WHY is there a WHITE CLOUD? Explained by CAPTAIN JOE
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Don´t these videos of departing aircraft look ever so cool, as they hurtle down the runway, but why is there white smoke, fog or whatever you want to call it, within the engines?
What you see here, is actually a miniature cloud generating in front of the engine compressor.
So today I`ll be explaining how this cloud is generate in front of the engine via little experiment.
Here the related question:
I was on a commercial flight in a 737 stationary at idle on a taxiway. It had recently stopped raining so the relative humidity was likely near 100% and the air temperature was about "light jacket" level. I was in a window seat forward of the engine intake so I could see the whole intake.
Every 30 seconds or so a cloud would burst into existence across the entire jet intake and be sucked away in perhaps one quarter of a second. Was it really a tiny cloud that I was seeing and what bit of thermodynamics was causing it? Why was it periodic?
Thanks for watching, all the best your "Captain" Joe
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At 3:01, I think the statement is misleading. At the engine intake the temperature drops because the pressure drops, this is adiabatic cooling. But this is not the same effect that a desk fan uses to keep your body cool. A desk fan does not create a significant pressure drop. Instead it cools you through forced convection and the latent heat of vaporization of your sweat.
Janis M
Agree. Captain Joe’s comment confused me for a second. For a brief moment, up was down, right was wrong, and universal entropy decreased.
Then my simple monkey brain started trying to make critical thought. ¿If a fan magically made air cool, then why do we need air conditioning systems?
These all might happen one day, but not today.
To be more specific, all of his statements are wrong on this one... Looking at dew points read from a psychrometric chart is nonsense when we are not talking about constant pressure..
Spot on
He would have to get into the venturi effect for this so maybe he just glossed over it since that's extra complications
yeah, if we wanna be speciffic, a fan in an isolated room would actually increase temperature due to friction
The engine is actually a fan for the pilot because when it stops he starts sweating!
only when both of them stop
Good one..
MWB Gaming but one of them stops will still cause a bit of sweat
Over used joke
We had one of our KC-135 tankers, lose all four engines to low oil pressure, on a flight from England o the US. Pilot decided it was better to keep flying with engines with low oil pressure than with no engines. Nobody had serviced the engine oil, for several flights, and all four engines ran out of oil. They did an emergency landing at the first stateside base.
Amazing video Joeey! I wonder how you get to these specific topics. Very interesting and informative as always. :-) Enjoy flying and see you very soon!
I'm not even studying to become a pilot and I watch these regularly, you are incredibly good at explaining this stuff.
Thanks, appreciate your feedback :)
Me neither, I'm just interested in these things tangentially. Doesn't stop me getting ads from flight schools before pretty much every one of Joe's monetised videos...
@@rjfaber1991 "tangentially" you should be a pilot.
Damn, Joe is an international airline pilot but he still puts in the effort to make quality videos for us. There is a reason why he is the most popular in his field on CZcams after all😏.
Thanks Leonidas! Means a lot :)
Leonidas the plane is always flown by a pilot. Not CZcams commentators. Keep up the good work, Joe
Yes. But dont forget mentour.
justinl458 He is great too and I watch him regularly as well, but nobody can match Joe's quality.
Luqman.
Most of the time the plane is flown by the autopilot, the human pilot only puts the plane into manual control for take off and landing.
Accelerated air isn't cooler. However, faster flowing air passes more air against the warm surface and, consequently, takes on and evacuates more heat. To the skin, flowing air seems cooler ONLY because of the sweat evaporation off out skin and nerve endings detecting that heat energy gradient/evacuation as "coolness". I should add, since i forgot, that I was only referring to the part where Joe said "that's why fan feels cool". I most certainly wasn't trying to rewrite termodynamics laws! 😂
The direct effect of the pressure on the relative humidity is miniscule. But a change in pressure can result in a pretty high change in temperature and therefore a drop of the potential of the air to keep the water. 5° can make a big difference, especially at near 100% relative humidity.
So the cloud is primarily caused by the temperature change which is caused by the pressure change
I just wanted to say the same. The fan works as way that increases the airflow around the body which increases swat eavpoartion or as long as room temp. is smaller is your body temp it transports cooler air winch increases the heat flow.
tabaks Wrong. When a fluid is accelerated, its pressure will decrease. What happens thermodynamically to the fluid is very similar to an adiabatic expansion. The work of expansion is done at the expense of its internal energy. This results in a decrease of temperature.
It is not acceleration but adiabatic expansion caused by sucking air from the front of the engine
Marek Sygula Go check any text on fluid dynamics, any fluid that is accelerated will decrease its pressure. It's Bernoulli's principle. As air rushes through the inlet, it will accelerate and its pressure will decrease. This sudden decrease in pressure as the air is sucked into the engine can be looked at as an adiabatic expansion of sorts.
The air doesn't get cooler because it's "accelerated", and the fan analogy is completely wrong. The cooling and the acceleration are both the result of the pressure difference. As the air pressure drops, it results in "adiabatic cooling". Air gets hot when it is compressed, and cools when it expands, whether it is moving or not. When air is forced to flow through an abruptly narrowing orifice (such as in the bottle experiment) or abruptly deflects over a wing surface, the pressure can drop even further due to the Bernoulli effect. This results in even more cooling and fog. However, the Bernoulli effect is not a factor at the jet intakes because the cross-sectional area is relatively constant.
THANK you. I was confused when he talked about "moving air being cooler." Not so. Lowering pressure DOES cool the air, because there are fewer molecules banging into each other with lower pressure. So as the engine sucks in air, there is extremely low pressure as the air leaves the atmosphere and is pulled into the engine. That's when the air cannot hold as much moisture and therefore it condenses.
was looking at a airport stream on wet day and saw this effect. Being a Mech Eng myself, I thought about the reason behind and searched in youtube. Was shocked that Joe explained the reasoning like this and was trying to find a clear mind in the comment section. And there you are.
You explain stuff so well it’s almost impossible to not understand what you talk about. Great job, I hate when people make it more confusing but you don’t. I also subbed
2:57 "accelerated air is cooler otherwise a fan would lose all its purpose" - that's not true, it only transfers more heat off a surface, because slightly heated air is constantly replaced with non-heated air, but the air itself isn't cooler. Otherwise a hairdryer would lose all its purpose :)
For a normal fan (like the ones you have at home) this is true. But the fan of a turbofan engine deals with high speeds, so the pressure drops by a huge amount and that's why the air is significantly cooled. On the other side you have a high pressure zone, that's why the air is hotter.
Yeah, i was thinking the same. Maybe the explanation in this video is kinda flawed because the effect is not directly correlated to temp but only to pressure.
Great video, Joe, keep up the good work!
its the chem-trail liquid being sprayed in!
Everyone knows that!
(no not really)
As a Corrosion Engineer and mentor to new engineering students, I'm always looking for new techniques to explain thermodynamic principles and your description of Dew Point is excellent. Clear and simple to understand to those whom may find other explanations overwhelming. Excellent Captain. Please keep this form of visual description in your repertoire. 👍👍
Thank you for this Capt. Great information 👍
Good explanation Joe, I learn so much from your videos, thanks bro
Great video and fantastic demonstration!! Awesome!
This was amazing!! Thank you so much for explaining something that looked so magical into something that makes sense! great video!!
Hi sir, when u ll upload 3rd video on ILS?
Great Explanation! It's called "adiabatic expansion" (engine intake, above the wings, opening a bottle of soda water, ...) with a relative humidity below the dew point.
Thanks, got out of hand there :)
That's the best explanation of relative humidity I've ever heard. Thanks for sharing.
I have learned more from your videos than my teachers. They were awesome at explaining, so it is a great marker of your excelence in explaining. Love your vids!!
4:53 i got scared as hell listening on my headphones
Love aviation
Love your videos Captain Joe. Keep them coming.
I ... love ... your ... videos ... Joe! Excellent quality and so much knowledge that people in general do not know... Well done and keep’em coming...
Hi Joe!
Could you make a video about the headset you use?👍🏼
Coming soon :)
The air entertaining the engine is accelerating and losing pressure. The air can't hold as much water at a lower pressure and the water in the air condensates. This is similar to air passing over the top of the wing which creates a cloud as there is lower pressure there.
wrooong!
+entering!
*condenses
But, your science is sound.
Das ist tatsächlich sehr gut erklärt. Faszinierend, dass man das mit der Flasche so einfach simulieren kann. Daumen hoch und danke für dieses Video.
Extremely clear, my compliments
Joe, how do some pilots manage to land back to the airport when both engines get failure?
Hey Joe, I've got a question for you: why do Pilots start the right engine first, even when it's called engine 2?
Because for most airline aircraft, engine number two supplies bleed air to the air conditioning allowing the air con packs to supply conditioned air to the cabin And engine two supplies hydraulic pressure to the flight controls, I think.
This answered some of my doubts from school physics ! Merci beaucoup Monsieur !
Loved the video, extremely clear explanation, thanks for the info!
2:44 So can I use it to clean my house?
I thought the drop in temperature was due to the drop in pressure, not accelerating the air.
rmfleming69 Same thing. Moving air= less pressure. Less pressure = lower temperature
That's not how it was explained
Accelerating the air causes the pressure to drop
It's the venturi effect that doughtymquan is explaining. Joe probably didn't want to get into the depths of that since its a big concept lol
But Joe is correct in his brief form. If the air accelerates because of the venturi effect pressure drops which in turn cools
thanks for the video joe!
Great video as always Captain!!
5'000 cubic meter per second ! :O
Big Sucker :)
More like 500m3 at sea level and 15 degrees Celsius.
It's definitely not 5000 cubic meter per second. An Airbus A380 sucks 800 cubic meter per second which approximately has a weight of one ton.
@@flywithcaptainjoe I have found that The Trent XWB (A350 XWB), a larger engine developing 430 kN at takeoff, has an air mass flow of 1,440 kg/s. So it woild be around 1872 m3. Considering 2 engines, still less than 4000 m3. Am I correct?
You described it wrong: Wait wat? Minute 3: Faster air is cooler? Wtf??? Faster air FEELS cooler because of the layer of warmer air around our body....
The real explanaition why its getting colder is shortened:
The energy (in wich the molecules are moving) stays the same while the area (as a cause of the suction) ( less pressure ) increases so the temperature is going down.
(Examples: The mechanism how Refridgerators work / Why a spray of deodorant feels cold, even if the can was at room temerature )
I hope you correct your mistake (an easy to make mistake)
Because 4 a sience and physics nerd like me this is not the best part of your explanation🖒
Vincent Sooos he was talking about the wind chill effect of fans
Both explanations are true. a) more air moving around you will cause more temperature to dissipate (what you explained) b) moving air will drop its temperature due to the ideal gas law and pressure differences.
*for
...Yeah, the cooling effect in the front of these engines is basically the one form of cooling fans DON'T do. Fans cool down potential hot zones by circulating air around which averages out the temperature in the area, fans create a wind chill effect by cycling off the air around our skin that heats up, and fans evaporatively cool us if we're sweaty... Fans do _not_ change air pressure and adiabatically cool anything, sadly. That'd be a neat trick. (albeit loud.)
Fascinating as ever.Thanks
Ich liebe Deine Videos. Kurz und verständlich erklärt für den Laien. Weiter so.
Hi Co Pilot Joe..get that fourth strip
hahah thank you, i was freaking out looking in the comments that nobody else than me had noted that.
Major Tom captain Joe ain’t a Captain at all...change your name..don’t pretend your something you are not..psychological projection
I think 98.9% of his followers dont know what those yellow stripes mean. Otherwise there would be more comments noting that he is NOT a Captain and may never be, as it isnt just based on flight hours.
Major Tom yes sir I am familiar with the requirements..I’m a Captain..type rated on the B727, B757/767, DC10, A320, A330, B747, B744 with a little over 30,000 hours and will soon be typed on the A350
I like being taught physics and maths by joe
Mlgpenguinboy wait who’s joe
Mason MacIsaac the dude making this video
loved this video... great job!!!
This is the best explanation I've seen on this. My search is over. Thanks.
Captain Joe: Why is there a WHITE CLOUD
Me:because you are in the sky
Lol
So basically they vaping
Oh my, that's the funniest comment so far :)
Vape Naysh, y'all
November A.Jacks vape nation y'all
Captain Joe yes you replied that's a first thank you my evening got happier
loved it!! ur the best!!
Hello captain joe....love your videos.Just finished my medical examinations and passed my aptitude test :) your videos are the daily reminder for what's to come if i get through all this :D keep the videos coming :)) 👍
Can you listen to music while flying
i dont see why you couldnt play some music in one ear when the plane is stable, at its cruising altitude and ATC is not pestering you
IFR conditions in an engine lol
IFR is foggy 😉
Actually high water content does Impact the Power in a positive way. The more Mass flow the more propulsion. you can increase also the fuel flow as the Turbine gets cooling from an additional source.
Awesome explation with crystal clear understanding of concept. Thanks Capt Joe... You stand out from the rest
Good video Joe.
Love From Denmark
This much physics is normal for me.
is called thermodynamics. But first officer (not captain yet) Joe, didnt know that.
@@majortom4543 maybe he did but for many people if u say termodunamic they will be scared dont know why (at least its like that way in my coyntry)
Lethean, they get scared with the word Physics too. Its sad but thats what it is.
nice work Joe! Love it.
Hey man love your way of explaining complicated stuff and making it understandable
Also love your new intro
Keep it up!!!!
4:57 - lovers of flat Earth and chemtrails will not believe you. :D
physics is strange to them like aliens from Mars.
Eti had a little plane,
Little plane,
Little plane,
Eti had a little plane,
Whose surface was white as an airliner.
Bad jokes
That profile selfie tho ;)
Emir hates that little plane
Little plane
Little plane
Emir hates that little plane
Whose showers are somewhat insane ;-)
'Eti had a little plane' ? Can someone explain what Mentour is referring to
It's a nursery rhyme but using "Etihad" the airline as "Eti had"
Edit: I got it and I'm not even a pilot yet. Did anyone else not get that joke? I am curious for real.....
Lol! You can see yourself out. :)
Capt Joe has the best videos about aviation on CZcams. This video for example is more as a class of physics.
He knows how to make the most easy to understand comparisons about what he is talking about.
Congrats Capt Joe
Thanks for fueling my low key plane and flying admiration. Decent video!
First😂😂
Jim Chronakis nice
Second
Beautifully explained. This was an excellent explanation, thank you.
That's a beautiful tri-jet at the beginning of the video. Thanks for I'm including it. Great video, as per usual
Good video and lesson. Janis M has a good observation, which only adds to the overall description. Great job.
the best science explanation, i ever heard. so awesome!!!!
Loved it! That was really fun.
I really did enjoy this video, it's one of your best, keep up the great work.
Wieder mal sehr gut erklärt. Und zwar so, dass man es nachvollziehen kann. Solche Lehrer hätte ich mir damals in der Schule gewünscht.
Vielen Dank Joe und mach weiter so.
Another great explanation! Congratulations Capitan
Love you Captain Joe, you have all of the answers of my questions!!!
Awesome video! Thanks very much! Very impressive demonstration!
Simple ... Informarive ... Educational ... You are brilliant
This is a really good explanation of basic thermodynamics!
Great video and easy to understand! Thank you !
Very great video Joe! Thank you!
Wooow.. Congratulations great video Joe!!!!
Brilliant way to explain it.
Brilliant as always Captain Joe!
Loved this video!
Very nice demonstration.
It's also interesting to note that on humid/high air density days planes are noticeably louder.
Love it love it !!!!ceep up the good work
Fantastic work Joe...
My deep appreciation for this explanation. It is (ehr was) something I always wanted to know. Thank you very much for this video!
amazing video joe. You never fail to please! Keep it up dude
Captain you’re a genius! Awesome!
Great explanation and intro to Brilliant.
Great video! I just graduated from the army ATC course can’t wait to get out there and get some ratings
Cpt. Joe makes the best videos about airplanes and he explains the most as he can about everything that he talks about. Cpt. Joe, congrats for good videos.
Great explanation. Thanks.
Very cool demonstration. Excellent explanation. Really enjoy your videos.
Totally love you and your expatiation. I'm from Houston, TX. Meteorologists often talk of humidity, dew point etc. There is a lot of humidity down here. Keeps your skin from wrinkling. LOL I had a friend who flew for Delta Airlines. I once asked..."what happens when rain water is sucked into the engine?" He told me it's actually good for the engine. I didn't realize it was too HOT to flame out. LOL
3:01 Accelerated air is not cooler. Yes, faster air can evacuate or move heat faster, but it is not cooler, and the way a conventional house fan works is pushing air past you, evacuating body heat therefore making you feel colder.
Besides that, you did a great job explaining everything as always, Joe!
Fantastic explanation Cpt!
Thank you very much, I always wondered that and your explanation has been awesome!
Keep up! Greetings from Barcelona ✈️
All the videos you upload are really educating and fun to see and coordinating both your job and your CZcams channel makes you arguably the best one on this field
And that's why you are the popular as well🙄🙄🙄
best video joe....always wait for your new video
Very interesting, thanks for the lesson Captain...
Awesome video yet again Captain Joe! Thanks for all the hard work! :D
Deine Videos sind der Hammer Joe!!!!