Raindrop - tear drop or inner tube

1. Jul 28, 2004

woodysooner

I was reading a physic book the other day that said that rain drops were inner tube shaped and they showed a picture my advanced phys teacher said that is false because they are tear drop shaped and if you probe it. ie look for its shape, vel, pos. you will alter it that is why it looks like a inner tube then is because the walls can't hold the gravity or i dunno what he said but the thing about probing it is he talked Quantum on me and does that hold for something as large as a rain drop that once you define it or examine it it changes?

thanx

2. Jul 29, 2004

NO, the uncertanty principle only holds true for particles that are about smaller than the wavelength of light. A rain drop is way to large to have the uncertanty principle applied to it. If you do examine it in a vacum, without the friction, then you would see what it really looks like. I dont even think gravity has anything to do with the uncertanty principle.

3. Jul 29, 2004

Staff: Mentor

raindrops are not shaped like teardrops

The myth that raindrops are shaped like teardrops is so prevalent that there are web pages devoted to it! Here's one: http://www.ems.psu.edu/~fraser/Bad/BadRain.html

(And it's got nothing to do with quantum uncertainty! :grumpy: )

4. Jul 29, 2004

Njorl

That was truly interesting. Thanks.

Njorl

5. Jul 29, 2004

LURCH

I can't help but notice that the largest raindrop illustrated is shown as to teardrop shapes joined by a thin film of water, which according to the text will break, forming to smaller drops. These two, according to the illustration, are teardrop shaped.

6. Jul 29, 2004

Njorl

I think it is just showing a cross-section of rotation. It is not 2 teardrops joined by a film, it is a ring with a teardrop cross-section, and a half a bubble attached to it.

Njorl

7. Jul 29, 2004

Staff: Mentor

Read the caption off to the left:

8. Jul 29, 2004

Staff: Mentor

Very interesting - I've never thought abut it before despite having some aero classes. The highest pressure is of course at the stagnation point, dead center in the bottom of the (spherical) dropplet. Air moving around the sides doesn't push the sides in, it creates a low pressure, pulling the sides out. Thus the parachute.

9. Jul 29, 2004

woodysooner

so what is it?

so I am confused is it a tear drop, a hamburger bun shape, or an inner tube.

10. Jul 30, 2004

Staff: Mentor

Did you check the link I provided? Raindrops "evolve" from sphere to hamburger bun to inner tube--then break up back into spheres!

Seriously, the teardrop shape is a myth.

11. Jul 30, 2004

woodysooner

thanx

yayyyy. i was right then

12. Jul 30, 2004

that sounds like quantum uncertanty to me. Srry, I got confused, I thought he was telling you that the uncertanty principle applied.

13. Jul 31, 2004

woodysooner

that is what he said

My prof did say that quantum uncertainty applied but that can't be seen for things as large as rain droplets.

14. Jul 31, 2004

Mk

Yay! I know this one

Yay, I know this one:
Depending on the altitude and mass of the rain drops formed, they have varying shapes, fatter higher altitude raindrops are of the "doughnut" shape. Those formed those with less mass and lower altitude are of the classical raindrop shape. It might be vice versa though. I don't know what happens when smaller ones are formed higher and fatter ones are formed lower. I'll have to check my book, its in the garage somewhere.

15. Jul 31, 2004

Mk

Well, the point is both are true. The shape depends on the altitude in which they were formed.

16. Jul 31, 2004

woodysooner

thanx

thanx to all of you for your help