Clouds Falling Up

I was pondering Clouds and wondering “If they are droplets, why do folks talk about water VAPOR?” when I then pondered, if they are water droplets, why don’t they fall?

Found a very good page that explains why clouds don’t fall, so I’ll not try to re-write it. The short answer is “they do”. Rain, when droplets are very big, and “very slowly” when droplets are small. Sometimes, as very small droplets, they fall so slowly that upward air currents will carry them up faster than they fall. Then the clouds are “falling up”…

It all comes down to Stokes Law. Small stuff falls slower.

http://lamp.tu-graz.ac.at/~hadley/whydontcloudsfall.html

Skipping over the math part (that you can get at the link):

Clouds can hold an enormous amount of water. When this water falls as rain it clearly has a significant mass so why don’t clouds fall? In fact, the small water droplets that make up clouds do fall slowly. However, the drag force of the air dominates over the gravitational force for small particles. The drag force increases as the size of an object decreases. The force needed to move a sphere through a viscous medium is given by Stokes’s law,
[...]
A water droplet with a 10 nm radius falls at 12 nm/s in air. It would take 2.6 years for this droplet to fall one meter. It is only when the small droplets begin to coalesce into larger droplets that they fall with significant speed.

In some sense, the inverse effect to rain is the rising of bubbles in beer. Bubbles are lighter than the surrounding liquid so gravity pushes them up. They rise with a constant velocity which is described by Stokes law. If you are the type that carefully observes your beer, you will have noticed that sometimes the bubbles move down. This is because of the circulation of liquid in the beer glass. The rising bubbles in the center of the glass drag some liquid along with them. After this liquid reaches the top of the glass, it returns to the bottom along the sides of the glass. This downward flow can drag bubbles, especially small bubbles, downwards against the force of gravity.

In a similar manner, small rain drops can be pull up by air currents against the force of gravity.

So that’s why, when a cloud starts to form, it can continue to rise.

Water vapor is lighter than air. Hot humid air rises. As the humidity condenses to make a cloud, it continues to lift the cloud (inertia in part, heat of vaporization being released in condensation for another)

Eventually the droplets get big enough to fall fast enough to beat the uplift ‘from other causes’ and we get rain. Sometimes heavy rain. Falling from that rising developing thunderhead.

IMHO, this, too, argues that the best way to detect any increase or decrease of ‘warming’ would be just to look at the height of the tropopause. If more heat is arriving, it ought to raise the tropopause. If less heat, lower. ALL the heat is dumped, it’s just a question of how fast and is the variation enough to see it in tropopause hight and / or storm frequency.

Basically, to see the heat leaving, look for “clouds falling up”… and measure them.

A corollary to this ought to be that places like Alaska, that have thunderstorms only during the peak of summer, ought to be decent recorders of heat flux variation. Number, frequency, and dates of onset and ending of thunderstorms all ought to ‘give a clue’ about relative heat flows over time. Height of tropopause and rate of change seasonally ought to be useful too.

Now I wonder if we have any of that data for the last 100 years…

And a second corollary is that if Alaska only has thunderstorms in a few summer months, that indicates the heat flux level, or threshold, that CAUSES thunderstorms to dump the excess heat. The “lower bound” for convective cell acceleration to dump the added heat. (At the other extreme, in somewhere like the Mojave Desert that has sporadic thunderstorms, the tendency to END in the hottest parts of summer would indicate when heat makes water so scarce as to end the cycle. When the Spherical Heat Pipe Earth is so hot that the working fluid does not fall as rain and recycle, stopping the heat pump. (This is more speculative as deserts are largely the result of rain being stopped at earlier mountains, not a thermal limit per-se, so you would need to allow for that and adjust, if possible, to see the result. Perhaps a humidity / temperature nomogram).

The inevitable conclusion of those two speculations would be that were “Global Warming” real, it would have has it’s net result a northward migration of thunderstorm size and frequency… and not much else. The heat would still leave daily; it would just do so in slightly different locations. (And the ocean over the equatorial zone would evaporate more water to drive the tropical belt of thunderstorms even faster).

IMHO, you also need to allow for longer term dis-equilibrium states where heat IS stored in the ocean, only to be dumped later as lots of excess rain. That whole PDO / AMO cycle thing. So the Sun goes more active, we get more UV, it ends up as stratospheric heat and so, slower air cycling. The added sun slowly warms the ocean. Time passes, the sun takes a nap, and we get a colder ‘cold pole’ to the ‘heat pipe earth’ as the UV drops off; with a hotter ocean left over (as heating excess just ended). The net result OUGHT to be massive rains, as the ocean dumps heat via water cycling to the tropopause in excess storm formation.

And that is what we’ve seen the last couple of years. Added rains during a turn to ‘cold phase’ actions…

In Conclusion

If it really is “all about the convection”, then looking for size, frequency, and location of convective cells and records of precipitation ought to tell us when there were periods of greater and lesser heat flow into the system. When the sun was quiet and when it was active. That, in turn, ought to tell us if anything ‘unexpected’ is happening.

IMHO, the unexpected IS happening. The sun went quiet and we’ve got rain. Lots of it. Just as we’d predict from the preceding solar heated ocean and excess warming from the prior higher solar activity. That precipitation tells us the first derivative of heat change… A very useful thing… and right how it is saying “cold stratosphere, warm ocean, lots of rain establishing new equilibrium state”.

The preceding times of reduced rain also assert that when the sun was more active, IT was causing the warmer weather.

I think you can learn a lot from watching clouds falling up ;-)

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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14 Responses to Clouds Falling Up

  1. Seems a very good logical analysis. Cause and effect, scientific principles intact. Who would argue with that? Salutations EM!

  2. R. de Haan says:

    Have a look at this lecture Meteorology for Glider Pilots with more detailed process descriptions:

    http://the-white-knight-speaks.blogspot.com/2010/12/mteorologu-for-glider-pilots-gq-lecture.html

  3. Ralph B says:

    Alaskan thunderstorms…hmm..well from my understanding GW is supposed to affect northern areas more than tropical areas, so that should be a good falsifiable hypothesis. GCM’s have all missed the mark yet rather than admit defeat of the theory modelers look for reasons outside the program, “GW has paused and will come back with a vengeance”.
    I try to shave with Occam’s razor…this thunderstorm idea is a good strop in my opinion

  4. View from the Solent says:

    “If you are the type that carefully observes your beer, you will have noticed that sometimes the bubbles move down. ”
    Clearly visible in a glass of Guiness, just after pouring. I often wondered about that. But I will continue to buy and observe, in the interests of scientific research. It only takes 1 glass where it doesn’t happen to falsify the theory.

  5. Pascvaks says:

    Footnotes in History –

    “The most catastrophic California flooding of record occurred in the winter of 1861–1862, when there were record floods over the entire length of the state. During December and January, many places received 200% to 400% of their average rainfall. As a result, the Central Valley became a large (5,000 square mile) inland lake. The size of this lake made it twice as large as the Great Salt Lake and would currently make it the 18th largest lake in the world. The city of Sacramento was under several feet of water, and newly elected Governor Leland Stanford had to be rowed to his inauguration. Weather scientists estimate that the event was a once-in-a-30,000-year event.”

    “On January 1, 1916, rainmaker Charles Hatfield offered to bring rain to a parched San Diego, California for $10,000. He began to burn strange chemicals to summon rain, and it did begin to rain on January 10th. The problem was that it didn’t stop raining for days and damaging floods resulted. The city refused to pay him the money.”

    http://www.coolweather.net/staterainfall/california.htm

    Precipitation definitely says more than temperature! It also says a lot about temperature. I’d rather be hot and kinda dry than hot and real humid anyday, something to do with evaporation. Anyone who finds a good, recent paper on this area (Worldwide humidity vs temperature -or whatever) please post the link.

  6. Pascvaks says:

    FYI – “Interesting correlation: Sunspots vs Specific Humidity”

    http://tallbloke.wordpress.com/2010/08/08/interesting-correlation-sunspots-vs-specific-humidity/

  7. Pascvaks says:

    FYI (last;-) – “New paper – ‘Absence of Correlation Between Temperature Changes … and CO2′”

    http://wattsupwiththat.com/2011/01/01/new-peer-reviewed-paper-absence-of-correlation-between-temperature-changes-and-co2/

  8. Richard Ilfeld says:

    You are visiting, at the moment, near a gliderport where competitions are held each year — because of the fine convection. There is also a most interesting phenomona in the fall, when the sea breezes from each coast meet in the center of the state and create, with the convection, a fountain, that one can fly north & south on for a considerable time, rising with the raindrops, as it were.

  9. Hugo M says:

    E.M. Smith, you said

    So the Sun goes more active, we get more UV, it ends up as stratospheric heat and so, slower air cycling.

    As far as I know, the power maxima of UV irradiation occur during solar minima.

  10. Pascvaks says:

    At The Hockey Schtick – “Global Precipitation Fails to Obey Theory of Global Warming” Tuesday, July 19, 2011

    http://hockeyschtick.blogspot.com/2011/07/global-precipitation-fails-to-obey.html

  11. R. Shearer says:

    Ostwald Ripening, I believe, explains why droplets coalesce in the first place if one wishes to consider this to add to the picture.

  12. Interesting comment about those fine bubbles in a pint of Guinness. Here is a link that relates:

    http://diggingintheclay.wordpress.com/2011/07/18/curious-connections-in-climate-science-1/

  13. tallbloke says:

    Hi Chiefio and thanks for the visit and comment at my blog. Yes, the correlation I found between solar activity and specific humidity near the tropopause indicates that the sun makes clouds fall up. Higher humidity at higher altitude near the top of the solar cycle means the Sun is warming the atmosphere and enabling it to expand and hold more water at higher altitudes.

    But this also increases the area of the surfaces radiating heat to space, which is (maybe) why we often get La Nina conditions at the surface near the peak of the solar cycle, as more energy leaves the earth from the top of the atmosphere. At the same time, strengthening of the trade winds due to SOI pressure imbalance (cloud cover?) along the Humbolt current piles water westwards, pushing down and bringing cold ocean bottom water up against the South American coast.

    Cleverer people than me think hard about these internal dynamics. I do the easy stuff, the solar system dynamics providing the external drivers which cause these internal oscillations.

  14. E.M.Smith says:

    @Hugo M

    The recent solar funk has been accompanied by a drop of UV with a rise of shorter wavelengths and a resultant shortening of the height of the atmosphere. There is some variation with the exact band of UV you look at, so a few of them don’t show it as well as most, but there is a very significant drop of UV right now. Hey, I’m out in Florida summer sun with no sunscreen and I’m not bright red… (Normally I’m good for 20 minutes between 10 am and 2 pm and then it’s “red and blisters soon” land… that redhead gene and all…) At any rate, deep in some comment thread on WUWT there is an exchange between Dr. Svalgaard and me with respect to SORCE. Here is one article from there:

    http://wattsupwiththat.com/2010/12/22/sorces-solar-spectral-surprise-uv-declined-tsi-constant/

    Down in the comments you can find the exchange.

    @Gallopingcamel:

    Many thanks for that link…

    @Tallbloke:

    I like visits to your site. I just don’t comment much (mostly due to being a bit busy at the moment…) I’ve often found us looking at similar things from different angles and seeing the same results. Comforting…

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