Breathing Caves©

 

 

Last weekend it was hot outside, the temperature was in the lower 80^o’s F (around 27^o C), I was hiking when suddenly, I felt a cold breeze, which must have been about 50^o F (10^o C)!  I followed the breeze and saw a cave, a “breathing cave”. 

 

A breathing cave, what’s that?

 

Breathing caves are also known as “blowing caves”, or “whistling wells”, and are caves that inhale and exhale on a regular seasonal and daily pattern.

 

This cave, if it is the same as the one mentioned in the history of Armstrong County, Pennsylvania, by J.H. Beers & Co, would likely have two openings, since constant water erosion would explain the sandy floor that was discovered inside.

 

In any case, the cave layout, whether it has an upper and lower entrance separated by a difference in elevation, and the temperature contrast between the internal cave air and the outside air, is what creates the cave respiration.

 

In the winter, the cave’s air temperature is usually warmer than the outside air temperature, this causes the warmer, less dense to rise and flow out along the roof of the cave’s entrance creating a warm breeze.  In the summer this pattern reverses, with the cave’s internal air temperature being lower than the outside air temperature causing the cooler, more dense cave air to sink and flow out along the floor of the cave’s entrance crating a cool breeze.  This pattern of cave breathing also happens daily as the outside air temperatures rises and falls above and below 50^o F (10^o C), since according to the U.S. National Park Service caves in the United States, remain a constant 52^o to 55^o F (11^o to 13^o C) year around.  Daily two-way cave airflow is most common during the spring and fall, since outside air temperatures during those seasons most often rise and fall above and below the cave’s constant internal temperature.

 

Today, the “chimney effect” and the physics of cave airflow is just a curious and interesting mental tidbit, but in the past, this was a vital bit of survival information for our cave dwelling ancestors and for pre-steam engine miners, who used this effect and fires both for warmth and to draw cool fresh air into the underground.

 

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That is all for now, and as always, until next time, Happy Trails!

 

 

Sources

 

J.H. Beers & Co; Armstrong County, Pennsylvania, Vol. 1, [J.H. Beers & Co, Chicago, 1914], https://archive.org/details/armstrongcountyp01jhbe/page/40/mode/2up, accessed September 6, 2024

 

Kedar, Yafit and Barkai, Ran; “The Significance of Air Circulation and Hearth Location at Paleolithic Cave Sites”, Open Quaternary, Vol. 5, No. 4, pages 1 to12, https://openquaternary.com/articles/52/files/submission/proof/52-1-985-1-10-20190612.pdf, accessed September 7, 2024

 

McGee, W. J.; “Ice Caves and Frozen Wells”, The National Geographic Magazine, December 1901, Volume 12, page 434 to 435, https://books.google.com/books?id=-z4PAAAAIAAJ&pg=PA432&dq=%22it+is+very+desirable+that+this+boundary+be+resurveyed%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwj2n8fdkqqIAxUrGVkFHeIaGYUQ6AF6BAgHEAI#v=onepage&q=%22it%20is%20very%20desirable%20that%20this%20boundary%20be%20resurveyed%22&f=false, accessed September 6, 2024

 

National Speleological Society; Journal Of Cave And Karst Studies, March 2021, Volume 83, Number 1, pages 8-9, https://caves.org/wp-content/uploads/Publications/JCKS/v83/cave-83-01-fullr.pdf, accessed September 6, 2024

 

Unknown; A Description of Howe’s Cave, [Weed, Parsons and Company, Albany, 1865], pages 10 to 11, https://books.google.com/books?id=JOXu0KCTX4wC&pg=PA10&dq=blowing+caves+temperature&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiH_5Xe96uIAxUaF1kFHR5VJ38Q6AF6BAgPEAI#v=onepage&q=blowing%20caves%20temperature&f=false, accessed September 6, 2024