00:00You're flying above Earth on the International Space Station at an altitude of 250 miles.
00:06You cast a glance out the porthole, and your eyes widen in surprise.
00:10There's some kind of bright blue flash just above nighttime Europe.
00:14It's like there was an explosion of some strange substance there.
00:18Such a strange luminous event was spotted by a French astronaut from aboard the ISS.
00:23And it wasn't an explosion at all.
00:25It was lightning, and was directed upwards.
00:29Until recently, this phenomenon was a kind of fairy tale among pilots.
00:34Scientists had heard their stories about lightning striking upward, and about red and blue flashes at high altitudes too.
00:41But there was no definitive proof of the existence of these luminous events.
00:45But they do exist, and are called sprites, elves, trolls, and ghosts.
00:51So how does ordinary lightning work?
00:53Masses of moist air in a cloud rub against each other and create static electricity.
00:58It would be almost the same if you danced in a wool sweater.
01:02It becomes charged with static electricity.
01:04And if you touch a metal doorknob, there's a discharge between your fingers and the door.
01:09There's your lightning.
01:10So a thundercloud builds up a strong negative charge.
01:14Sooner or later, a leader is born in the cloud.
01:17It's a bright thermo-ionized channel.
01:19Or more simply, lightning.
01:21The leader moves toward the ground in steps of a few tens of feet.
01:25And it can accelerate to an average speed of 200,000 miles per hour.
01:30At that speed, you could make a trip around the Earth in just seven minutes.
01:34But negative particles attract positive particles.
01:37And particles with opposite charges will tend to connect and compensate for each other.
01:41So, simultaneously with the negatively charged leader, the positive charge from the Earth begins its upward journey.
01:48The electric charge from the Earth connects with the negatively charged leader in one channel.
01:53This is when the brightest and loudest discharge happens.
01:56We call it lightning.
01:58It's this discharge that you hear as thunder.
02:01The main lightning doesn't strike from top to bottom, but from bottom to top.
02:05Yep, that is, the lightning is actually directed upward.
02:09It's as if the Earth is striking back at the thundercloud.
02:12And that charge can reach up to 30,000 amps.
02:16Your average wall outlet only has about 15 amps.
02:19And the record for the length of lightning is about 440 miles.
02:23That's more than the width of the state of Kansas.
02:26Meteorologists recorded such lightning in Brazil.
02:29It was a discharge between giant thunderclouds.
02:31And the longest lightning strike was recorded in Argentina.
02:34A single lightning strike there lasted 16.3 seconds.
02:39By comparison, you blink at 0.1 seconds.
02:43So we saw a regular lightning strike.
02:45The positive particles from the ground neutralize the negative particles in the cloud.
02:50But the cloud is still full of positively charged particles.
02:53They accumulate and wait for their time to create lightning.
02:57Once the charge reaches a critical point,
02:59the lightning cloud throws that charge dozens of miles upward.
03:02This is called a blue jet.
03:05It's exactly the same luminous event seen by a French astronaut aboard the International Space Station.
03:10The blue jets look like someone turned on a gas burner pointing upward.
03:15The positively charged blue jets neutralize at high altitudes with negatively charged particles.
03:20But people on the ground cannot observe blue jets.
03:23Thunderclouds obstruct the view.
03:25But they can be seen from an airplane.
03:27That's why, for a long time, commercial airline pilots were the only witnesses to this phenomenon.
03:33Onboard the ISS is also a great place to observe jets,
03:37as they are born at the very top of thick clouds and shoot dozens of miles upwards.
03:42But if you climb even higher, you can see this kind of bizarre lightning.
03:46It's a sprite.
03:47It looks more like a jellyfish, a cloud of red charge at the top,
03:51and a bunch of little tentacles coming down.
03:54Now, normal lightning can have a temperature of about 54,000 degrees Fahrenheit.
03:58But you can touch a sprite with your hands.
04:00Unless, of course, you're afraid of a powerful electrical discharge.
04:04The sprite has about the same temperature as an energy-saving light bulb.
04:08All because sprites are born in the mesosphere.
04:11This is the layer of our atmosphere that starts at about 31 miles high.
04:14And it's the coldest place on our planet.
04:17On the ground level, where we live, the air is much denser.
04:21There are just more air molecules.
04:23They absorb heat from the sun's rays.
04:25And we feel comfortable.
04:26But the higher up we go, the fewer air molecules there are.
04:30At the altitude at which commercial airline planes fly,
04:33there's no longer enough air to accumulate that heat.
04:36You wouldn't even be able to breathe up there.
04:38That's why every airplane has oxygen masks for emergencies.
04:42And the temperature here is even colder than at the South Pole.
04:46In the mesosphere, there's almost no air.
04:49And the temperature here can be around negative 202 degrees Fahrenheit.
04:53And although the temperature of the lightning itself is high,
04:56in general, it's like if you poured a glass of boiling water into a huge barrel of cold water.
05:01The temperature won't change much.
05:03Sprites can only appear when paired with thunderclouds below.
05:06As a discharge occurs in a cloud, a sprite appears in the mesosphere.
05:11It tries to equalize the amount of charge in the atmosphere.
05:14So it's like these red flashes of lightning are trying to reach down to the thunderstorm.
05:19And a sprite itself can be as wide as the state of Massachusetts.
05:24And then there's a ghost.
05:26It can appear for the tiniest fraction of a second right after the sprite.
05:31It's a faint green glow like an aurora.
05:33They were first discovered in 2014.
05:36And official confirmation by the scientific community only appeared in 2019.
05:41They're still poorly understood.
05:43But there's a hypothesis that ghosts have something in common with auroras.
05:47At least their color is green.
05:49And it may arise due to excited oxygen atoms.
05:53Sometimes we can spot trolls along with sprites.
05:56They look like pillars that support a sprite.
05:59It's a red glow at the end of the sprite's tentacles.
06:01The next moment, the troll releases a red streak down from itself.
06:07And if we climb even higher, we can see the elves.
06:10They only appear for one millisecond.
06:13It's a dim, flat glow that appears during thunderstorms in the ionosphere
06:17at an altitude of about 62 miles above sea level.
06:21Elves can be as wide as the distance between New York and Washington, D.C.
06:25Elves were first discovered during space shuttle flights in 1990.
06:29And these are pixies.
06:32They weren't discovered until 2000.
06:34Scientists observed bright, brief, luminous events for 20 minutes.
06:38Although they look like lightning striking inside a cloud, they have nothing to do with them.
06:43Pixies are smaller than 100 meters, which is about 330 feet.
06:47We shouldn't forget that any lightning is extremely dangerous for humans.
06:52And if you're caught in a severe thunderstorm, you need to leave its epicenter immediately.
06:56You can determine how far you are from the epicenter easily.
07:00The speed of light is much faster than the speed of sound.
07:03So, when lightning strikes, it takes a couple of seconds until you hear the thunder.
07:07So, you need to measure that interval.
07:10Lightning.
07:10Now count the seconds.
07:12Every second of thunder delay after lightning is about 1150 feet.
07:17That's the distance a wave of sound travels in one second.
07:20So, if the thunder delay after a lightning strike is 5 seconds, you're about 1 mile from the lightning.
07:25You can also tell if there will be a thunderstorm by the smell.
07:29The air before a thunderstorm seems unusually fresh.
07:32This is because the air currents bring in ozone molecules from the upper atmosphere.
07:38The same ozone protects us from harmful ultraviolet rays and transfers heat from the sun to the atmosphere.
07:44What we use to breathe is the oxygen of two atoms.
07:47Add one more and you get ozone.
07:50Ultraviolet light breaks down the two oxygen atoms and is absorbed by them.
07:54These broken atoms are then attached to the normal double oxygen atoms.
07:57When an ultraviolet beam strikes an ozone molecule, it knocks one oxygen atom out of the chain again.
08:04But ozone tends to regenerate.
08:06So, the lost oxygen is reattached to other double atoms.
08:10But the ozone layer began getting damaged when humanity started emitting harmful gas into the atmosphere.
08:16Freon is to blame.
08:18It's the gas we were using in old refrigerators.
08:21The freon molecule contains harmful chlorine atoms.
08:24Ultraviolet rays knock this atom out of the molecule.
08:27Then that chlorine atom steals one oxygen atom from ozone.
08:31And we have a double oxygen molecule that can't regenerate and save us from the harmful ultraviolet rays.
08:38This causes a hole to appear in the ozone layer.
08:41The most famous ozone hole was over Antarctica.
08:44But when humanity banned the use of harmful chemicals, this hole began to recover.
08:48It's not that the hole will close completely.
08:51It will just return to the way it was before.
Comments