# Clouds dont fall

1. ### H8wm4m

24
Clouds seem oblivious to Earth's gravity and show absolutely no tendency to fall to the ground. Yet they are comprised of water droplets many times the density of the surrounding atmosphere, and therefore defy the laws of floating bodies. It might be argued that the viscosity of the air and air resistance prevents them from falling. This could only slow the rate of their fall.
This phenomenon is usually explained away with the argument that "Brownian movements" are responsible. It has been detemined that unequal molecular bombardments at any instant on opposite sides of each particle produces the constant motion, allowing the clouds to remain.
This phenomena in itself creates he same enigma as the inability of clouds to fall. Over a period of time the bombardments working against gravity will actually be weaker than the bombardments working with it. The velocity of bombardment will be slowed by gravity.

Any thoughts?

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3. ### billiards

752
I would dispute that.

And if clouds don't fall, then what is rain?

4. ### Schrodinger's Dog

Fog is a cloud on the ground as well

5. ### H8wm4m

24
Why don't Brownian movements keep raindrops suspended?

Rain drops are usually 1 to 2 mm in diameter, and can be as large as 5 mm. Water vapor droplets are typically 0.01 mm in diameter, still exponentially larger than the surrounding air molecules. (Nitrogen, O2, Argon, etc)

What is meant by "This phenomena in itself (Brownian movement) creates he same enigma as the inability of clouds to fall" is:
The molecular bombardments working against gravity will be decelerated and the bombardments working with it will be accelerated. The difference between the average bombardment force working against gravity and average force working with gravity plus the gravitational pull on the droplet itself should not allow even the smallest droplet to remain effortlessly airborne. (Should the current belief of gravity be correct)

Water vapor droplets arent exaclty gaseous. They are not the same as the steam rising from boiling water. The average kinetic energy of steam molecules does not allow them to combine as Water vapor does.

You must ask yourself why gravity causes the raindrops to fall, and allows the water vapor droplets to remain suspended.
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6. ### Schrodinger's Dog

Yes that makes sense, but then fog forms when humidity levels exceed 100% and thus water vapour begins to overcome the forces acting against it as it condenses into water, water vapour droplets are water, water vapour is gas; I'm sure rain falls likewise when enough water accumulates.

Are you sure this is all that mysterious, I've not heard a theory that clouds shouldn't be able to float before? This sounds more like a physics question by the way. I'm sure if you could account for the forces then you would see why clouds don't fall, except in the cases mentioned, surely, or is science in the dark on this, because it sounds a bit far out? You might also want to consider heat energy. I'm sure if you consider the overall density of a medium you will see a denser medium always sinks.

I'm not an expert in meteorology so I'm kind of guessing but? Water vapour is the gas phase of water. if the vapour exceeds the saturation level of the medium or I think in rain Ice crystals form, it will either begin to condensate and then the cloud will either become fog or the ice crystals will seed themselves as they begin to fall, these ice crystals move up and down in the cloud by convection currents, becoming larger but eventually fall melting as they descend: et voila rain no?

Last edited: Jul 8, 2007
7. ### H8wm4m

24
Clouds of meteoric dust 50 miles above the Earth(and other planets) also show no tendency to fall to the ground. Air at that altitude is 1/100,00th as dense as it is at sea level.

Dont imagine there is nothing to investigate just because it is not being investigated.

In a strictly hypothetical sense, suppose this was seriously looked in to by the scientific community. If clouds were found to not conform to the laws of gravity, what do you, personally, think would happen? (in a broad sense)
...
It is much easier to ignore it and assume there is nothing more to know.
And believe me, clouds are not the only case (Dont ask)

Last edited: Jul 8, 2007
8. ### Schrodinger's Dog

Yes but don't forget that gravity 50 miles up is weaker acting on these particles by an inverse square.

$f(g)=k(g)\frac{m1m2}{r^2}$

f(g)=force of gravity
k(g)gravitational constant
m1,m2, relative masses
r^2 distance.

so it may not overcome the convection currents at these heights.

I'm not dismissing your claims arbitrarily let me assure you, but don't forget the onus is on you to prove that there is something mysterious going on, that is how science works.

If you could show me the physical data, ie the heat convection currents vs gravity at these high altitudes then maybe you could show there is a greater force acting on dust towards the Earth than to keep it moving up and down in the air currents. I'm all ears.

I imagine this has been investigated by meteorologists, and they have found nothing out of the ordinary, I could be wrong.

Last edited: Jul 8, 2007
9. ### H8wm4m

24
Thank you, Schrodinger's Dog, for being so open-minded and tolerant of my.. um.. talk. Frankly you suprised me.

I do realise the burden is on me, but I am sort of on my own since this isnt seen as a problem for the bulk of the scientific community. The info I find on the internet consists of vague mentions of Brownian movements, viscosity, and air currents; and I believe these have been refuted well enough.

I rely on mechanical models because my "relativistic" math is sort of ... lacking

As for the dust, I dont want to get into that just yet, let's stick to clouds.

Last edited: Jul 9, 2007
10. ### Gokul43201

11,141
Staff Emeritus
Actually, clouds do fall. The terminal velocity for a spherical water droplet of diameter of a few microns is smaller than a cm/s (it's slower for a nonspherical ice particle) - a typical cloud in still air will fall very, very, very slowly. Most clouds, however, are formed in updrafts of air, which keeps them up even longer.

Last edited: Jul 8, 2007
11. ### matthyaouw

1,216
It's a while sincie I've done any meteorology so I may not have this 100% right, but I remember learning that in many cases the bottom of a cloud represented the point at which net condensation occured, and below it, net evapouration. This would mean that if droplets fall below this level they soon end up as invisible vapour again, so the cloud base will appear stationary regardless of the movements of the individual droplets.

12. ### Schrodinger's Dog

A research paper on how clouds form in regions supersaturated with ice (high flying cirrus clouds) Also explains how they are regulated with thermal currents and gravitation. Bit highbrow, way beyond my level of meteorological study, but still it shows they have been studying the mechanisms and thermodynamics of clouds and do have some answers as to how they form and are kept aloft in the stratosphere. If you like I'll find some info about low flyers later.

http://www.atmos-chem-phys.net/3/1791/2003/acp-3-1791-2003.html

The pdf.

http://www.atmos-chem-phys.net/3/1791/2003/acp-3-1791-2003.pdf

Last edited: Jul 9, 2007