User:Sj/Mountain storms

Cumulonimbus rising above the Black Mountains (North Carolina).

Mountain thunderstorms pose significant risks because of their consequences, especially for mountaineers, hikers and paragliders. Despite monitoring weather conditions to prevent accidents, disasters occurring during such phenomena often remain unpredictable and are the subject of novels or other stories.

Formation change

 
Formation of a cold front when the air in an uplift is stable or can not reach the top of the obstacle. The air is forced over the front and causes the formation of a low level jet stream .

Thunderstorms are formed when air in a layer of the atmosphere is unstable [1] . A parcel of air raised at the base of this layer is then warmer than the environment and rises. In rising, its temperature decreases by adiabatic expansion, and when the relative humidity of water vapor reaches saturation, this forms a convective cloud [1] . To form a storm, this layer must be very large and the temperature at the top of the cloud must be below −20C.

Mountains can help trigger atmospheric convection in three ways [2]  :

  • direct lifting at the level of free convection in unstable air, lifting with a synoptic wind that arrives w/ a component perpendicular to the slopes. The air is forced up the slope and into convection;
  • thermal forcing in an unstable situation where there is weak general circulation and diurnal warming. The mountain breezes then generate anabatic winds which also rise.
  • dynamic forcing when air is stable lower down, and circulation is blocked by the mountain, but the air is unstable at higher altitude. In this case general circulation is forced above this blocking layer and can reach the convective layer.

In a more general case, several effects may be present and if the synoptic wind is opposed to the anabatic wind, additional convergence occurs at the top of the mountain [3] . It is also possible to create a convergence zone behind the mountain when the synoptic wind can divide and go around it to meet again (ex. Puget Sound Convergence Zone ) that will promote convection [2] .

The uprising serves to not only destabilize the air and form convective clouds, but also to enhance its intensity [1] . As the rising air from the bottom of the slopes is hotter and humid than the surrounding air, the lifted index will be more negative, increasing the vertical extension of the cloud . A simple temperature difference of 2C is enough to greatly aggravate the violence of thunderstorms.

Special phenomena change

Mountain storms have particularities because of the proximity of clouds, the importance of electric fields, their rapidity of appearance, their particular danger. Sudden wind lift of a mass of air can radically change the initial conditions within them.

Immediate consequences change

Observable phenomena give an idea of the peculiarities of mountain storms .

Mountaineers are the most exposed to these phenomena[4], in ridges and pass passes.

In addition to the common phenomena related to the storm, larger electric fields cause unexpected warning signs related to the ionization of the air[5] . French mountaineers say they hear "bees": suddenly, on all surfaces, are small noisy discharges [6][7] . After this bee-sound, another observation is that the hair stands straight up over the head, and sparks can form between the teeth when one opens one's mouth. These are the results of electrical phenomena, already described in other situations, and known by the name of fire of St. Elmo or corona effect also called crown effect [8] .

Climbers, not very mobile, can find themselves trapped in a storm. The metal ice axes of climbing equipment can attract lightning, a great danger in these situations.

Indirect consequences change

 
Torrential flood in the canton of Uri, Switzerland .
 
Avalanche painting in the Alps, painted in 1803 by Philippe-Jacques de Loutherbourg .

The force of thunder, lightning, lightning, rain, hail, bursts and whirlwinds can cause other dangerous situations. Some natural phenomena are increased tenfold by altitude [9], in particular:

Prevention change

Weather forecasting is an essential tool for preventing accidents related to mountain storms [10] but does not prevent them altogether. Also many advice is provided in case of occurrence of a storm in the mountains [11] .

While television weather reports are not very useful for mountain practitioners, the sites of the various national meteorological services offer more accurate information.

For example, in the United States, the National Weather Service provides forecasts for every point in its territory, including the mountainous areas. The Meteorological Service of Canada and the UK Met Office also provide similar services.

In France, Météo France's departmental services also provide more specialized information [12] . In the same way, the consultation of the following sites is particularly recommended:

Stories of mountain storms in literature change

Novel change

Premier de cordée by Roger Frison-Roche touched on the spectacle of mountain climbing and the experience of high mountain guides in these extreme situations. It was adapted to the cinema in 1944: a film by Louis Daquin with Maurice Baquet; and again on television in 1999, in a TV movie directed by Pierre-Antoine Hiroz and Edouard Niermans.

Autobiographies change

 
Walter Bonatti in 1965
  • The Conquerors of the useless Lionel Terray: Surprised during the ascent of Mount Maudit, the author writes "At the beginning of the afternoon, as we approached the summit, the storm burst on us, sparks of sparks were formed above the pompons of our hats and I felt again the panic fear provoked in me by these outbursts of nature. "
  • The famous British climber Chris Bonington [15] said: "I have often bivouacked to wait for the good weather, spent nights in the storm ... In a storm, there is nothing to do but sit, wait for it to pass... ".
  • Mountain for a naked man [16] by Pierre Mazeaud. This book reports the tragedy on Mont Blanc on July 11, 1961 (where seven mountaineers were surprised by a violent storm on the pillar of Frêney, near the summit of Mont Blanc. One hundred and ten hours later, a helicopter landed three survivors at Courmayeur; among them Walter Bonatti [17] and Pierre Mazeaud [18] . ) This last one wrote: "Sitting on my stirrups, I use my piton, when I hear a striking ring somewhat resembling the phone. My companions, forty meters below, prick up their ears. Soon, I feel pain in my fingers, sparks run on my hammer. The carabiners on my shoulder stick to my fingers (...) A pendulum swing puts me near Pierrot, when a flash of a surprising glow hits him in the face, exactly in the ear where his hearing aid blackens. He falls into my arms, haggard, disgusted, without reaction ... ". Pierre Kohlmann [19] will not be killed instantly but the shock seems to have made him lose his mind. During the several days that will last the calvary of the descent, he will not say a word ... It will eventually collapse a few meters from the hello, last victim of a terrible storm that killed four mountaineers [20] .

Notes and references change

  1. 1.0 1.1 1.2 "Cumulonimbus". Glossaire de la météorologie. Météo-France. 2009. Retrieved 22 octobre 2016. {{cite web}}: Check date values in: |accessdate= (help)
  2. 2.0 2.1 Julien Vetter (5 juillet 2004). Contribution d’un code de calcul météorologique méso-échelle à la climatologie des pluies en zone de relief (pdf). Thèse de J. Vetter. Cemagref. p. 17-21. Retrieved 22 octobre 2016. {{cite book}}: Check date values in: |accessdate= and |date= (help).
  3. [[#CITEREF|]]
  4. "Randonneurs tués dans une coulée de boue en Corse : "On les avait prévenus du risque"". L'Obs (in French). juin 2015. Retrieved 2016-10-19. {{cite journal}}: Check date values in: |date= (help).
  5. "Les orages — CultureSciences-Physique - Ressources scientifiques pour l'enseignement des sciences physiques". CultureSciences-Physique - Ressources scientifiques pour l'enseignement des sciences physiques. 12 juin 2003. Retrieved 2016-10-19. {{cite journal}}: Check date values in: |date= (help).
  6. texte, Club alpin français Section du Sud-Ouest Auteur du (1985-12-01). "Revue pyrénéenne / Section du Sud-Ouest du Club alpin français et Ski-club bordelais". Gallica. p. p. 4,5 et 6. Retrieved 2016-10-19. {{cite web}}: |page= has extra text (help).
  7. [[#CITEREF|]].
  8. "Effet couronne sur les réseaux électriques aériens | Techniques de l'Ingénieur". www.techniques-ingenieur.fr. Retrieved 2016-10-19..
  9. 9.0 9.1 9.2 9.3 Chardon, Michel (1989). "Essai d'approche de la spécificité des milieux de la montagne alpine". Revue de géographie alpine. 77: 15–28. doi:10.3406/rga.1989.2727. Retrieved 2016-10-19..
  10. "Petit manuel de météo de montagne". Le Guide Météo (in French). 2015-09-05. Retrieved 2016-10-19..
  11. Champetier, JL. "QUE FAIRE EN CAS D'ORAGE". www.clubalpin-tarbes.org. Retrieved 2016-10-19..
  12. [[#CITEREF|]]
  13. "Conditions montagne générales, alpinisme, cascades, ski". www.fondazionemontagnasicura.org. Retrieved 2016-11-01.
  14. "KERAUNOS - Observatoire Français des Tornades et des Orages Violents - Prévision, suivi et étude des orages en France". www.keraunos.org. Retrieved 2016-11-01.
  15. Bonington, Chris (2013-07-15). Les horizons lointains: Souvenirs d'une vie d'alpiniste (in French). Primento. ISBN 9782511006566. Retrieved 2016-10-22..
  16. 1971 Arthaud, ISBN 208131343X, ISBN 9782081313439, 304 pages.
  17. Walter Bonatti (1997). Montagnes d'une vie. Paris: Arthaud. p. chapitre XII « La grande tragédie du pilier central (1961). ISBN 2-7003-1144-2..
  18. "Il y a 50 ans, la tragédie du Frêney". Le Dauphiné libéré. 17/07/2011. Retrieved 2016-10-21. {{cite journal}}: Check date values in: |date= (help).
  19. "[Association Pierre Kohlmann] Pierre Kohlmann". archive.is. Retrieved 2016-10-21..
  20. lyrik13travel (2012-09-10). "Walter Bonatti au pilier du Frêney (Mont Blanc)". Retrieved 2016-10-18.{{cite web}}: CS1 maint: numeric names: authors list (link).

Bibliography change

  • Thillet, Jean-Jacques; Schueller, Dominique (2009). Petit manuel de météo montagne. Topo guides. Glénat. p. 192. ISBN 978-2723463195. Thillet.
  • William R Cotton; George H Bryan; Susan C Van den Heever (2011). Storm and Cloud Dynamics (Second Edition). International geophysics series. Vol. 99. Academic Press. p. 807. ISBN 978-0-12-0885428. Cotton-2.{{cite book}}: CS1 maint: multiple names: authors list (link)
  • Dominique Musto (2014). Parapente Vol de distance. Éditions du Chemin des Crêtes. p. 208. ISBN 9-782953-919141. Musto.
  • Walter Bonatti, Mountains of a life, Arthaud, Paris, 1997, 401 p. ISBN 2-7003-1144-2 ( ISBN   <span class="nowrap">2-7003-1144-2</span> )
  • Lionel Terray, The Conquerors of the Useless, Paulsen Edition, coll. Guerin, 458 p., Illustrated and enriched with 450 photos and drawings for the most part unpublished ISBN 2911755197

Related articles change

Category:Thunderstorms Category:Pages with unreviewed translations