The Size and Shape of Raindrops - Sixty Symbols

[@frasersteen]

That flour-raindrop experiment is beautifully simple. Definitely should be done in schools a lot more.

[@DackxJaniels]

I pity the fool who goes to school near death valley. 50 years old - still waiting to get their 2 grade science grade. They can't complete their raindrop lab.

[@Cythil]

@@DackxJaniels That might be actually why this simple experiment is almost never done in schools (It is somewhat likely that someone had tried it in a school setting.) The experiment is very weather depended so you need to prepare it for one of those rainy days. And I think having that prep work and then the experiment on standby is a bit more of a hassle then in worth. Though of course there plenty of places in the world that get rain pretty regular so it might be something worth doing then.

[@boltaurelius376]

@@Cythil The only place to do this experiment is next to a lit BBQ. Thats the only way to ensure it rains.

[@moistmayonese1205]

Fraser Steen Experiments might be interesting but they are not that efficient tools for learning. But they might spark interst. However, they interfere routine, which is the most important oart of learning.

[@1.4142]

Doesn't rain for 3-5 months in a row in the summer in the bay area.

[@XsavioR38]

These videos are like sitting down and having coffee with some extremely bright people , something everyone can benefit from. keep it up. '

[@ZeedijkMike]

I was actually having a cup of coffee while watching this video.

[@Gjorten]

@@ZeedijkMike ditto :)

[@devangliya7131]

Always great to see Prof. Merrifield!

[@borjadelarco6052]

I'm a Naval Architect. I've always been told at uni that the two resistances ships have to overcome are friction resistance and wave-induced resistance. Once or twice been told that wave-induced resistance was different from friction resistance because of surface tension... But never quite understood why and that's something this video addresses perfectly. Hydrogen bonds cause water molecules to stay together, and that gives rise to this potential energy on the very surface (or the boundary layer between two fluids, in this case, water and air). This channel is just one marvellous thing for all of the curious people who love science and don't really have someone to learn from or talk to about it. Froude was right and didn't even know why! PS: now friction resistance which encompasses tons of different resistances like pressure resistance, viscous resistance, viscous pressure resistance, etc is a whole world apart... *As Sir Horace Lamb would put it: **_I am an old man now, and when I die and go to heaven, there are two matters on which I hope for enlightenment. One is quantum electrodynamics and the other is the turbulent motion of fluids. About the former, I am really rather optimistic._*

[@ParkerUAS]

Having been a pilot for many years and flying through various inclement weather situations I have the following observations to bounce off the physicists. 1. There is time for the rain drip to cycle through the various sizes due to updrafts. A perfect example is a hail stone. It starts small and freezes at height, then falls and picks up water on the surface. It gets picked up again and refreeze. Like an onion it has layers and each layer is a trip through the storm. The stronger the storm, the more layers and larger of the hail. Therefore, if the storm is the same as a hail storm, but the water doesn't freeze, why wouldn't it still go through the cycle? 2. Flying through the mid level of nimbostratus is where I have hit what I would consider the largest raindrops I have seen. At those points it sometimes is like going through a sheet of water, there doesn't seen to be individual drops just a wall of water to punch through.

[@JoseAbell]

Guys! Can someone please address this? Sheets of water on the sky? I need a video.

[@fewwiggle]

@@JoseAbell I think that is more metaphorical -- the rain is so dense that it "feels" like a solid (especially if you are moving into it). I've experienced something like this in thunderstorms in the midwest where it is like being embedded in a waterfall.

[@obiwan8972]

Happy to see u back prof

[@cpt_nordbart]

Reminds me of Douglas Adams book.. I think it was"So Long and Thanks for the Fish"... With a truck driver who is constantly in rain. And has his own scale of different rain types.

[@emarsk77]

I love the relaxed chat vibe of this channel.

[@dockmeister8480]

My favorite weatherman is back!

[@Kyle-li8wi]

This is exactly the information I have been searching for most my life. I just did not know it. But now that I do, I am happy.

[@marksimpson2321]

Im so grateful to Brady and Professor Merrifield for making these clips. Interesting science!

[@AverageBrick]

Great video, really well paced as well!

[@KepaTairua]

I've been missing sixty symbols vids! Always love a Professor Mike vid as well.

[@Knooper]

Yesssss I missed you Sixy Symbols!

[@keynesonsteroids]

Interesting and the surface tension energy was well explained. Thank you for making this video!

[@Jesse__H]

that part really was well-explained.

[@IceMetalPunk]

I know! I'd never heard it explained that way before. Surface tension has always been something that I just took as given without thinking about "why does this exist?", but suddenly it makes so much sense.

[@Rubensgardens.Skogsmuseum]

So then you are clear about why some liquids have less surface tension than water?

[@michaelc2245]

Hi Brady, I would love to see some follow up videos with the professors. It could be interesting to hear how developments such as gravitational wave astronomy and just the passage of time may have modified previous statements / answers to your questions.

[@Jesse__H]

That was a really good explanation of surface tension, that makes a lot of sense.

[@Pendoza84]

Seems i am watching this channel for quite so time now. For the first time I notice the professor is turning old! I hope he stays well for a long time. I always love listening to his explanations. It makes it look so easy (until you do the math).

[@annegallagher8284]

Got a typo here at 1:52/11:40. ... med 0.16 - 0.32 cm ... large 0.14 - 0.36 cm. Just love watching your video.

[@sjorsschoenmakers3629]

Actually rain can form in a different way. The kind of rain that Mike described, where vapor is condensing on little particles, forming small drops, and those can bump into each other forming bigger drops (coalescence), takes many hours or even days to develop any rain. That is the sort of rainy day stuff, where a large cloud deck (stratus) is formed in a weather front for example. When you get a shower from a smaller cloud (cumulus) or a thunderstorm (cumulonimbus), rain develops in a different way. Water vapor condenses into tiny droplets at the base of the cloud and move to higher in the cloud due to convective motion. The temperature drops with the altitude and below about 12 degrees Celsius, ice crystals start forming. Water vapor (100% relative humidity) sublimates on the ice crystals, creating snow. As the ice crystals grow, the relative humidity drops, and therefore the water droplets evaporate and so the humidity stays high. The liquid water droplets "feed" the vapor that then sublimates into ice. When the ice crystals grow big enough they start to fall and get in warmer air at lower altitude where they melt into raindrops. Also on their way down they encounter a lot of droplets so they grow bigger due to coalescence. This process is way quicker and is the reason that a thunderstorm can develop rain in (much) less than an hour.

[@DANGJOS]

Fascinating! He should talk about the weather on other planets too. For example, he could talk about how raindrops of liquid methane on Titan would fall differently than on Earth.

[@beliot3077]

I wanna see that.

[@RasperHelpdesk]

With a thinner atmosphere I'd expect droplets could get far bigger before hitting the threshold that would trigger the splitting action.

[@martingrundy5475]

Would they not also fall faster though due to the thinner atmosphere? I wonder if one effect would cancel or partially tend to cancel out the effect of the other? Would be fascinating to see. Even if that is true, slightly larger droplets at a greater velocity would make for some effect.

[@DANGJOS]

@@martingrundy5475 The atmosphere is *not* thinner; it's actually *thicker.*

[@adamrenwick7234]

What about sulfuric acid raindrops on Venus? Different surface tension, different atmospheric pressure and different g value might mean there's enough time for multiple cycles of formation-disintegration…

[@xyz.ijk.]

Beyond beautiful. Thanks Brady.

[@diodata]

That was fun, thanks. Enjoyed the discussion of the early experiments. But there was some fascinating physics left out, such as how rain drops could collect/merge with other drops as it falls...depends on size (effective cross-section radius) of falling drop and target drop. What would be really cool is to discuss how ice crystals form and grow in cold clouds to generate snow. Much different process than the collision/coalescence process he described. I always enjoy the atmospheric phenomena discussions in Sixty Symbols!

[@BradyBoll]

Veritasium put out a fascinating video on period doubling, the Feigenbaum constant, and the practical effects in real life like population modeling. I couldn't help but think that falling raindrops fit into this phenomenon. If given enough time falling through atmosphere, would we see chaotic droplet splitting/recombining and witness period doubling?

[@claus4461]

I feel like rain drops in summer that go along with thunderstorms are much bigger than a few millimeters. Rain seems really diverse from my perspective at least, where you can either have a very tiny spray or very big blobs...

[@abdesakib4424]

I'm amazed by Brady's question. They are so precise

[@allenyordy6700]

Keep them coming please this is my fav channel on youtube more of prof ed copeland please

[@larryscott3982]

The stereotypical rain drop shape I guess comes from a dripping water tap.

[@LuisAldamiz]

It does.

[@LuisAldamiz]

@pjd412 Shouldn't low aerodynamic drag be a much flatter shape, shard-like? I don't think I can agree: practical aerodynamics is a very ancient subject manifesting in spears and arrows for example, which do not look at all like the stereotypical drop shape.

[@Triantalex]

??

[@clockworkkirlia7475]

Ahaha, brilliant! I'm really getting back into these science education videos now that my own education has hit a bit of a speed bump.

[@grapy83]

Great presentation and great explanation.

[@bellsTheorem1138]

It's amazing how you can still learn something new about something as common as raindrops.

[@urbaniv]

Just yesterday my son asked me about clouds and rains and ping... With almost perfect timing this great video pops up thx

[@michaelhollins1556]

Thanks for that explanation Prof Merrifield.

[@Nobe_Oddy]

That was FASCINATING! I NEVER would have guessed that when raindrops get too big they basically explode from the "rising" air flow!! That's soooooo COOL!!! -First time I watch a video = LIKED! -First time I liked a video = SUBSCRIBED!! I just CANNOT WAIT to explore the rest of your videos!!! Wo0T-W0oT!!

[@bonob0123]

i always wondered about the speed at which your car is travelling and the number of drops/amount of water which hits your windshield in the rain. I imagine there are difference in stopped , slow, faster relative to the speed of the falling rain, very fast when aerodynamics become significant, size/amount/speed of rain etc etc, some rich discussion there maybe.

[@MrEazyE357]

Wow! This was an exceptionally educational video. Well done!

[@slashusr]

I was surprised to hear no mention of the "shot tower" used in days past to manufacture musket balls/round shot. There is a beautiful example of one such in downtown Melbourne, under a dome forming part of a railway station cum shopping mall called Melbourne Central. Basically, it's just a tall tower made of brick from the top of which measured drops of molten lead were allowed to fall to a bed of sand. The height of the tower gave the molten lead time to form a ball and grow sufficiently cool as to retain that shape upon reaching the bottom.

[@dsonawan]

At 4:02, Professor Mike Merrifield says speck of dust will start the condensation. However, once condensed into water droplet, why don't all the water droplets become ice. It is really cold up there. Some articles state that the liquid is in supercooled state and hence in a liquid state and not frozen into ice. But if the condensation was first triggered by an impurity like speck of dust, then the liquid should not be in supercooled state. I have searched many articles and some are honest answers saying we really don't know how rain is formed

[@123amsterdan456]

More Mike Merrifield please!!

[@attedau6235]

I almost went to school at Newcastle just to see you. We really appreciate you

[@61rmd1]

Nice video. I worked on this topic long time ago; the Marshall-Palmer size distribution is out of time, because of the behaviour of the diagram near to zero. Many other size-distributions came out, I remember the beautiful papers of Ulrich, and many other physicists, in the 80' and 90's. Some multiparameter Gamma-distributions were born, which more or less adapted their shape to experimental data. But the big question which came from the Marshall-Palmer work, was: what's the relationship between Rainfall rate and the size of drops?

[@drahunter213]

7:50 You can do that yourself the easy way for me was keeping a mouth full of water then while at a great hight just open your mouth towards the ground and the water in your mouth will fall and there’s a high chance a single large water droplet will be present with a bunch of smaller ones around it but halfway down the large droplet will be whole but it’ll explode in midair creating lots of other droplets then it hits the ground lol I found that out and how water works like that when I was a teen lol thought it was cool because I never seen a droplet explode in midair like that

[@marshallemmett3313]

I'm in Southwest Florida, USA and one thing I've noticed about storms is that the initial rain that falls is much bigger in size than the actual storm. It's not very intense with the big droplets, but it seems the individual droplets are bigger at the start of the storm the the main part of the storm.

[@PelycheeaceRA]

there are down-drafts at the edge of a thunderstorm. when the surrounding air is moving along with the drop, the air resistance is lower, so drops can grow bigger.

[@x4fab]

Great video, thank you! I was just thinking about making a shader for rain, making raindrops different in size for different types of weather would be a very neat little detail :)

[@AtlasReburdened]

I love that a few droplets from the top of the ballooning drop actually travel upward momentarily after the burst.

[@avinotion]

Merrifield is by far my favorite physics professor

[@savvapouroullis7927]

I didn't know it was my birthday today. Thanks for the 60 symbols vid!

[@Ritzoid]

Great video! Very informative

[@davidwilkie9551]

The quick version of the experiment is to play with the garden hose and put your thumb across the end, point the water up and look at the drops temporarily suspended in front of you. See how big and small they get in the time before hitting the ground. This video.., I've been thinking about for ages. Thank you.

[@CrepitusRex]

Another excellent video. Thank you kind sirs.

[@jaimie00]

I would love to hear his thoughts on dark lightning (AKA terrestrial gamma-ray flashes, AKA TGFs). There seem to be some complex processes at work to create the gamma rays. I love these videos. I wanted to be a meteorologist when I was a teenager. I chose zoology instead, but I'm still fascinated by meteorology.

[@leodikinis7390]

Always wondered how it works. Great stuff!!

[@DamianReloaded]

I guess there being wind would change things a bit. Also the atmospheric pressure. Like hail that forms in an upwards current until the wind can't hold it in the air anymore and then it falls down. Would a less dense atmosphere, or a lesser gravity, imply larger raindrops, or even streams of water?

[@rtpoe]

That something so commonplace would turn out to be so fascinating!

[@SaintJohnVideo]

Neat topic and followup questions, thank you!

[@NoHandleToSpeakOf]

How long does it take for a raindrop to fall? What is it's maximum velocity? How much kinetic energy is there in a drop?

[@darkiusdark5452]

I wish the professor would explain Nature phenomena the way Richard Feynman explained light and matter in his book “QED: The Strange Theory of Light and Matter”. That would be great and mind boggling! Thanks Brady and big thanks to the Professor.

[@forthrightgambitia1032]

Excellent video.

[@lawrencebutler7016]

so if rain brakes up as it falls why are the drops larger closer to the ground according to earlier in the video 3:47?

[@patrickmchargue7122]

The raindrop size experiment was great science!

[@Perun42]

Thank you! As always amazing!

[@brokentombot]

You forgot to mention if the common visual image of a raindrop is real or not. I am left to assume that raindrops are spheres and never go into that well down drop shape. I imagine a drop shape comes from when a portion leaves a larger portion and some adhesion occurs so a bit is drawn off slower and the sphere elongates. But does this mean water drops should always end up spherical?

[@superdau]

The "common" raindrop shape most likely comes from seeing something drip. Just before a drop falls from something wet, it looks "drop shaped". After that you would need special equipment to see the real shape.

[@Ryuuuuuk]

Without gravity raindrops should have a spherical form, because then it has the smallest surface area for a given volume.

[@12tman12]

They are actually flattish at the bottom once they start falling, due to effects of the wind. There's some vids around. Funny thing I see it with my naked eyes living in a 30 story apt in the middle of the building. During a storm, the air that hits the building where I am has nowhere to go but up (as seen when I open the balcony door, and one to the hallway heh). So often the wind speed upwards = the falling speed and I get rain drops floating around the balcony almost perfectly suspended in air. In snowstorms it's often I see nothing but upwards snow if there's a north wind.

[@nicolasamper7911]

3:37 how can the drops be bigger close to the ground if once threy break they dont reform again? And on top of that shouldnt the increase in air presure decrease the amount of water necesarry for the drop to burst?

[@Aaron_K]

Truly fascinating

[@aVoidPiOver2Rad]

Why does the NASA picture at 3:34 contratict the explaination he gives later in the video??

[@philippegirard6722]

You're right! It shows bigger drops at low altitudes. I demand an explanation, professor Merrifield!

[@aVoidPiOver2Rad]

@@philippegirard6722 Maybe the picture shows mostly the cloud and the splitting happens later OR these raindrops are just too tiny to split (drizzle)

[@sparhopper]

*Brady's reaction:* _"Huh..."_

[@jfdomega7938]

Fascinating!

[@WilliamDye-willdye]

A friend from north India said Monsoon raindrops can be extraordinarily large sometimes, causing pain if you were hit by them. I wonder if those raindrops formed at just the right altitude to hit the ground right before they would've split apart.

[@jackshumate7874]

Would love to hear a similar discussion of how interstellar hydrogen and ‘dust’ behave in star formation !

[@krzysztofsoja5301]

OK, Professor Mike Merrifield, You mentioned raindrops formation in updrafts, but what's happening with them when they get into a strong downdraft? That is an interesting case, istn't it? I suppose they can combine into huge ones due to downdraft lowering raindrops relative speed to the air.

[@AdrianAdrian-yo9lr]

So what would happen if you'd simulate rain in a big vacuum chamber? If there's no air resistance will the drops of water be larger, would they not balloon up?

[@Improbabilities]

In a vacuum, the drops would boil into vapor. Liquids usually don’t stay liquid without pressure.

[@Gts2pro]

Excellent, I have subscribed, wonder what I shall learn today !! I am doing my Physics higher education applied sciences 😄

[@Alienrookie]

It's 4 am (Austria), what am I doing here? Can't stop watching these videos!

[@peterway9376]

In a large storm there can be an enormous amount of up-draft. It is this up-draft that is responsible for hail stones growing to large size. Surely then it can have an effect on rain drop size.

[@der0hund]

Nice video, but what has to be mentioned as I think, is, that without hail there would be no rain. Coalescing clouddrops can only form very tiny droplets. Bigger raindrops were frozen before, and when they melt, they become raindrops. That's where all those interresting phenomena occur. - And sometimes the hailstone has no time to melt before hitting the ground. The story of raindrops is very interresting indeed, and full of wonders (one of which is the rainbow of course).

[@garyknight8616]

Great explanation. Just missing the brown paper for the diagrams (c.f. numberphile)

[@asudeaydin7985]

When you say he took drops of known size at 1:40, how exactly can one create drops of known sizes?

[@Toobula]

I want to do an experiment to answer this mystery: Why would video like this have 21 dislikes? The title is clear and it is from a well-known (and terrific) producer. Nobody is here by accident and then got disappointed - I simply don't believe it. We've all seen this effect. My theory is that it is a stochastic result of random clicks on display screen, like the raindrops. That is, there are some number of random clicks on a screen happening all the time. Possibly bots "feeling" for clickable areas. Possibly clumsy people, maybe even disabled people, accidentally clicking or tapping randomly by accident. The result might then be the total number of random clicks divided by the percentage of the area covered by the "dislike" button. Of course, the random clicks would not be evenly spread around the screen. They would tend to be near other controls, near the center, and so forth. Science, we need you! Regardless, anyone who watched and then disliked this video, or any other of Brady's videos, is an idiot.

[@seanehle8323]

Seems like at least some of the shrapnel drops could be re-lifted to the upper deck of the cloud via updrafts... or is that really a niche phenomenon? I recall hearing that hail is formed when a storm has these strong updrafts that keep throwing a raindrop to the top of the cloud, where it freezes, then falls and wets again, to be re-lifted to re-freeze. This is how hail chunks the size of robin eggs or bigger are formed... or so I was told.

[@shannonchuprevich3021]

I think there may be a bit more happening when the droplets first form as spheres. Nature's not really choosing the shape it's reacting. Quantum gravity could be an occurrence of an outter pressure, if space was considered an object. This is a very good topic btw. One that highlights the entropy of a molecules, from quantum gravity(the energy stored from the sun) to the point of our general understanding of gravity kicking in.

[@litigioussociety4249]

Some of the water in a cloud is in liquid form, that's why we see them, so I'm curious as to what causes the water to start to fall out as rain? Clouds can pass over a large region before they start to condense as rain, is it just the cloud getting dirty from some saturated amount of "seeds"?

[@gavinriley5232]

It basically has to do with surface tension. The liquid water you mention is attached to small dust particles. As the liquid water further condenses, the surface tension keeping it held around the dust breaks and causes it to fall to earth.

[@PelycheeaceRA]

the drops need a certain size and therefore mass to be heavy enough to overcome air resistance.

[@Njald]

The solemn tone of the last segment made me think you were going to till us that Professor Merrifield had passed or something

[@SteveGouldinSpain]

Anecdotal evidence I know but I was in a summer storm in Spain twenty years ago and the rain came down like golf balls. It was a very hot day and about two hours afterwards it was so dry you would not have thought it had rained at all! I just remember seeing how big the raindrops were and the splat they made when hitting the pavement.

[@Fiyaaaahh]

@ProfMerrifield I understand the process of how rain forms, but can you explain why clouds do not continuously leak? There's a statistical(-ish) process behind water droplets and vapor merging into biggers drops before they start falling. Why do we see only rain showers and never sporadic single droplets falling from the sky? Statistically this should happen.

[@eliad6543]

Very cool! Is there a way to measure the sizes of raindrops the way that they come out of the cloud, before the shattering?

[@Xen2288]

Awesome video! Will we be seeing any more videos with Professor Ed?

[@artistphilb]

I would imagine that the downdraft that often occurs at a storm front might prevent the large drops from experiencing a ballooning effect, hence large heavy raindrops?

[@beachboardfan9544]

At what size will the surface tension of the water be too much for the aero to cause the parachute and subsequent breakup.

[@launch4]

So if large raindrops go kaboom on the way down, how do we occasionally get downpours where the individual drops are huge?

[@arasharfa]

my favorite youtube channel

[@deathsheadknight2137]

what about solar forcing of rain through ionization or particles?

[@dordokamaisu2966]

Mike is the best!!

[@oldcowbb]

thats the best explanation of surface tension

[@GronTheMighty]

Perfect timing for me; was re-watching the third matrix movie last night and couldn't help myself cringing a little at one of the final scenes where there's a slow-motion CGI shot of Neo's fist going through the rain, hitting Smith in the face, where the falling rain drops are shaped like long rods.. Of course by the movies own logic that can be explained by the matrix glitching out and losing som of the calculations that deal with surface tension and air resistance, but as far as realism goes it looked kind of comically bad to my now-older eyes :p

[@boboften9952]

There Is A Quote From Peter Brock An Australian Race Car Driver Who As A Kid Would Driver His Car At 55 Mph To Defeat / Deflect Rain Off The Front Window Screen Of The Car He Was Driving Because The Rain Was Hitting The Window Screen Faster Than What The Basic Window Wipers Would Move . Effectively He Was Driving Blindly Until He Reached 55 Mph . ( 55 Mph = 88.5 Kph )

[@ComiXDude]

so, if the drops break up to smaller pieces right away, what is the process that causes larger drops to reach the group (as in the nasa picture)

[@chaoslab]

So cool!

[@poo2uhaha]

I loved seeing the professor (no Brady :' ( ) at the university open days! It truly felt like meeting a celebrity of mine.

[@MyYTwatcher]

Being a good popularizator is maybe even harder than being a good scientist. Good job, dr Merrifield.

[@annegallagher8284]

In Australia we watch the government seeding our sky. Our raindrops are warm but huge and preceded by hailstones in mid summer. Thanks for info in this channel.