Why do clouds form a 'tablecloth' which exactly fits the top of Table Mountain near Capetown, South Africa? Something about the table top tailors the clouds to fit it exactly. The thickness is smooth and even, at a rough guess about ten metres thick.

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    $\begingroup$ I assume something like this is meant: duckduckgo.com/… Weather does it here (La Palma island) in a similar way, up to really nice foehn walls :-) $\endgroup$
    – user18411
    Dec 16 '19 at 15:25

This is adiabatic compression of descending air. The air warms and clouds dissolve. The air is blown by a wind that's roughly perpendicular to the ridge, causing it to rise, cool and eventually condense on the windward side and sink and warm on the leeward.

  • $\begingroup$ What puzzles me is why the tablecloth is of such even thickness and fits the table top exactly. You couldn't have it without a table-shaped mountain, and there are not many of those. $\endgroup$ Dec 16 '19 at 17:56
  • $\begingroup$ It is not the mountain that defines the thickness but the dewpoint of the airmass, and that usually doesn't change over these small areas. The mountain is only the "excuse" for the airmass to rise and fall. The effect exist all over the world where air with some moisture is forced against a ridge. The extreme case is called foehn (Video mine: vimeo.com/190861312). $\endgroup$
    – user18411
    Dec 16 '19 at 18:56
  • $\begingroup$ Yes, the cloud looks very similar to the tablecloth on Table Mountain, but it doesn't seem to be table-shaped, probably because the mountain underneath it isn't table-shaped. $\endgroup$ Dec 16 '19 at 19:16
  • $\begingroup$ That's because you only see the front. It's a perfect "table" when seen from above, also because they are frequently limited by an inversion. Compare ak8.picdn.net/shutterstock/videos/4200238/thumb/1.jpg (La Palma, Cumbre Nueva, not my foto) and i.ytimg.com/vi/xDxNFRxqC1g/maxresdefault.jpg (Twelve Apostles, Capetown, not my foto). $\endgroup$
    – user18411
    Dec 16 '19 at 19:23
  • $\begingroup$ Yes, it's obviously the same phenomenon as the tablecloth on Table Mountain. $\endgroup$ Dec 17 '19 at 12:31

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