrigate the deserts, you can melt the polar ice caps and you can run the models again and see how those values change. Now you won't be able to represent it exactly but you give the scale of direction of where it will go. And it's the refining of those models that gives people the various answers about what climate change might look like in 100 years time.

Freckled face

36:05 - Why do I get freckles in the sun?

What causes freckles to come out in the sunshine?

Why do I get freckles in the sun?

Chris put Jane Sterling on the spot, with this question about freckles...

Chris - Now talking of the weather we've got this question for you Jane, which Adam has sent in…

Adam -  Why does the sun bring out freckles?

Chris - So what is a freckle and why does it make Adam go freckly, or anyone in fact?

Jane - So I’m detecting a little bit of an Irish accent with Adam there, and it may be that if he's from Ireland, has seen a lot of people with freckles because they are much more common in people with red hair or reddish hair, and particularly from the Celtic races that have moved to the British Isles many many years ago.

So a freckle is a little patch of skin where the melanocytes, that's the cells that make the pigment in the skin the melanin, they're a little bit more efficient at changing the effects of the ultraviolet light to produce more melanin. So between the freckles obviously, is much paler skin that'll tend to burn more easily. So in those areas of skin the melanocytes just don’t make as much pigment and as efficiently. If you got very dark skin then your melanocytes sites are very very efficient at making the pigment and obviously the skin looks darker with or without sun.

Chris - Does that mean that if you then retreat from the Sun or when winter comes, same thing pretty much isn't it, certainly in high latitudes like where we are, that your skin then regresses to a non-freckled state. freckles are not permanent?

Jane - You can usually see the freckles even if you never go out in the sun or at the end of winter but they become much more marked once spring and summer comes because those freckly bits, the darker bits, start making more pigment and the bits in-between don’t.

Forest ferns

How dangerous are ticks?

Chris asked GP Laurence about the best way of getting rid of tricky ticks...

Laurence - There are several different types of ticks. They're all parts of the spider family, the arachnids. In the UK we mostly have hard-bodied ticks. So these are little creatures that tend to live in long grass and in bracken if you’re walking through forested areas if you’re going walking through there, they can climb onto your skin and they don’t fly or they don’t leap as some people think. And then once they are on your skin they burrow in  little mouthparts that they insert under the skin and they actually secrete a little cement type substance within their saliva to really root themselves in quite firmly, and then once they are in there they can feed for certainly hours, sometimes for days. So I think the key thing with ticks is actually a lot of the disease transmission that occurs with them comes towards the end of the feed and so the priority really is getting them off quickly. Again as with the jellyfish there’s lots of stories of methods that aren’t really valid so smothering them in Vaseline, burning them off with a lighter, or all of these sorts of things - a)  I think they're likely to be hanging around on your skin for ages, or b) you're likely to give yourself a burn or a worse problem to be honest.

So the key thing is you want to get the tick out intact. So with some really fine tweezers get right to the base of it and try and pull it out with the mouthparts intact, so nice straight pulling motion not too much twisting because otherwise it'll break. You'll be left with the body the tick coming out and the mouthparts left in, so close to the skin fine tweezers, straight pull. You can actually buy devices, probably the best place to get them is a pet shop or a veterinary surgeon’s that are designed to do this. The other thing never to do is don’t squeeze the body of the tick because all you are doing there is squeezing all of the saliva all of the blood from previous hosts with all of these infections and is going to go straight in and that's the worst thing you want to do.

Chris - What sorts of things should people look out for if they find that they have been bitten by a tick? What should they be aware of?

Laurence - So I guess it also depends where abouts in the world you are. There are literally hundreds of tick borne diseases. In the UK particularly in East Anglia, the most common one is Lyme's disease. After infection there can be a period of several days sometimes several weeks, and then you can typically develop this rash that looks a bit like a bullseye around the sides of the bite. That then generally fades and actually if it's not treated at that stage it can go on to cause more disseminated problems that can cause joint pains and joint aches. It can rarely cause neurological problems so you can stop working you could end up with numbness or weakness in areas, it can even affect the heart. So it is quite a serious condition. The good thing is if you detected early you can treat it very effectively with simple oral antibiotics. So I think that the thing to do if you've had a tick bite. We wouldn't need to treat every tick bite because actually this transmission doesn't occur particularly often but if you have a tick bite and then you get a rash you just need to go into your GP and treat this.

Why does the sea feel warmer at night?

Chris Smith put this coastal question to Weather Quest's Jim Bacon...

Jim - I would say, strictly speaking, there's quite often no difference at all in the sea temperature. Water is very good at spreading energy through great volume, so sea temperatures when you look at the deep ocean temperatures or say the North Sea or the English Channel they might be within point five of a degree for days at a time. So you won't get a diurnal change. I think we should be more talking about what the beach is like because one of the things about being at the seaside of course is that most beaches that are popular are sand and sand is very good at retaining the energy from the sun doing the day in the top few millimeters of sand grains and sand grains also have big air gaps between them so that's a good insulator. So it's very hard for energy from sunlight to penetrate deep into sand. So you know from your holidays in any sort of climate but particularly heat waves like the one we're having in the British Isles this summer you walk on a sandy beach and it's really hot to your bare feet and sandy soils are particularly good at gaining heat quickly and losing heat quickly.

So, let's say for example your going to the seaside at dawn, you've got out of your tent pulled back the door and you think yes let's go and have a swim before breakfast. The sandy beach will have cooled overnight so it'll be at its lowest temperature. You go into the sea and your feet are cold and it feels quite chilly. But let's say the tide is not in yet but when the tide comes in across the cold it's just coming in comes in across the cold sand it's not warmed up. You compare that to the second half of the day when you've had the whole day's sunshine heating the sand and the tide comes in over. It's like moving it in over a hotplate. So the water, the shallow layer of water, that you’re splashing about in is immediately being warmed from below. And so you will feel warmer and actually it is warmer but the deep well-mixed water off-shore isn't changing much at all. So I think he's absolutely right with the observation

Chris - I did quite a bit of sailing in my youth on estuarine waters and used to find the water on the outgoing tide at the end of a day was a lot warmer because the tides come in over very very hot mudflats and absorbed all the energy from the mud exactly as you're saying Jim. And then when that water goes back out to sea again at the end of the tide it's a lot warmer.

Jim - It's something that happens particularly in some parts of the country where you have very very shallow estuaries like the wash in East Anglia is one and that affects temperatures of the land nearby. So there will be many places around the world where you have deltas and suchlike where you've got these shallow seas and the temperature on the land will be affected greatly by whether the tide is in or out and that can also affect weather when you get mist and fog from the sea rolling in shore, that warm that's given over the over the mudflats will determine whether the fog evaporates before it gets in land or not. And you can have a very different day at the seaside with the tide in or out.

Plane in flight

Why do I get travel sick?

Chris Smith put this question to GP Laurence Kemp...

Laurence - So this is all to do with the way your brain processes information from different senses. So we have our vestibular system, this is little semicircular canals of fluid that are part of the inner ear. And they’re what the body uses to sense movement. So when the head moves around, the fluid within these canals moves around and then we can detect that as movement. Now the brain then matches that up with information that's coming through from the visual sense as well: from the eyes. And we experience motion sickness when the two of them don’t marry up together. For example, if you’re driving in a car and youre looking out the windscreen at the front you’ve got the visual information coming in. Your vestibular system is feeling the direction you're going in the movements you're making and you’re less likely to feel travel sick under those circumstances. But if you're in a plane maybe with a bit of turbulence and you're trying to watch a movie on the screen in front of you, or you’re trying to read a book. The visual information that's coming in is that everything is static, there's no movement, but your vestibular system is telling you that things are moving and the brain doesn't like that.

Chris - So let me get this straight. There's a disagreement between what the brain thinks the eyes are telling it and what the ears are telling it. So logically it throws up to solve the problem. Why? That doesn't doesn't seem logical at all!

Laurence - Yeah I was trying to work this out myself. Essentially we didn't evolve as a species to be going in aeroplanes or going in boats at high speed. There's a vomit centre in the middle of the brain believe it or not. And when these mismatches occur the vomit centre gets stimulated the activity builds up and then it does rather rule the day. So I’m not sure there’s an evolutionary advantage to being really sick.

Chris - maybe it's a deterrent to to not do what you were doing that made you feel at that in the first place: dont do it again!

Laurence - But the interesting thing is as you do it more and more times your body habituates.

Chris - It gives in!

Laurence -  Your senses adapt to it so you know actually when you’ve been at sea or on a cruise boat for a few days you get your sea legs and you stop feeling the motion sickness

Chris - Have you ever had thing actually where you get, Erasmus Darwin who was Charles Darwin's uncle I think, first described it and said, he called it “mal de debarquement” because people who had been on the mail coach, he described it as, you know the stagecoach that drove the length and breadth of the country carrying mail around. When you get off that after a long giddy journey you would still sense this sense of movement in the absence of any movement and then people realised it’s the same with ships planes that kind of thing.

Laurence - Absolutely, it’s because your inner ear and your body's habituated to the fact that you’re moving and then the movement stops and essentially you have to habituate the other way there, that is the changed environment. And what makes it more interesting is that you know actually that because its a brain thing those other areas of the brain that feed into it as well. So people that regularly experience travel sickness, and my brother’s a prime example of this, he’s been travel sick you know I’ve childhood memories of him throwing up on you know every every roundabout on our holidays. You go on a plane with him now and he starts vomiting even before you’ve taxied onto the runway, so it’s psychological…

Chris - Don't’ travel with him!

Laurence - No no I try to avoid it to be honest, or at least be a good distance apart.

47:52 - Which plants are best for bees?

Are some plants good or bad for our bees?

Which plants are best for bees?

Chris Smith was all a buzz with this question for Cambridge Unviersity's Howard Griffiths...

Howard - Bees feed primarily on pollen which has lots of proteins and lots of all of the other components that are needed to feed the larvae and they also feed on nectar. So we heard about the pollen earlier which causes problems through causing hay fever but we also have lots of plants that have co-evolved with insects to produce beautiful flowers and attract insects which then spread the pollen and so those are the sorts of plants that you’d want to plant in your garden. You’d also want to plant some that are going to flower throughout the season early spring through the summer through autumn and just make sure you've got a continuous supply of pollen and nectar.

Chris - So Howard, those are the good guys. But flipping it around a bit then. Are there any things that are particularly bad for pollinators things that look great but they're nice and far but far from nice.
Howard - Well there are some early plants like ferns and conifers that again aren't very good for bees but there are some plants that actually have their own neurotoxins, and rhododendron that invasive plant that causes so much trouble in some of our forests and uplands actually has its own psychoactive neurotoxins called grayanotoxins. They have their very own Novichok which are able to poison, well, people who eat honey that has been made by the bees from rhododendron.

Chris -  So it doesn't poison the bees?

Howard - Some bees are able to tolerate it although it does affect some bees a little bit.

Chris - It seems a bit counterintuitive that plants should seek to poison their pollinators.

Howard - Well it's probably an accident, it's probably that the poison spread through all of the plant to stop animals grazing and also accidentally gets incorporated into the nectar.

49:39 - When should I check a mole?

When should I get a mark on my skin checked out? How do you know if there's a problem with it?

When should I check a mole?

Chris Smith put this question to dermatologist Jane Sterling…

Jane - That's a really important question, particularly this time of the year when people start wearing less clothes and noticing the marks on their body. So I guess we’re really worried about the possibility of could a mark be a skin cancer and they are happening at all ages. But they do get more common as the years go by. But if you've got a mole that looks different to the others and if it's changed then you should certainly get somebody to have a look at it. So, always better to have somebody who can have a close look at a dark patch on your skin, a mole that you think isn't like the rest or is changed. Don’t sit on it or ignore it. Always get it checked out.

Chris - And when you say it's chain how might it have changed.

Jane - Moles do change a little bit with life they sometimes get a bit more sticky out they sometimes changing colour but if you've got a flat mole that's grown and it's not grown with you like you know a child getting bigger, if it's grown and your other moles haven't grown in its diameter or it's got one side of it that's growing more than the rest then that should be a worrying sign.

Chris - And someone would in the first instance go and see their GP like Laurence

Jane - Yeah they'd go and see their GP like Laurence if it may not be a mole because there are other marks on the skin that are brown. So the GP could could certainly say it's in the worrying category or it's not. And then if there's any uncertainty about it they'll be sent into hospital for a second look.

Chris - Thank you Jane for that one and this is a very important topic isn't it because as we mentioned the rates of skin cancer have rocketed in the last 10 - 20 years. They're more than more than a hundred percent increase I think is the statistics.

Jane - I remember I remember when I was a young dermatologist we were all amazed when somebody presented with a melanoma and now it's a daily occurrence.

Why has my garden gone yellow?

Chris Smith asked Plant Ecologist Howard Griffiths, from Cambridge University, to shed some light on this question from Liz…

Howard - Sure. It's a question really of how grasses grow. Because you’ll all recognise that you can cut grasses regularly but you wouldn't take your lawnmower to your herbaceous border now would you? And that's because grasses grow from the base, their leaves expand up, and that's why you can keep cutting off the leaves normally and they'll regrow again from the base.

But they're also adapted to grow in drying conditions and they also store lots of reserves in their roots. Basically at the same time they'll be packing away reserves into their roots. And so when they get a really dry period, they dry up completely. But don’t worry you don’t need to water your lawn. Many of the colleges we see in Cambridge aren't watering their lawns because we know when the rains come back the grass will regrow from those reserves.

Chris - It does come back incredibly quickly as well doesn’t it? You look at this thing, it looks like a complete desert, it’s completely brown and just a sprinkling of water later. And within literally minutes it’s begun to come back to life.

Howard - Well I wouldn’t say minutes. There are some plants that are able to come back like that they’re called Resurrection Plants.

Chris - But they’re very much greener as soon as you dampen it...

Howard - They will regrow very quickly certainly.

How should you treat a jellyfish sting?

Chris Smith asked GP Laurence Kemp for an antidote to this stinging question from Eric

Laurence - I’ll try to be quick on this one. There’s a lot of myths about jellyfish stings, the first thing I'd say is that the old myth of urinating on a jellyfish sting is absolutely false.

Chris - Really?

Laurence - Yes, it’s out. Urea as a compound may have a beneficial effect but your urine isn't going to be concentrated enough for you to really have any benefit. So don’t urinate on it. The best thing to do is if you've got some vinegar like we all take that to the beach regularly but if you put something acidic, like vinegar, on it then that will help to stop any tentacles from releasing further venom.

You can’t put freshwater on it either because the jellyfish and the matter sites within the tentacles are very sensitive to the osmotic pressure of the fluid around them. Actually putting freshwater on there will stimulate more venom release.

Chris - So you have to have someone who is really dehydrated to pee on you?

Laurence -  I think you’d have to be really dehydrated for the peeing, seriously dehydrated. The best thing is to apply something acidic, like vinegar, or you can actually buy jellyfish sting sprays that you can put on. Failing that, the best thing is to wash it with salt water and then after you’ve done that you need to try and remove the tentacles. Either with some tweezers or failing that get your credit card out, scrape it down the skin, to try and remove them off and then wash in hot water after that. That's the basic advice.

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