Exploding tree explained

A tree may explode when stresses in its trunk increase due to extreme cold, heat, or lightning, causing it to split suddenly.

Causes

Cold

Cold weather will cause some trees to shatter by freezing the sap, because it contains water, which expands as it freezes, creating a sound like a gunshot.[1] [2] The sound is produced as the tree bark splits, with the wood contracting as the sap expands. John Claudius Loudon described this effect of cold on trees in his Encyclopaedia of Gardening, in the entry for frosts, as follows:

Henry Ward Beecher records anecdotal evidence of the wood from which instrument cases and carrying boxes were splitting in temperatures of -70F in Captain Bach's travels near the Great Slave Lake. Linda Runyon, author of books on wilderness living, recounts her experience of the effect of cold on maple trees as follows:

Wally and Shirley Loudon reported the effect of the freeze of December 1968 upon their orchard in Carlton, Washington as follows:

To the Sioux of The Dakotas and the Cree, the first new moon of the new year is known, in various dialects, as the "Moon of the Cold-Exploding Trees".[3] [4] [5] [6]

Tree sap is a supercooled liquid in cold temperatures.[7] John Hunter observed, in his Treatise on the Blood, that tree sap within a tree freezes some 17 degrees Fahrenheit below its nominal freezing point.[8] [9]

Lightning

Trees can explode when struck by lightning.[10] [11] [12] The strong electric current is carried mostly by the water-conducting sapwood below the bark, heating it up and boiling the water. The pressure of the steam can make the trunk burst. This happens especially with trees whose trunks are already dying or rotting.[13] [14] The more usual result of lightning striking a tree, however, is a lightning scar, running down the bark, or simply root damage, whose only visible sign above ground is branches that were fed by the root dying back.[15]

Fire

Exploding trees also occur during forest fires[16] and are a risk to smokejumpers.[17] [18] [19]

Eucalyptus trees are known to explode during bush fires due to vaporised eucalyptus oils producing an explosive mixture with air.[20] [21] [22] [23] [24]

Explosive behaviour of Eucalyptus trunks has been observed in both laboratory tests and in wildfires in Australia.[25]

Aspen trees have also been observed to explode in wildfires.[26]

Steam pressure build up in tree trunks is theoretically unlikely to lead to an explosion in a rapidly moving fire front, although trees exploding after the initial front has passed or exploding through other mechanisms is entirely possible.[27]

April Fools’ Day hoax

Exploding trees were the subject of a 2005 April Fools' Day hoax in the United States, covered by National Public Radio, stating that maple trees in New England had been exploding due to a failure to collect their sap, causing pressure to build from the inside.[28] The root pressure in a maple tree is approximately 0.1MPa, one standard atmosphere, which is insufficient to cause a tree to explode.[29] [30]

See also

Footnotes

External links

Notes and References

  1. Book: Life at a High Altitude. Life in extreme environments. Judith Levin. The Rosen Publishing Group. 2004. 0-8239-3987-1. 10.
  2. May 2000. 28. 186, number 4. 0277-867X. Active Interest Media, Inc.. Backpacker Magazine. 72. Pop Goes the Forest. Jonathan Dorn.
  3. Book: Strange empire: a narrative of the Northwest. Borealis Books. Joseph Kinsey Howard. Minnesota Historical Society Press. 1994. 0-87351-298-7. 43.
  4. Book: The rise of Theodore Roosevelt. limited. Modern Library Paperbacks Series. Edmund Morris. Modern Library. 2001. 0-375-75678-7. 365.
  5. Book: The grasslands of the United States: an environmental history. limited. Nature and human societies. James Earl Sherow. ABC-CLIO. 2007. 978-1-85109-720-3. 105.
  6. Book: The revenge of Thomas Eakins. Henry McBride series in modernism and modernity. Sidney Kirkpatrick. Yale University Press. 2006. 0-300-10855-9. 337.
  7. Book: The physics of hockey. Alain Haché. JHU Press. 2002. 0-8018-7071-2. 8.
  8. Book: Familiar science, or, the scientific explanation of the principles of natural and physical science: and their practical and familiar applications to the employments and necessities of common life. David Ames Wells. Childs & Peterson. Philadelphia. 1856. 129–130. David Ames Wells.
  9. Book: The Works of John Hunter: with notes. John Hunter. James F. Palmer. Longman, Rees, Orme, Brown, Green, and Longman. London. 1835. III. 107. John Hunter (surgeon).
  10. Web site: Sequoiadendron giganteum — A 120 years old tree exploded by lightning. 2001-02-22. Arboretum de Villardebelle.
  11. Web site: Funnel cloud observed and lightning explodes a tree in the Lismore area. 2006-02-12. Michael Bath. Storm News and Chasing. Michael Bath and Jimmy Deguara.
  12. Nature Bulletin No. 458-A. 1972-05-20. Forest Preserve District of Cook County. George W. Dunne. Roland F. Eisenbeis. 2009-09-27. 2009-08-25. https://web.archive.org/web/20090825104831/http://www.newton.dep.anl.gov/natbltn/400-499/nb458.htm. dead.
  13. Web site: Tree, nature's lightning rod. West Virginia Lightning. 2009-09-27. https://web.archive.org/web/20080514172646/http://wvlightning.com/trees.shtml. 2008-05-14. dead.
  14. Popular Science. August 1959. 175. 2. 0161-7370. Bonnier Corporation. The Awesome Miracle of Lightning. Ira Wolfert. 186.
  15. Book: The organic gardener's handbook of natural insect and disease control. limited. Barbara W. Ellis . Fern Marshall Bradley . Helen Atthowe . Rodale. 1996. 9780875967530. 392.
  16. Book: Rain Forests of the World. Rolf. E. Johnson. Marshell Cavendish . New York. 238. 2009-09-25. 978-0-7614-7254-4. January 2002.
  17. 1968. The National Geographic Magazine. 134.
  18. Weick. Karl E.. 1993. The collapse of sensemaking in organizations: the Mann Gulch disaster. Administrative Science Quarterly. 10.2307/2393339. 38. 4 . 628–652. 2393339 .
  19. Book: Fire Fighters: Stories of Survival from the Front Lines of Firefighting . Clint Willis. Da Capo Press. 2002.
  20. The Eucalyptus of California - Section Three: Problems, Cares, Economics, and Species. Robert L. Santos. Alley-Cass Publications. Denair, California. 1997. dead. https://web.archive.org/web/20100602175115/http://library.csustan.edu/bsantos/section3.htm. 2010-06-02.
  21. Eucalytus Roulette (con't) Excerpted from America's Largest Weed. Ted Williams. Audubon Magazine. January–February 2002. Robert Sward. 2009-09-27. https://web.archive.org/web/20090909053902/http://www.robertsward.com/eucmore.htm. 2009-09-09. dead.
  22. Dold, J.W., Weber, R.O., Gill, M. et al. 2005. Unusual phenomena in an extreme bushfire in: Proceedings of the 5th Asia Pacific Conference on Combustion Adelaide. 2005
  23. McLaren, A. C. 1959. Propagation of flames in Eucalyptus oil vapour-air mixtures. Australian Journal of Applied Science 10: 321-328
  24. Williams, C. 2007. Ignition impossible: When wildfires set the air alight. New Scientist 2615
  25. Arne Inghelbrecht (2014) "Evaluation of the burning behaviour of wood products in the context of structural fire design" Master thesis submitted in the Erasmus Mundus Study Programme, International Master of Science in Fire Safety Engineering. The University of Queensland, Ghent University
  26. David Staples (2016) "Alberta battles The Beast, a fire that creates its own weather and causes green trees to explode" Edmonton Journal May 07, 2016
  27. Web site: Once and for all – trees do not explode. September 15, 2020. Wildfire Today.
  28. News: April Fool's: New England Suffers Maple Woes. Robert Siegel. NPR.org. 2005-04-01. National Public Radio.
  29. Web site: Buying genetic pets; Exploding sap trees; Non-blinking cows. April. Holladay. 2007-02-07. WonderQuest.
  30. Web site: Transpiration. David T.. Webb. BOT 311 Spring 2006 Syllabus. University of Hawaii at Manoa. 2009-09-27. https://web.archive.org/web/20090920144611/http://www.botany.hawaii.edu/faculty/webb/BOT311/BOT311-00/PlantWatMove/Transpiration.htm. 2009-09-20. dead.
  31. Frost. Mathematical and Philosophical Dictionary. 1795. Charles Hutton. 520. London. J. Johnson. Archived copy. Charles Hutton. 2009-09-27. 2011-06-05. https://web.archive.org/web/20110605101048/http://archimedes.mpiwg-berlin.mpg.de/cgi-bin/toc/toc.cgi?page=548;dir=hutto_dicti_078_en_1795;step=textonly. dead.

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