Neil deGrasse Tyson Explains the Sounds of Weather

[Music] check hey welcome back to the explain the explainer zone oh i like it you like the explainer zone i think we that should be what we call it now the explainer zone the explainer zone it's like the twilight zone except when you leave you know what's going on that's right the zone there's like the red zone the end zone the twilight zone the okay yeah all right all right i like it the explainer zone we'll work on that so i got one for you how about acoustic effects in climactic phenomenon really yeah yeah i i just thought just thought about that okay it sounds um like something that if somebody said to me at a cocktail party i'd be like i gotta get a drink i'll be right back but they will come back because it's intriguing enough but they gotta get they gotta pray but first they gotta get prepped they're chemically prepped for it it's that all right so let's let's start out with um thunder and lightning for example so lightning in its path between the ground and the clouds or between a cloud and the cloud never goes in a straight line because it's finding the path of least resistance the entire time unknown to you this is what it's doing and then when you see the lightning strike it is already a predetermined path between one point and another all right now it turns out the sound of lightning is simply the shock wave of rapidly heated air by the bolt of electricity moving through the air which is extremely hot right okay it's thousands of degrees but what matters is that it is the air is some other temperature and then it is instantaneously made extremely hot this creates an expanding shock wave that we hear as thunder okay now because the because the path of the lightning is not straight there are kinks in the root so each segment of that kinky lightning has its own generated shockwave okay right so now you have multiple kinks generating their shock waves and you can have constructive and destructive interference of competing shockwaves that makes so much sense oh go ahead okay okay oh this is good okay so our researcher just found the the lightning 50 000 degrees 2000 degrees fahrenheit yes yes okay that that's hot okay all right so now watch so with these different segments that's why a single lightning bolt and by the way the lightning bolt is not all the same distance from you okay the parts that are a little closer that are on the ground if it's cloud to cloud the part directly above you is closer than farther away so the sound will hit you at different times but it's one generated event right so so that's why the lightning can go okay that's why it's not just one acoustic experience it is a it is a highly i love your thunder i okay you like my thunder we have to isolate i don't know what just happened you if i see that on a meme i'm going to come kick you oh my god i am so i'm going that is so going to be a meme so so here's the lightning and it's because of the acoustical configuration of the lightning bolt itself that is wonderful i'm serious that is so great because one of my favorite things in the world is to hear lightning i'm to hear thunder but not the rumbling thunder the thunder that sounds as if it is tearing the sky yeah because that it's okay i'm getting there that's my next point okay so so that so i'm just simply accounting for oh by the way constructive and destructive interference if you're not familiar with that so so sound travels in waves so it crests and troughs and that's this is a pressure wave through the air it hits your eardrum your eardrum vibrates we interpret that as sound so does your body too by the way there are certain frequencies of sound that are longer sorry there's certain wavelengths of sound that are longer than what will fit in your eardrum so your eardrum will have a hard time communicating it to your brain but the length of the wavelength is about the size of your chest cavity that's the low frequency long wavelength and so there are some sounds that you feel more than you hear that's the rhythm section of this if i heard lightning starting to do that it was like whoa there is a god and god is a dj so here's what happens the the lightning sound is a huge cacophony of frequencies of sound energy okay high frequency low frequency but here's the problem high frequency doesn't travel very far it's easily disrupted it's easily it can easily lose its energy relative to the energy that it started with and if high frequency sound loses its energy it becomes lower frequency sounds so the farther away you are from a lightning strike the lower is the total cacophony of frequencies that reach you so lightning on the horizon is [Music] right okay if you have a pet dog they'll they'll they hear that and they notice that and they might start trembling and you don't even know why because that frequency is below what you can hear the dogs hear it all right as the storm gets closer and closer the higher frequencies become more and more part of what you what you hear and if you hear a lightning strike where that sounds like it's ripping the fabric of the space-time continuum it meant it hits your house [Laughter] all right so so that's what's that's what's going on there sound moves through air at about 700 miles an hour plus or minus depends on the the density of the air but i like easy math so let's just declare that the sound is moving at 600 miles an hour okay 600 miles an hour is the speed of sound in air how far does sound go in a minute oh that's 600 divided by 60. so how far i don't know you can set up the verbal math problem [Laughter] i don't know 120 miles [Laughter] so if it's 600 miles an hour and you divide by 60 minutes right okay then sound will move 10 miles 10 miles 10 miles in a minute in a minute okay so sound moves 10 miles in a minute how many seconds does it take the sound to move one mile um 10 seconds or six six seconds right six seconds so it moves a mile every six seconds so that after a minute it moves it moves 10 miles and after an hour it moves 600 miles right so so basically if you want to know how far away the rain is from you time get the time difference between when you see a lightning strike and when you hear it so you see the flash and then you count one two count one mississippi two seven three so if it's five seconds let's say that's almost six seconds so the storm's about a mile away mile away yeah about a mile away and so and the real number is 700 miles an hour so it's you know you make a small adjustment but you get the basic idea okay sound moves a mile every six seconds and so just for your habits if and if you hear the thunder and it never gets closer than that the rain is not headed towards you don't worry about it go home go back to sleep but if if that time delay keeps getting shorter and shorter and shorter watch out watch out yeah yeah one last house hit you you're about to lose your house yeah dorothy you're not in kansas anymore there you go nice so a couple of other acoustic things so for example a snowflake is very very it's highly variegated right it's got six sides it's got a lot of texture and if you have snow that's descending and it's just softly landing on blankets on a surface okay now you have sound generally when you hear someone from a distance you are relying on the fact that the sound is bouncing off the pavement off the walls we don't think often about this but reflected sound is a big part of how we interact with our world around us all right if you have snow everywhere the surface of the snow is not rigid it's not highly reflective in fact it's highly absorbent so particularly for city people know this if all of a sudden the city gets quiet and you don't hear anything look out the window chances are it's snowing nice because the sound of the cars and all the normal sounds that reach you by reflecting off of steel and glass and concrete and cement is no longer reflecting it's all muffled yeah and so so the song the christmas song silent night holy night whatever other reasons you want to think of it as a silent night if it has just snowed guaranteed to be more silent than it otherwise would have ever been snow it's nature soundproofing nature soundproofing now when you're walking on snow okay as opposed to walking on sunshine okay so it's just snowed and you're walking on it okay and that will normally be a silent uh exercise okay because you're just pressing down snowflakes because they landed softly and now you're just sort of compressing them fine if it's colder i forgot the temperatures if it's colder than like 25 degrees 20 low 20s if it's definitely if it's in the teens or lower if you then step on the snow okay the snow says i will not yield under your boot print i'm going to hold my shape because it is cold enough that we are all solid and rigid and what happens the snow crunches yes then you crunch on snow so if you're filming a movie or if you're observing a scene and you hear people crunching on the snow guaranteed the temperatures in the low 20s are in the teens or there's a guy in a booth with some corn flakes and he's just matching the sound to the people walking i forgot the sound studios have all those sound effects in there right so so that's why snow crunches at cold temperatures and does not crunch at warmer temperatures by the way at the warmer temperatures your pressure is enough to melt the snow okay to bring it immediately below the freezing point that's a whole other star talk explainer that we've done what what ice will do under pressure under pressure yeah so these are interesting sort of sound things to look out for um when this happens now it has been rumored that aurora that you can hear aurora and and i don't i'm not convinced of that really yeah yeah because it happens that you know it's it happens 50 000 feet up you know 10 miles away and farther up in the atmosphere where the atmosphere is really thin right it is electrical so it could be that it's it's creating other electrical phenomena in your environment but to say that you heard sound that comes from that high i'm not convinced of that i don't believe but people say it so it's worth investigating it sings yeah yeah yeah it's worth investigating i think so yeah yeah and so let me think any other sounds you've heard in weather that you wonder about i mean you know aside from the fact that uh my uncle used to like to make his own sounds and then blame it on me [Laughter] while we were walking in the cold other than that now and here's another one um you know the sound of hail hitting right these are basically these are like marbles falling out of the sky i know what that sound is that is the sound of a call to the insurance adjustment yes so people think you know you know when do you get hail most you get it in the summertime right that's weird ice falling out of the sky in the summertime well it's a reminder that the sun is not heating the air the air is transparent to sunlight that's why you can see the sun from earth's surface through the air in los angeles los angeles and beijing and mexico city right so those are inversion layers that so they're climactically susceptible to trapping smog both those three areas you notice they're all in basins santiago chile as well so here's what happens the sun heats the ground the ground heats the air all right but if you go high above the ground it gets very very cold very very quickly no matter the time of year all right but in the summertime you have the most ground heating and so you have the most unstable air columns so the biggest thickest juiciest cumulonimbus clouds which you all learned about in elementary school the big puffy ones though you find those in the summertime and you look at them and you think the cloud is just sitting there but if you look for long enough you will see that it is roiling and in the roiling there is very highly unstable air rising within it the more unstable the air is in the upwardly rising columns the harder it is for whatever is hanging out in there to fall out of the cloud wow because it's kept buoyant by these upwardly moving air columns so so you so you first nucleate a little droplet of of ice it wants to fall out i say no you're not and it comes back out and it nucleates with more moisture because what is a cloud it's a big pocket of moisture okay so droplets water drops so it gathers more moisture and ah no you're not and it keeps doing this it keeps doing this until the frozen ball says you ain't holding me this time and that's why all of hail is about the same size because they had to it had to get to that size to overcome the highly unstable air columns that were supporting supporting it and so so so the the more turbulent is the air the the louder they will be when they hit the ground and then there it is and we always reference the size of hail to some other object which i find interesting no one says it was soft ball sized hair it was baseball sized hail i've never seen anybody talk about um hail sized golf balls right maybe it's obvious why but i don't know but anyhow so chuck that's a little bit of the sound of weather i love it so so very cool oh and one other thing one last thing you ever been driving a car and it's raining and it's raining you know the whole time you're driving yeah then you come under an overpass and it's silent yes okay just silent that's an interesting phenomenon because what your brain had done was create the sound of rain as the normal so that when you go under the underpass it's the absence of rain that you take notice of see and that happens in my everyday life where the normal sound is a houseful running around when you step out the house you say what was that when you step out into silence you wonder you look around so silent out here oh my god did we move to the country so there's a word i've seen and it hasn't caught on but i think it should it's the sound of the absence of rain under an overpass okay and it's called a down pause oh instead of a downpour yeah a down pause down pause there you go that's lovely i will leave you with that a little bit of what weather sounds like on star talk explainer the explainer zone thank you chuck ah it's a pleasure always good to have you uh we're out neil degrasse tyson keep looking up [Music] you

Channel: StarTalk

Views: 254,894

Keywords: startalk, star talk, startalk radio, neil degrasse tyson, neil tyson, science, space, astrophysics, astronomy, podcast, space podcast, science podcast, astronomy podcast, niel degrasse tyson, physics, chuck nice, sounds of weather, sounds of weather explained, weather explained, thunder and, thunder and lightning, snow, storm, downpause

Id: D47wzLYuRuI

Length: 18min 6sec (1086 seconds)

Published: Tue Jan 05 2021