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Draught dynamics - any good web sites?



Sorry to be geeky and scientific... but are there any good web sites / pdfs about draught dynamics? I?m now in Eastern Thailand and have just found an unknown (to westerners anyway) grilled shaft with a strong steady cold draught coming out. As the outside air temp is in the 80s in daytime and 70 at night, is it possible to guess the travel distance of the draught through rock from its temp?

The karst landscape round here is very ancient - when you find new passageway, it tends to be large.

I don?t know if it?s a barometric draft (cave without another entrance to open air) or a theoretical through-trip to somewhere else.

Draught gurus and anoraks please help  :sneaky:

Highly unlikely, but are there any other cavers here in Prachinburi / Sa Kaeo (East Thailand) ? I have a number of very promising locations to have a sniff around...



Well-known member
I don't think I fit either of your descriptions above - but - if the draught is continuously outwards it's probably not a barometric draught. (If you've only been there once it's worth going there on several further occasions to see if the direction of the air current fluctuates - if it does, even if the outside temperature is always higher than the cave air temperature, it could well be a barometric draught.)

Assuming the draught temperature is lower than external air temperature then there is probably a higher entrance to any cave system beyond your shaft (as opposed to a lower entrance). I don't think you can use the strength of the draught to estimate the cave potential with any accuracy because there are so many variables affecting it which you can't determine without exploring the cave first.

That doesn't really help much does it?



New member
I've seen a number of papers that address the issue of air movement in caves, some of which are well complicated - as Pitlamp states.  For an overview of the basics you could try and find:

Wigley, T.M.L.,  Brown, M.C. (1976) ?The physics of caves? In Ford,T.D., Cullingford, C.H.D. (eds) The Science of Speleology, New York:Academic Press.

or drop me a PM and I'll see what else I have to hand.