Tuesday, March 26, 2013

Should Eli Believe His Lying Eyes or Makarieva

James reminds Eli of  Makarieva et al in Atmospheric Chemistry and Physics as well as featuring on several blogs.  One can summarize the entire thing by noting that Makarieva claims that winds are formed when water vapor condenses decreasing the gaseous volume.  Were this the major process, air would move inwards towards the area where the condensation occurred.  Most others point out that the release of energy from the heat of condensation will blow the air outwards.  That's the summary

There was an almost infinite amount of mathturbation about this including the original paper, and Dr. Makarieva was very, well, insistent.

Eli OTOH is a member of the reality based community.  The Rabett likes to look at what is going on and figure out what it means before turning the math crank.  Recently Ms Rabett dragged Eli off into the mountains where he could actually watch the clouds form.  He could tell you what happened, but in this world we have the video.

There are lots more of these on You Tube and in all of them when the cloud forms it expands, the condensed water vapor provides an excellent tracer of the process,

So who should the bunnies trust.


Brian said...

Damn these lying eyes of mine.

Anonymous said...

The video appears to show cloud formation in something resembling a constant gradient, with the general wind direction moving from the right of the screen to the left, while the condensation front moves to the right, opposite the prevailing wind direction.

While the cloud appears to expand against the prevailing wind, the moving condensation front doesn't appear to be expanding due to outward expansion (i.e., it didn't "blow the air outwards") or a reversal of the prevailing wind. I'm not a meteorologist, but this doesn't appear to provide a convincing case against (or for) Makarieva, if the release of heat from condensation isn't enough to observe changes in wind patterns superimposed on the prevailing gradient.

OTOH, if there wasn't a strong prevailing gradient on top of which the cloud formation was observed, it might provide a better example to judge. I could very well be missing something here, as I'm sure someone will let me know. I'm not defending Makarieva, as I think strong claims require strong evidence; I'm just not sure this example works.

Taylor B

EliRabett said...

For a clear example look at 0.27 sec in the center of the screen underneath the large cloud mass as a smaller cloud forms detached from the larger one. In almost all cases the newly formed clouds grow and expand (there are a couple which do disappear). That is the point, not the winds. Makarieva, et al would tell you that when a cloud forms (condensation) it pulls the air mass inward.

Anastassia Makarieva said...

Some information relevant to you query can be found here. In brief, when we see a cloud increasing in size, this does not mean that the air is expanding. It is the area of convergence (shrinking) that is growing.

EliRabett said...

If you go into a region with strong updrafts you can actually see the water aerosol form and expand as it does. Water vapor is not mysteriously sucked into the cloud.