Cable Forum - Snowflakes

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- - Snowflakes (https://www.cableforum.uk/board/showthread.php?t=33700444)

Quote:

Originally Posted by Hugh (Post 35767639)

Surely the composition of air/snow depends on the size of the snow crystal - they start off as tiny dendritic snow crystals, as they grow in size the become hexagonal, and as they get bigger, they become dendritic again....

I know, that's why I said 'if we assume your assumptions are correct' in my first post.

Cheers

GrimboAtCrimboUpNorth

Quote:

Originally Posted by GrimUpNorth (Post 35767642)

I know, that's why I said 'if we assume your assumptions are correct' in my first post.

Cheers

GrimboAtCrimboUpNorth

Ahhhh - I see....

I was assuming that your assumptions around his assumptions were well-founded, when in fact I should have been assuming otherwise, I presume?

Quote:

Originally Posted by GrimUpNorth (Post 35767627)

Think I'll use Mr North all the time from now on. I won't bother quoting our learned friend as I'm on ignore so won't get a response ;) but from my experience in life it's often the case that when someone feel the need to claim they are intelligent it's normally diametrically opposed to the reality!

The thing that astounds me is he wants a 'scientific' debate but I pointed out an error in a statement (quite politely for me I thought) and I end up being called Grimbo (quite like that one too - I could use that one at Christmas - Grimbo at Crimbo!!). I wonder what the response would have been if I'd have questioned the snowflakes are 50% air assumption?

Cheers

Mr North

Have you ever thought about opening a detective agency, then going into hiding and employing glamorous female ex-cops to do your legwork? Each week you could set them on the trail of some bad guy, after giving them their instructions via a beige squawkbox.

You could call them Grimbo's Bimbos.

Quote:

Originally Posted by GrimUpNorth (Post 35767627)

I love how anything he says can be hand waved away "I was assuming, or it was just fuzzy maths" yet anything said by anyone else gets treated with derision for the hint of the slightest mistake.

I mess up, all the time (Edit: Like there, apologies mods!), and I'll gladly accept when I do, because I'm a flawed human being and frankly, I am wrong more than I'm right, but bloody hell.

Quote:

Originally Posted by Wittmann (Post 35767579)

Now Grimbo, I resent your insulting personal remarks,which are quite unnecessary, so you are going on my Ignore list.

You're going to get a very big ignore list quite quickly if thats all it takes.

(btw, feel free to try and add me ;))

Quote:

Originally Posted by GrimUpNorth (Post 35767642)

I know, that's why I said 'if we assume your assumptions are correct' in my first post.

Cheers

GrimboAtCrimboUpNorth

You know what they say about assuming something :D

Quote:

Originally Posted by Paul M (Post 35767682)

You're going to get a very big ignore list quite quickly if thats all it takes.

(btw, feel free to try and add me ;))

Don't you need a secret code for that? :confused:

;)

Quote:

Originally Posted by Chris (Post 35767650)

:LOL:

Quote:

Originally Posted by Wittmann (Post 35767418)

I only meant to give some idea of weight, not aim to get a Nobel Prize.

Well I'm glad you're modest enough to admit you're not going to be winning a Nobel Prize with your posts.

---------- Post added at 13:58 ---------- Previous post was at 13:54 ----------

Quote:

Originally Posted by heero_yuy (Post 35767484)

Resolution and accuracy. Two entirely different things.;)

Precision and accuracy.

---------- Post added at 14:13 ---------- Previous post was at 13:58 ----------

Quote:

Originally Posted by Stop It (Post 35767538)

Everyone else has already went over the mass, but, the assumption that the mass of a snowflake would decide its descent velocity is flawed at best.

As you already said, snowflakes are complex things, but one constant is that they all generally fall at a gentle rate compared to hail and rain because they are less dense than these items. So, while large, the density of the snowflake should be comparable to a small one, so should fall at the same rate.

Not quite right. The density is not directly related to how fast it falls. The actual acceleration and terminal velocity of an object in freefall in Earth's atmosphere is directly related to it's weight (which we can safely assume to be directly proportional to mass) compared to it's drag coefficient (which we cannot safely assume is directly proportional to it's density).

Density, at best, is only approximately proportional to drag when considering simple, symmetrical shapes (e.g. a sphere). For anything even slightly more complex, e.g. a cube, drag will vary depending on which side or angle is facing down. Think of a sheet of paper falling vertically, vs. falling horizontally for example. When you get to the drag of complex objects with various sticking out bits there's additional factors to account for such as turbulence, vortexes, and separation. For something as complex as a 15" snowflake it'd be almost impossible to even approximate and could only really be determined accurately through direct measurement.

In any case, even the basic aerodynamics of a huge snowflake vs. a regular one are going to be so different that we can't say they will fall at the same rate, or even a vaguely similar rate.

---------- Post added at 14:21 ---------- Previous post was at 14:13 ----------

Quote:

Originally Posted by Wittmann (Post 35767545)

Do you really believe all that you have said ? Preposterous.

You are wrong in practically every word. You must have left school whilst in short pants to say things like that. How utterly ridiculous.

Same to you

Quote:

Originally Posted by Wittmann (Post 35767545)

Mass, shape and surface area determine drag.

Well you seem to have a basic, though incorrect grasp on physics. Congrats.

However mass has no effect whatsoever on drag, and shape and surface area can be approximately related to drag but not always.

Quote:

Originally Posted by Wittmann (Post 35767545)

Terminal velocity is proportional to mass

No it isn't.

Quote:

Originally Posted by Wittmann (Post 35767545)

If it weighed a ton, it would drop like a ton and make a huge crater in Mother Earth`s crust on impact.

Well, that's one thing you got roughly right. It'd make a crater, though not a huge one.

Quote:

Originally Posted by Wittmann (Post 35767545)

Come off it

You've said that so many times to so many people I'm not even sure what it means.

Have you never heard the oldie - "What falls faster, a pound of feathers or a pound of peas ?"[/QUOTE]

---------- Post added at 14:25 ---------- Previous post was at 14:21 ----------

Quote:

Originally Posted by Wittmann (Post 35767562)

Wrong again Grim. Sorry old chum, ya can`t win `em all.

The feathers/peas/mass comparison is not dropping these objects from 2,000 feet where air resistance looms up - called drag in the industry. It concerns dropping them from a few feet, where gravity is the only factor in the equation.

Wrong again Wittman, though in your case it seems you can't win anything.

Drag is a fully important factor when dropping an object from any height. Gravity is not the only factor at a few feet.

Quote:

Originally Posted by Wittmann (Post 35767545)

A feather with the same mass as a piece of lead as per your example, when dropped from a few feet will both hit the ground at exactly the same time on this very Planet we all love.

Do you really believe all that you have said ? Preposterous.

You are wrong in practically every word. You must have left school whilst in short pants to say things like that. How utterly ridiculous.

By your own reckoning, "What falls faster, a pound of feathers or a pound of peas" when dropped from a few feet?

---------- Post added at 14:25 ---------- Previous post was at 14:25 ----------

Quote:

Originally Posted by GrimUpNorth (Post 35767572)

I'd stop digging if I were you. I point out the flaw in your argument (that you're ignoring drag) then you ask if I've ever heard of a parachute - which despite your post above would be quite useful to have even for a fall from below 2000 feet.

Admit you're a good example of a little knowledge being a dangerous thing and there are many people out there (and on here by the looks of it) who seem to know a little bit more about a lot more things than you do.

:tu:

---------- Post added at 14:28 ---------- Previous post was at 14:25 ----------

Quote:

Originally Posted by Hugh (Post 35767639)

Surely exhibiting any actual knowledge of the subject matter at hand, even if only speculatively, will result in insults and ridicule from the OP?

Quote:

Originally Posted by qasdfdsaq (Post 35767805)

Well I'm glad you're modest enough to admit you're not going to be winning a Nobel Prize with your posts.

---------- Post added at 13:58 ---------- Previous post was at 13:54 ----------

Precision and accuracy.

---------- Post added at 14:13 ---------- Previous post was at 13:58 ----------

Not quite right. The density is not directly related to how fast it falls. The actual acceleration and terminal velocity of an object in freefall in Earth's atmosphere is directly related to it's weight (which we can safely assume to be directly proportional to mass) compared to it's drag coefficient (which we cannot safely assume is directly proportional to it's density).

Density, at best, is only approximately proportional to drag when considering simple, symmetrical shapes (e.g. a sphere). For anything even slightly more complex, e.g. a cube, drag will vary depending on which side or angle is facing down. Think of a sheet of paper falling vertically, vs. falling horizontally for example. When you get to the drag of complex objects with various sticking out bits there's additional factors to account for such as turbulence, vortexes, and separation. For something as complex as a 15" snowflake it'd be almost impossible to even approximate and could only really be determined accurately through direct measurement.

In any case, even the basic aerodynamics of a huge snowflake vs. a regular one are going to be so different that we can't say they will fall at the same rate, or even a vaguely similar rate.

Good points, and something I completely forgot to factor in, apologies. After all, feathers indeed fall in fits and starts as its shape means it catches the air at certain points more than others.

And yes, if such a snowflake was created, it would need direct observation to know just exactly how it would've fell. A quick search does say that larger snowflakes appear to fall more slowly in very cold weather as it acts like a parachute, but we can only speculate how a very large snowflake could fall.

This thread reminds me of this one bet it goes the same way to

http://www.cableforum.co.uk/board/26...e-feather.html

Oh the days when you could post as "Guest"...

Quote:

Originally Posted by qasdfdsaq (Post 35769364)

Oh the days when you could post as "Guest"...

It has never been possible here. "Guest" is what happens when you spit out your dummy and ask the team to delete your account. ;)

Thats why I can't remember when it actually was then :)

I'm not sure if the OP is a troll, certainly all the postings inevitably end up the same way, I don't know why he bothers trying to 'educate us' especially when he ends up being corrected on numerous points anyway.

I reckon within 3 months he'll have moved onto a new bridge.