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  • Dan: We're on top of the Marina Bay Sands hotel in Singapore.

  • It has one of the highest rates of lightning strikes

  • in the world.

  • We're gonna be running Image Based Auto-Trigger.

  • It sounds like you're out of a job.

  • - ( lightning crackling ) - Go! Go! Go!

  • Gonna miss all the lightning.

  • Ah.

  • It was the first time I think

  • where I've managed to chill by the pool in the day, but then...

  • - Yeah. - ...been running around like a nutter in the evening.

  • It was tiring. The most relieving shoot I think we've ever had.

  • 'Cause there was the chance that we flew 20 hours across the world,

  • nothing happen, and then we had to come back.

  • Fully down to chance.

  • I mean, don't know what we would've done.

  • Should we just--

  • - Pub? Pub. - Pub.

  • The moment when we realized that the lightning was

  • on the other side of the hotel was a fun one.

  • Pegging it through the halls.

  • I hope no one was looking through the spyholes on the hotel doors.

  • Just seeing a bunch of crew legging it through the hallways.

  • And what would we do?

  • My shorts are falling down.

  • Lightning is gonna be striking on the Bay side.

  • Before we test out lightning on Dan,

  • - What? - We spoke to an expert called Professor Liew.

  • - What? - What?

  • Professor Liew, how are you doing?

  • - Oh, hi, I'm great. Dan, Dan, right? - Yeah.

  • - Hello. Gavin. - Yeah, right, yeah.

  • So we're trying to capture the lighting in super slow motion

  • because when you look at it with your eyes it just seems instant.

  • How fast does lightning actually move?

  • It'll be a real challenge for you

  • because you know the speed is actually very, very high.

  • There are two phases to the development of a lightning strike.

  • It starts from the cloud.

  • A lightning leader will descend.

  • The speed up there is about one tenth the velocity of light.

  • Now that is not the main lightning channel.

  • The main lightning channel actually develops

  • after contact from the down coming leader

  • with the ground and then there is this return stroke.

  • Which moves up from the ground to the cloud.

  • And the speed of propagation of that particular channel is even faster.

  • That travels at one third the velocity of light.

  • ( lightning crackling )

  • Okay, so we got a struggle to capture this.

  • Yeah, we really are.

  • How many volts in a lightning bolt?

  • Voltage varies from about 10 million to 100 million volts.

  • - 100 million volts. - That's a lot of voltage.

  • - Yeah. So-- - You could fry an egg.

  • I think probably.

  • So, I'm not planning on it,

  • but what's it like to get hit by lightning?

  • Wow. ( laughs )

  • I do not advise you to, you know,

  • stand out in the open and say, "I'm invincible."

  • You know, try to attract a lightning strike.

  • When the voltage impinges on a person

  • that will cause a current flow to the body

  • the amount of current

  • which flows depends on the resistance of the body.

  • But, you know, in reality, you know,

  • when the lightning stroke hits you directly, you know,

  • the chances of survival is extremely slim.

  • The temperature of a lightning channel

  • is about 30,000 degrees Kelvin or centigrade.

  • - 30,000-- - 30,000.

  • And how long is it 30,000?

  • Just for like a split second?

  • It is actually, you know, the whole duration

  • of the wave-- the lightning wave varies

  • from microseconds to milliseconds.

  • You know, the duration maximum may be about one second.

  • It could be fatal.

  • - Yeah. - So you'd know about it for sure.

  • What is the correct thing to do

  • if you're out in an open area

  • and there's a big lightning storm coming in?

  • - Well, you try your best to get indoors. - Okay.

  • - Just run inside. - Run inside.

  • He who plays and runs away

  • and lives to play another day, you know.

  • - ( both laugh ) - I like that.

  • Yeah, so, run indoors.

  • I think that's the most sensible advice.

  • - That's stupid. - Oh, come on.

  • Go, go, ask him.

  • So is it true, um,

  • you get superpowers when you're struck by lightning?

  • I wish that could be so, you know,

  • then I'll become Thor or Iron Man.

  • - Okay. - No.

  • - The answer is no. - No.

  • Oh, you mislead me for a second.

  • I was like, "Does he or what?"

  • - Okay, well thanks very much, Professor. - Okay.

  • - Thank you, Dan. - Thank you.

  • - Thank you very much. - Yeah.

  • Okay, back to you, Gav and Dan.

  • Thanks, us.

  • - I bloody loved him. - He was a legend.

  • - He reminded me of my granddad. - Yeah.

  • Time for a bit of analysis.

  • I wanna take one of our clips,

  • find where we can see the entire bolt

  • from cloud all the way to the ocean

  • and time how long it took for all the feelers to hit the ocean

  • - in real time. - I think it'll be fast.

  • I also think it will be fast.

  • Time code is set to zero point zero seconds.

  • - Yep. - Ready to time it?

  • Okay. Yes.

  • - Uh, that was it. So-- - ( laughs ) What?

  • If I go frame by frame

  • Here we go, yeah.

  • - What? - Yeah, yeah, yeah.

  • So one frame is traveling that far?

  • Point zero zero zero six seconds.

  • - Like I said, it's fast. - 632--

  • - It's so-- So, yeah. - Really fast.

  • What is interesting to me,

  • if you look at all these step leaders,

  • which is you know each finger of the thing.

  • They're all trying to find the path of least resistance

  • down to the planet,

  • but the one that gets there first

  • is the one that sends the bolt up.

  • But you can already see before it wins,

  • what the shape of the lightning bolt will be.

  • So when this hits the ground here.

  • The lightning will come up and follow the exact path that this one took.

  • - So that's the exact-- - And everything else disappears.

  • See, that's like the exact perfect angle.

  • It's a lot going on in just a lightning storm.

  • It is. It happens so quickly as well.

  • There's actually a clip I found

  • where it's sort of halfway coming up.

  • So, you mean to say that even though the speed of lightning

  • of it going back up, you managed to capture it

  • where it hadn't gone all the way up yet and it was literally only halfway up.

  • - Yeah, you wanna see it? - Yeah.

  • - See, look at that. - Whoa!

  • So that is sort of halfway

  • between the white out that we saw on the other one

  • but it hasn't reached this point.

  • So you can actually imagine it's not actually like this.

  • It's just so bright, it's blowing out the camera from that point.

  • And the thing is because of the camera that we used,

  • the 2512, has a global shutter.

  • That means this is an actual moment in time.

  • This isn't an artifact because of a rolling shutter.

  • This is actually how far up it got.

  • So if we'd have given it enough of tiny, tiny split second,

  • it would've been all the way to the top?

  • Yeah. Well, because in one 28,500th of a second,

  • it hit the ground and went all the way up to here.

  • Shall we do a lovely tabletop experiment?

  • Yeah.

  • You've forgotten what it was, didn't you?

  • That's good, that's good.

  • The Van de Graaff generator.

  • - Classic school experiment. - Yep.

  • I like the gloves more than anything.

  • Rubber gloves. How's it work?

  • The way this works is similar to lightning

  • in that a lot of brushes in here

  • build up a static charge.

  • Like friction and build up a charge.

  • The lighter positively charged particles come to the top.

  • With lightning what happens instead of brushes,

  • you get the warmer air going to the top and then cooling

  • creating ice particles that then come down

  • and they bash into each other and create a static charge.

  • So instead of brushes you've got ice,

  • and in the top of the cloud you got the lighter particles

  • and the bottom is the negative.

  • That explains why Singapore is such a hot spot.

  • It's because of the warm climate.

  • - Yeah, so the water-- - Warm water, warm air.

  • All goes to the top, through the clouds, forms the clouds,

  • ice in the top, brushes together, makes lightning.

  • - So this is ready to go. - Yeah.

  • We're gonna film it with the 2511,

  • very similar camera to what we used in Singapore.

  • We will have to dim the lights

  • because these flicker like crazy.

  • And also we wanna see the spark, not these lights.

  • That sounds good.

  • I'm kinda scared, but also excited.

  • - Let's turn on the loud beast. - Okay.

  • I feel like generic bad guy from famous movie.

  • Yeah, yeah. All right, so I'm gonna turn it on and power up, okay.

  • - So should we turn the lights off? - Yeah.

  • Oh, you can hear it.

  • Okay, I'm gonna just slowly move this closer and closer.

  • - Yeah. - Okay.

  • Here we go.

  • - Oh. - All right, stop.

  • Turn it off.

  • All right, you ready? Playback of slow-motion footage.

  • - Yep. - That's it.

  • That is one frame.

  • - One frame? - Well, it's 28,000 frames a second

  • over an inch?

  • I guess, uh,

  • because lightning is so much further away,

  • it's like miles high that we are getting much more of chance

  • - to see it. - Yeah.

  • So I feel like this video has been a lot of step leaders

  • leading down to one main point.

  • Yeah.

  • Which is you getting zapped by electricity.

  • I mean, blokes get hit by real lightning and survive.

  • So what's this little thing brushes and stuff really gonna do?

  • 395,000 volts.

  • - Is it? - Yeah.

  • But think about it like this.

  • ( laughs )

  • Lightning is a 100 million volts.

  • Okay, well, that makes me feel better then.

  • - Are you ready? - I guess.

  • All right let's get the lights in high-speed mode.

  • Okay. Here we go.

  • - ( groans ) - Was that it?

  • - Yeah, just-- - Oh, I didn't trigger.

  • ( laughs ) I was waiting for you.

  • - All right, let's just do it again. - All right.

  • - ( groans ) - ( laughs )

  • I was not expecting that.

  • I think you'd have to shoot in really close.

  • Oh, you just wanna go like-- ( groans )

  • - ( laughs ) - What was I expecting?

  • At least let me be filming.

  • - What was I expecting? - All right.

  • - All right, you ready? - I mean, yeah.

  • All right.

  • I'm just gonna go like--

  • ( groans ) ( bleep )!

  • ( laughs ) Ready?

  • - Yeah. - Okay.

  • - ( groans ) - Is that it?

  • I guess.

  • I can't see. Ow!

  • I can't see.

  • Stay away from this thing.

  • Why haven't I learned my lesson here?

  • I keep pointing at it.

  • What do I expect?

  • - Moron. - All right, so far

  • I've not seen a single spark on this.

  • Really?

  • 'Cause a finger isn't enough of a point.

  • All right, I'll try it with an elbow I guess.

  • Rolling.

  • Oh, I can feel it.

  • - My hair is like going towards it. - Yeah.

  • ( groans )

  • Bloody saw that one.

  • That was a bright one, wasn't it,?

  • - That was amazing. - Christ.

  • - All right, Dan, very good job, obviously. - Thank you. Yeah.

  • - You ready for your moment of glory? - Can't wait.

  • And when I say moment I mean a very--

  • it's a tiny fraction of a second.

  • - Oh, there it was. - That was it?

  • That was one frame. There it is.

  • Also, know the fact that it hits the ball

  • and then you see the reflection...

  • - Oh. - ...in the ball back to your mirrored elbow.

  • That's so weird. Imagine if it was a lot longer

  • and two inches thick.

  • - That's what lightning's like, ain't it? - Yeah.

  • - Your arm would be gone. - Oh, yeah.

  • - Yeah, it'd be gone. - You would be gone. You'd pop.

  • Yeah, that was fun.

  • Feeling all right, Dan?

  • - A bit tingly. - Little bit tingly.

  • - Yeah, my arm's a bit numb. - You look good.

  • I think we broke the monitor, too.

  • - There's lightning happening on that. - Yes.

  • Like it's been affected or something.

  • Everything's a bit "ooh" here.

  • So I feel like I learned a lot from that episode.

  • I-- The main thing I took away from that

  • is that essentially all that lightning is

  • is a giant ball of static. It's just huge.

  • On a massive scale.

  • It's like the biggest pair of socks on the world's carpet.

  • - Yes. - Hopefully, you enjoyed that video.

  • Feel free to check out other less shocking episodes of "Planet Slow Mo"

  • and we'll just be right here while you click something over there.

  • I feel like you should get shocked as well for this.

  • That's probably fair.

  • ( zapping )

Dan: We're on top of the Marina Bay Sands hotel in Singapore.

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慢動作的范德格拉夫發電機 (Van de Graaff Generator in Slow Motion)

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    林宜悉 發佈於 2021 年 01 月 14 日
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