Why flying through clouds feels so turbulent?

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Why flying through clouds feels so turbulent? - 12/17/2012 4:52 AM

Lnewqban

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During my last airliner flight, we felt a lot of turbulence while descending (in final approach) through an extensive and thick layer of white clouds.

First, I thought of the water in suspension; however, further research showed that the liquid water in a cloud is in very tiny water droplets, and each droplet is around 0.01mm in diameter.

What then makes the wings of a B-757 bend up and down so much in such conditions?

Thank experienced pilots for any explanation.

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RE: Why flying through clouds feels so turbulent? - 12/17/2012 6:54 AM 1 votes

Hossfly

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quote:

During my last airliner flight, we felt a lot of turbulence while descending (in final approach) through an extensive and thick layer of white clouds.

First, I thought of the water in suspension; however, further research showed that the liquid water in a cloud is in very tiny water droplets, and each droplet is around 0.01mm in diameter.

What then makes the wings of a B-757 bend up and down so much in such conditions?

Thank experienced pilots for any explanation.

Here you will need to check out Meterology for some real knowledge on all the things that cause turbulence in cumulus clouds. White clouds are usually cumulus except for High Altitude Sirrus clouds. Cumulus clouds can get dark as the moisture swirls, especially on the bottoms. Cumulus clouds result from the rise of warmer air which cools as it does so, and resulting in rolling air on a warming/cooling situation, which creates the turbulence. That results in turbulence which is very much so as the cloud structure attains the energy to result in Thunderstorms.

"Final Approach" ??? Most airline pilots have enough moxie to stay out of cumulus structure depending on the style/size/ moisture content etc.. Then there are those than don't. Computer cockpits have destroyed a lot of pilot skills that we old timers learned, especiaslly avoiding heavy cumulus & T-Storms.. Those of us that started in the military40+ years ago (58 for me) had to make do with the equipment on hand and it should now be mandatory to know something besides a computer.

Many large airplanes have a large amount of wing flex. My first knowledge of such was in the SAC B-47 (4 years). Wings could flex 27 feet. When I walked around the aircraft if the external wing tanks were full, the wing tip was at nose level. (5'8" me) After landing with no wing tank fuel, I could NOT stretch enough to touch the wing tip.
In the Douglas DC-8 the 2nd Officer (and the captain

) had to monitor fuel levels in the wing tanks (internal) to keep adequate fuel in the outboard tanks to keep
the outboard sections from flexing up beyond the structural limits. All civil airliners that have to keep wing fuel balances within certain restrictions to maintain lateral balance of the machine. Early on with the B-767, at least one airplane almost bought the farm out on the Atlantic ocean when the COMPUTER system screwed up. It was pumping fuel from a tank across centerline to another wing tank. The co-pilot kept advising the captain of the problem and the captain would not believe a computer could fail. Well it became serious to the D-As captain when the machine started to roll beyond the trim settings. I forget all the details but the system that allows fuel to overflow from a tank was doing just that. They made it to an airport and flamed out after clearing the runway. Pilots that depend totally on a computer system are super rated D-As folks. Some many years ago, Delta at DFW proved that entering a Thunder Storm on final approach was not a goood thing to do. Maybe all of today's pilots have forgotten that. I have a whole lot of stories, and my son, a retired USAF Lt. Col. C-5 Instructor Aircraft Commander, now with Cont. Airlines as a Co-pilot has a lot more.

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RE: Why flying through clouds feels so turbulent? - 12/17/2012 2:42 PM

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As Hossfly said, it actually has nothing to do with water droplets. It's the rising air that forms the clouds in the first place bumping the plane around. And the wings are designed to flex.....it actually puts less stress on the airframe. Yes, it's unnerving, but perfectly normal.

You should always feel some bumps when flying through clouds. The scale goes from thunderstorms on the worst side, to high cirrus clouds which have no bumps at all (they're just ice). Nobody flies through supercells; airplanes come apart that way.

HTH

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RE: Why flying through clouds feels so turbulent? - 12/17/2012 11:54 PM

Lnewqban

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Thank you both very much !

Magnificent post, Hossfly.

Is that convective action what keeps the droplets from falling down on us?

http://www.youtube.com/watch?feature=player_embedded&v=NiCSk1zxMEs

rs917, you just made me Google supercell:

http://en.wikipedia.org/wiki/Supercell

Has ice formation on wings anything to do with the collision of the leading edges (wings and tail) and those suspended water droplets?

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RE: Why flying through clouds feels so turbulent? - 12/18/2012 2:16 AM

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HF, ask your son if he knows a Broderdorf, my old instructor.

Hoss said it all to a 'T'.

Clouds are also a possible sign of lift, or instability. Glider pilots love clouds, they help to locate lift.

The wing bending is normal. Learjets with tip tanks, and other aircraft, have to monitor fuel loads and have a limit called 'zero-fuel weight', beyond which any weight has to be fuel in the wings. Lear actually refers to it as 'wing-bending limit', which says it clearly.

Not sure what you're referring to on water droplets. There is a 'large, super-cooled liquid droplet' phenomenon, where water is in liquid form despite being in conditions below freezing temps. It can produce clear ice which builds quick and is probably the most dangerous form of ice for aircraft.

Hossfly refers to supercells, which figure prominently in a book titled, 'Anvils of the Gods', by aviation historian Martin Caidin. A great read, about the early days of high-altitude and jet airline travel and the accidents that occurred. BTW, it's Mr. Caidin's JU-52 in the opening of the 1968 epic movie 'Battle of Britain'.

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RE: Why flying through clouds feels so turbulent? - 12/19/2012 3:00 AM

rs917

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quote:

ORIGINAL: Lnewqban
rs917, you just made me Google supercell:

http://en.wikipedia.org/wiki/Supercell

Has ice formation on wings anything to do with the collision of the leading edges (wings and tail) and those suspended water droplets?

Yes, you're on it. The collision of the wing with supercooled water droplets (liquid water below freezing) causes those droplets to accumulate as ice. Depending on the temperature of the water, you get rime ice or clear ice.

Yahoo Answers actually has a good explanation.. http://answers.yahoo.com/question/index?qid=20090219092301AAP6mWt

Sounds like you're interested in weather. If you are, spend a little time this winter reading some basic weather books and even some aviation weather books. It's fascinating stuff. At the very least, you'll have a better appreciation for what's going on, and an ability to predict to some degree what's going to happen. Plus, I've found I'm less frustrated with bad weather because it doesn't seem like just a random force anymore.

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RE: Why flying through clouds feels so turbulent? - 12/20/2012 2:30 PM

Lnewqban

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Again, thank you all very much.

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