Busa di Manna is a sinkhole in San Martino di Castrozza plateau which, besides producing incredibly low temperatures, is also a good model for swallowing Spiritus Mundi.
You may have already read in this site that Alchemy is not a polarity game, but a game of attraction. Nevertheless it is not an attraction between contraries or complementaries, but based on densities. We are always before a less dense Mercurius/Secret Fire/Spiritus Mundi attracted by a denser one, as opposed to the atmospheric models, and that’s why it is so difficult and hardworking to extract it from raw matters. And that’s also what an alchemical magnet is for.
But the Spiritus Mundi ( the name given to Mercurius when lingering in the atmosphere) has also another peculiarity, I retake here a previous post on Clovis Hesteau de Nuisement (2): “…..during the day, from the earth frame of reference, Secret Fire/Spiritus Mundi is not allowed to arrive to the ground, but limits itself to linger in the higher atmosphere layers. It is only during the night, when the Sun is on the other side of our planet, that Secret Fire can finally descend to the ground to go deeper and deeper. In fact Secret Fire seems to love dark conditions. A sunny day mostly implies cooking or magnetization, that’s to say destruction of the raw matter by exposition to hot and a successive cold…“. The paradox is that the Sun and Stars are huge producers of Secret Fire/Mercurius. So how does it come that Spiritus Mundi eventually manage to land? But let’s look at our natural sinkhole before trying an answer.
The karst plateau of San Martino di Castrozza is a mountain desert of utterly beauty, of about 50 sq. km., crowned by Dolomite peaks which are borders to the Italian regions of Trentino and Veneto. Like a real crown, beyond the peaks the plateau precipitates into the woods below, which in the nearby of Monte Agner reaches a vertical drop of one kilometer. In a poetic way it can be defined as a huge stone castle emerging from the Paneveggio forest.
And from Paneveggio forest, the violin wood (1), as a matter of fact it comes almost all the humidity and winds going uphill the natural Dolomitic stone castle. I have known the place since my childhood, while writing I can recollect my mother forcing the family to neglect the cableway and instead to climb up the old track from San Martino village, which was quite an adventure for us children under ten. She tempted us saying ” today I’ll bring you the moon”. And, indeed, she could not be more right.
But what my mother didn’t know was that the plateau was not a compact sedimentary rocky bulk, but the subsurface was actually traveled by a karst system like a Gruyère cheese. The karst system has been detected but not yet explored, due to the lack of a visible entrance hole, but sinkholes. Just 20 km. south-east San Martino plateau there spread out the Piani Eterni, or eternal planes (because of their vastness ), a huge caves system which they only recently started to explore. An expedition in 2014 proved that the system plunge vertically to 1052 m. under the sea level and stretch horizontally for kilometers absorbing the falling waters. At present there is no evidence that San Martino karst system runs along the same lines, though.
The karst system and Busa di Manna are strictly connected, as the latter is an high mountain sinkhole. Elevated sinkholes are basically extreme cold-air pools which are basically funnel shaped karst basins that determine strong radiative cooling and to cause their peculiarity they must present a route for surface water to disappear underground,
otherwise they are simple basins ( in fact, as you can see in the image on side, there are other deeper basins in the plateau). Busa di Manna, 2540 m. from sea level, is closely monitored by scientists and meteorologists as the weather pattern is specifically typical of elevated sinkholes. Winter temperatures – but only in the bottom of the sinkholes – can reach -50° C (winter 2015), a feature shared with the Carinthian Hohentauern sinkholes, but San Martino di Castrozza is much closer to Mediterranean. These sinkholes are known, among italian meteorologists, as “fabbriche del freddo” or icy factories.
On winter 2015 in Busa di Manna it has been measured a crazy difference of 20 degrees in just 12 vertical open meters: they are miracles of sinkholes. The frozen air only stagnates in sinkholes, a bit like the rain water that collects in puddles when it rains. If you exit the sinkhole at -40 ° C and move 100 meters maybe you’re not even at -20 ° C. Nevertheless the climate of the desert mountain gets deeply affected, because these extreme “ice factories”, though not in the open atmosphere, are however existent and not insulated. The weird is that the hotter the summer seasons in the forest below, the colder the “icy factories” sinkholes in winter. Among the other monitored sinkholes in San Martino plateau Busa di Manna is almost always the cold top winner.
The first researches on cold-pool formation in valleys and basins (for instance Geiger 1965) emphasized the role of long-wave radiation loss and the downward flux of sensible heat from the overlying atmosphere to counter this loss. This produced a cold-air layer over the slopes, which subsequently drained downslope into the nascent cold-air pool, causing it to grow and cool.
The reader can find a current state of the art research in exhaustive mathematical model Formation of Extreme Cold-Air Pools in Elevated Sinkholes: An Idealized Numerical Process Study by Günther Zängl, a research on elevated sinkholes phenomenon, considering almost the extreme situations in the Gstettneralm and Peter Sinks sinkholes. The model results indicate a number of necessary preconditions for the formation of an extreme cold-air pool in a sinkhole assuming the surface is to be covered with freshly fallen snow above a height of 1000 mI, while the case I’m examining in Busa di Manna presents bare rocks and melting snow. Below I provided an essential and brief summarizing of Zängl research:
“Apart from undisturbed clear weather, a small heat conductivity of the ground and an effective mechanism drying the low-level air during the cooling process are required. The importance of the heat conductivity results from the net cooling of the ground is only a small residual between the net radiative heat loss and the ground heat flux. Downward long-wave radiation is confirmed. The most notable difference between the model results and the observations concerns the vertical temperature profile in the sinkhole, which tends to be smoother in the model than in reality.
The larger ground–air temperature differences occur in the cloud-free regions where the net radiative heat loss of the ground is much larger. The drying is mainly achieved by ice cloud formation and subsequent sedimentation of the ice particles. The air in the center region of the sinkhole is now more than 15 K colder than outside, which in turn explains the virtual absence of katabatic winds in the inner part of the sinkhole. During undisturbed clear nights, the air in closed sinkholes cools very rapidly around sunset, followed by a more gradual cooling in the night proper. The cooling rate of the basin air is found to be close to the net radiative cooling rate around sunset but much smaller in the second half of the night, implying that a significant opposing heat source is present. Clements et al. (2003) also found that downslope flows along the side slopes of the basin are only of minor importance because they are hampered by the extreme static stability within the cold pool. Moreover, turbulent vertical fluxes of sensible heat were shown to be negligible except for a short period after sunset, indicating that the cooling of the basin air is maintained by radiative heat flux divergence. The absence of significant sensible heat fluxes also suggests that the net radiative heat loss of the surface is nearly balanced by heat conduction from the ground. The presence of a positive feedback effect of the cold pool on the downward long-wave radiation is confirmed, the ground heat flux is the leading term opposing the net radiation in all cases”.
Interesting the confirmation of a downward long-wave radiation. On the left a graphic taken from Zängl model, FIG. 10: “Downward longwave radiation” (contour interval 5 W m -²) at 0800 LT for simulations (a) Reference simulation, (b) 10-K-colder initial temperature profile, (c) Surface parameters for grassland instead of snow, and (d) Reisner1 cloud microphysics. The model for grass is on top right. But Zängl has not provided a model for melting snow-bare rocks, Busa di Manna’s summertime environment.