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Learning Weather • • • A resource study kit suitable for students grade seven and up, prepared by the Atmospheric Environment Service of Environment Canada Includes new revised poster·size cloud chart Decouvrons la meteO ... Pochettes destinees aux eleves du secondaire et du collegial, preparees par Ie service de I'environnement atmos heri ue d'Environnement Canada Incluant un tableau revise descriptif des nuages

Learning Weather Decouvrons la meteo A resource study kit, contains: Pochette documentaire comprenant:

1. Mapping Weather 1. Cartographie de la meteo A series of maps with exercises. Teaches how Serie de cartes accompagnees d'exercices. Oecrit weather moves. Includes climatic data for 50 Cana­ les fluctuations du temps et fournit des donnees dian locations. climatologiques pour 50 localites canadiennes. 2. Knowing Weather 2. Apprenons a connaitre la meteo Booklet discusses weather events, weather facts Brochure traitant d'evenements, de faits et de legen· and folklore, measurement of weather and several des meteorologiques. Techniques de I'observation et student projects to study weather. de la prevision de la met eo. Projets scolaires sur la 3. Knowing Clouds meteorologie. A cloud chart to help students identify various cloud 3. Apprenons a connaitre les nuages formations. Tableau descriptif des nuages aidant les elilves a identifier differentes formations.

Cat. No. EN56·5311983·E Each kit $4.95 Cat. N° EN56·5311983F Chaque pochette: 4,95 $

Order kits from: Commandez les pochettes au : CANADIAN GOVERNMENT PUBLISHING CENTRE CENTRE D'EDITION DU GOUVERNEMENT DU OTTAWA, CANADA CANADA, K1A OS9 OTTAWA (CANADA) K1A OS9

Order Form (please print) Bon de commande Veuillez m'ex pedier _ _ exemplaire(s) de la pochette Please send me _ _ copy(ies) of Learning Weather at $4.95 "Decouvrons la meteo" it 4.95 $ la co pie. N° de cat. per copy. TOTAL $ . Cat. No .: EN56-53/1983E . EN56·53/1983F_ Name Nom School Adre sse Add ress City Ville Province Postal Code Province Code postal Ci·joint $ N° de compte o Account No. 0 Enclosed $ o B~i::ter Card 111111111111111 Expi ry Dat e Bank Date d'exp iration Signature Banque Signature Orders prepaid by peslar money order or cheque must be made to Ihe order of the Receiver General for Canada and addressed to Ihe Canadian Govern­ Les commandes sont payables a I'avance par cheque ou mandai rail a menl Publishing Centre, Ottawa (Canada) K lA 059. Also available through I'ordre du Receveur general du Canada et doivent eire adressees au Centre authorized bookstore agents or your local bookseller. Add 20% to prices for d'edition du gouvernemenl du Canada. Otlawa (Canada) K1A OS9 En vente books to be shipped outSide Canada Payable in Canadian funds aussi chez les agents libraires agrees ou chez volre libraire Telephone (819) 997-2560 Telex 053-4296 Egalement disponible en fram;ais: "Decouvrons la meteo" Also avaifable in English: "Learning Weather" N" de cat.: EN56-5311983F. Cat No EN56-531t983E. Canada The two articles by Barry Grace in this issue c;I,k«t/< Summer / Ete 1987 Vol. 9 No.3 - the Alberta chinook and the related phenomenon of soil erosion - are, in a sense, FROM THE EDITOR's DESK 51 a reminder that the name of our publication CHINOOKS 52 is connected with that infamous weather By Barry Grace phenomenon. In this issue we are revisiting the chinook and some of its important CHINOOK BIBLIOGRAPHY 55 impacts. Chinook's first issue in the fall of HOT AND COOL JULY BREEZES 61 1978 provided a satellite view of the cloud Weather Map Series, July 8 to 14, 1987 arch accompanying this warm, dry and gusty By Hans VanLeeuwen wind. ANSWERS TO ICEBERG QUESTIONS (Chinook Vol. 9 No.1) 61 Since the magazine has been in existence now for almost ten years, we felt it proper to WIND EROSION OF SOILS ON THE CANADIAN PRAIRIES 62 provide the readers with an up-to-date and By Barry Grace rather extensive bibliography of articles and CLIMATE QUIZ 64 books published on this most Canadian of weather phenomena. WINTER OF 1986-87 IN REVIEW 65 In this issue we also want to welcome to our By Amir Shabbar readership a large number of weather ob­ servers. Through the kind generosity of the EDITORIAL BOARD / CONSEIL DE REDACTION Atmospheric Environment Service, Chinook will be distributed to a select number of these Howard Freeland John W. Loder most valuable contributors to meteorology in Institute of Ocean Sciences Bedford Institute of Oceanography Canada. Sidney, British Columbia Dartmouth, Nova Scotia Weather observers playa vital role in piec­ Barry Grace John Maybank ing together the complex weather and climate Agriculture Canada Research Branch Saskatchewan Research Council picture. They lilre a group who go back in Lethbridge, Alberta Sa skatoon, Sas katchewan history more than two centuries - well before Yves Gratton Jerry Salloum Canada's Weather Service existed- and who Universite du Quebec a Rimouski Don Mills Collegiate can be found in many communities across Rimouski, Quebec City of North York, Ontario the length and breadth of Canada. Hans VanLeeuwen (Chairman) We welcome your comments and look Richard Leduc Ministere de l'environnement Atmospheric Environment Service forward to your contributions. We will en­ Quebec, Quebec Downsview, Ontario deavour to publish your observations in Chinook, particularly if they pertain to EDITOR Hans Vanleeuwen REDACTEUR TECHNICAL EDITOR Edward J Truhlar REDACTION TECHNIQUE peculiar, unusual orjust interesting weather BUSINESS MANAGER J Carr McLeod GESTIONNAIRE phenomena. Some of these are best described ARTWORK Bill Kiely and Joan Badger ILLUSTRATION TRANSLATION Joanne Gagnon Pacini TRADUCTION with pictures. We thus intend to start, with FOUNDER AND EDITOR 1978-1984 Michael J. Newark FONDATEUR EDITEUR 1978-1984 your cooperation, an Observer's Corner for ISSN 0705-4572 the purpose of sharing your observations and Published by: Publie par: insights with the meteorological and oceano­ Canadian Meleorological and Oceanographic SOCiety La Societe canadienne de meteorologie et d'oceanographie graphic communities in Canada. This desk has thus far not been flooded Prinled and produced in Canada and published quarterly by Edite et imprime au Canada Chinook est publie lous les with letters or contributions from our read­ Ihe Canadian Meteorological and Oceanographic Society. trois mois par la Societe canadienne de meleorologie ers. So we will assume either they are in the Suite 903. 151 Slater Sireet. Otlawa. Onl. K1P 5H3 Annual et d·oceanographie. Suite 903. 151. rue Slater. Ollawa subscription rates are $10.00 for CMOS members. $12.00 (Ontario) K1P 5H3. Les frais d'abonnement annuel sont de mail or you are still working on them. The for non-members and $15.00 for institutions. Contents copy- 10.00$ pour les membres de la SCMO. de 12.00$ pour bottom line is that we need to hear from you, rlg~t ~ the authors 1987 Copying done for other than les non -membres et de 15.00 $ pour les inslitutions Les personal or Internal rcference use without the expressed auteurs detiennent Ie droit exclusif d'exploiter leur oeuvre the good news, the bad news and your permission oJ the CMOS IS prOhibited. All correspondence litteraire (© 1987) Toute reproduction. sauf pour usage per- contributions. including requesls for special permiSSion or bulk orders sonnel au consultation interne, est interdite sans la permis- should be addressed to Chinook at the above address_ sion explicite de la SCMO. Toute correspondance doit ~Ire We also continue to need your assistance envoyae au Chinook a I'adresse ci-dessus. y compris les in spreading the word and in getting the Second Class Mail Registration No. 4508 demandes de permission speciale et les commandes en magazine into secondary schools, flying and Summer 1987 Dale of issue - Seplember 1987 gros. yacht clubs, radio and TV stations and all ~ourrier de deuxieme classe - enregistrement nO 4508 those groups who in one way or another have Eta 1987 Date de parulion - septembre 1987 an interest in weather and the oceans. Hans VanLeeuwen COVER COUVERTURE Striking views of the Chinook Arch near sun- Prises remarquables de l'arche du chinook, Contributions, enquiries, comments and sug­ set, with melting snow shown in the lower peu avant Ie coucher du solei!, ainsi qu'une gestions from readers are welcome. They right photograph. Courtesy: Evan Gushul, image de la fonte des neiges, en bas, a should be addressed to: retired photographer, Agriculture Research droite. Gracieusete de : Evan Gushul, photo- Editor, Chinook, Suite 903, 151 Slater Street, Station, Lethbridge, Alberta. graphe a la retraite, Station de recherches, Ottawa, Ont. K1 P 5H3. Agriculture Canada, Lethbridge, Alberta.

51 CHINOOKS by Barry Grace

Chinook Arch at Lethbridge. Courtesy: Evan Gushul, retired Photographer, Agriculture Canada, Lethbridge.

The climate of southern Alberta was 10 often referred to in historical records. Early explorers and traders in the late 1700s noted the warm west winds and 0 mild winter climate of the area, where the climate is dominated by chinook winds. Few regions in Canada are so -10 profoundly influenced by the direct and ~ indirect effects of a specific weather S phenomenon. ~ -20 Q) Chinook is the name applied to c. E Q) strong, warm, dry winds that sweep f- -30 Id j down the eastern slopes of the Rocky 800 E Mountains. Early North American leg­ o ends claim that the winds originated in -g ~ -40 the homeland of the Chinook Indians, 400 ~ who dwelt in the Columbia River area of Washington State. In other countries >. such as Austria, New Zealand and o~ 28 30 2 8 10 Japan, the winds that develop along the December 1984 January 1985 lee sides of mountain ranges are re­ ferred to as foehn winds. Figure 1 Daily maximum, minimum and Figure 2 Surface analysis, 0600 GMT, for Chinook winds in North America mean temperatures and daily total wind run January 2, 1985 indicating a high pressure influence the climate of Alberta, Sas­ for late December 1984 and early January over the Rocky Mountains and a low pres­ katchewan, Montana and North Dako­ 1985. sure over southern Saskatchewan. Chinook ta. In most of these, an occasional conditions result from such weather patterns. warming is the only effect of a passing chinook. In southern Alberta, however, kmlh are common. Figure 1 displays over the mountains (Figure 2). Since the chinook winds are a dominating temperature and wind speed data for the mountains lie in the path of and at climatic factor. Here, the frequency is the chinook conditions oflate December right angles to the main westerly air greatest, with the Lethbridge vicinity 1984 and early January 1985. It can be stream, disturbances are set up in this receiving the most chinooks. seen that the maximum and minimum stream in the form of a wave train with The chinook is a meteorologically temperatures for January 1 differ by troughs and crests roughly parallel to complex phenomenon. Simply stated, more than 25°C. the mountain ranges (Figure 3). These the chinook is a warm, dry wind de­ A chinook is the result of the passage are very similar to those in a small scending the leeward side of the moun­ of a typical mid-latitude low-pressure water stream. After water flows over a tains. Daily temperature changes of centre into which air is drawn at the lee few small pebbles on the bed of the 20°C or more are possible during winter of the Rocky Mountains. Often this is stream, little waves appear in the water chinooks, and wind speeds of 60 to 100 associated with a ridge of high pressure just downstream from the pebbles.

52 Chinook Summer/Ete 1987 The size and amplitude ofthe chinook wave system depend mainly on the strength of the upper westerly winds and other factors, such as the air mass conditions and the local topography. This system is similar to our stream's, where the size of the waves depends on the speed of the stream flow and on the size and shape of the pebbles on the streambed. With very light winds the amplitude ROCKY of the chinook wave may not be suffi­ -MOUNTAINS cient for the trough to reach the ground. In this event the warm chinook air may Figure 3 Diagram of chinook waves that displace cool air over the Rocky Mountain foothills lie a thousand metres above the ground and the Prairies, with the Chinook Arch at the crest ofthe waves (adapted from Brinkmann surface. On each crest of the chinook and Ashwell, 1968). wave train, a cloud formation known as the Chinook Arch may form within a linear band of lenticular altocumulus cloud. The Chinook Arch forms parallel to the mountains and stretches for tens to hundreds of kilometres in a roughly north-south direction (see Figure 3). Chinooks are strongest in the foot­ hills, where some areas are more prone to chinooks than others. Chinooks eas­ ily channel through mountain passes. Places near the Yellowhead Pass, Kick­ ing Horse Pass, and Crowsnest Pass are prime chinook areas, with Crowsnest Pass in southern Alberta experiencing them the most frequently. West ...

53 Photograph of RCAF Station, Claresholm, Alberta, taken during the 1950s, showing typical wave clouds associated with a chinook situation.

'\ Ft.McM URRAY Ft.McMURRAY

• PEACE RIVER • PEACE RIVER

< 50

EDMONTON

MILES o 50 100 I I I I " o 50 100 150 KILOMET'RES Dramatic melting of snow due to an Alberta chinook, from December 30, 1983 through Figure 5 Number of days with maximum Figure 6 Number of hours each year with January 3 to January 5, 1984. Courtesy: temperatures of 4.5°C or higher in January wind speeds equal to or exceeding 50 kmlh John Kolpac, Agriculture Canada Photo­ and February (adapted from Bentley). (adapted from Bentley). grapher, Lethbridge.

54 Chinook Summer/Ete 1987 REFERENCES Station, Lethbridge, Alberta, 39 pp. Bentley, F. (No Date): This Land of Alberta. Alberta Agriculture, University of Calgary, 1980: Chinook. UMATIC Video Tape, A. 104 pp. Jeremko, Producer, Dep. of Communications Media, 25 min. Brinl~mann, W. and I.Y. Ashwell, 1968: The Structure and Movement of the Chinook in Alberta. Atmosphere, VoI. 6, Barry Grace is a Research Scientist specializing in Agricultural 241-250. Meteorology at the Agriculture Canada Research Station in Grace, B. and E.H. Hobbs, 1986: The climate of the Lethbridge Lethbridge, Alberta. Agricultural Area: 1902-1985. LRS Mimeo 3, Agric. Canada Res. Photograph credits: Lethbridge Research Station Archives.

RESUME Les vents forts, chauds et secs qui balaient les pentes de correlation entre l'eco ulement de l'air qui franchit les montagnes et l'est des Rocheuses portent Ie nom de Chinook. Ces vents influent sur une configuration type des ondes et des nuages. Le flux d'air les climats de l'Alberta, de la Saskatchewan, du Montana et du descendant du cote sous Ie vent de la montagne produit de l'air sec et Dakota du Nord. C' est dans le sud de I'Alberta que les chinooks sont plus chaud accompagne de vents forts . Les chinooks exercent de les plus frequents. Lars des chinooks d' hiver, il est possible d'observer fortes repercussions sur les temperatures et les taux d'humidite des variations de temperature de 20°C au plus et, souvent, des vents d'hiveret, en outre, ils causent souvent des reactions physiologiques et d'une vitesse de 50 d 100 km/h (figure 1). En regle generale, les psychologiques. Les chinooks peuvent avoir des consequences chinooks resultent de la circulation intense de l'air qui traverse la importantes sur la fonte des neiges et sur Ie contenu en eau du sol, y chaine montagneuse. Ce phenomene est illustre d la figure 2. En compris l'erosion. Les figures 4, 5 et 6 illustrent quelques effets du observant les images de nuages, on peut voir qu'il existe une chinook en Alberta.

CHINOOK BIBLIOGRAPHY 1886/1 Bowerman, A. The Chinook Winds and Other Climatic 1948/1 Hoover,O.H. Effect of Chinook (Foehn) Winds on Snow Conditions of the Northwest. Trans., Historical and Scientific Cover and Runoff. International Union of Geodesy and Society of Manitoba, No. 22. Geophysics, International Association of Hydrology, Transac­ 1888/1 McCaul, C.C. South Alberta, and the Climatic Effects of tions, VoI. 2, 86-100. the Chinook Wind. Am. Meteorol. J., VoI. 5, 145-159. 195111 Henson, W.R. Chinook Winds and Red Belt Injury to 1901/1 Fruh, J. Fohn in Fort Good Hope 66°20'N am Mackenzie Lodgepole Pine in the Rocky Mountain Parks Area of Canada. River (Kanada). Meteorol. Zeit., VoI. 13,36. Dep. of Agriculture, Div. of Forest Biology, Contrib. No. 28, pp. 1907/1 Buckingham, H. The "Southwest" or "Wet" Chinook. 62-64. Mon. Weather Rev., VoI. 35, 175-176. 196111 Glenn, C.L. The Chinook. Weatherwise, VoI.14, 175-182. 1907/2 Grassham, R.T. The "Dry" Chinook in British Colum­ 196112 McCabe, H.J. A New Look at Chinooks. Dep. of Com­ bia. Mon. Weather Rev., VoI. 35, 176. munications No. 15, Can. Dep. of Transport, MeteoroI. Br., 1910/1 Stupart, R.F. The Chinook in Southern Alberta and Calgary, Alta., 4 pp. Temperature Inversions at Sulphur Mountain, Banff. Proc. 1963/1 Thomas, T.M. Some Observations on the Chinook Roy. Soc. Can., Ser. 3, VoI. 4, No.3, 51-52. "Arch" in Western Alberta and North-Western Montana. 1936/1 Johnson, H.N. The Dry Chinook Wind. Bull. Am. Weather, VoI. 18, 166-170. Meteorol . Soc., VoI. 17,23-27. 1965/1 Marsh, J.S. The Chinook in Southern Alberta and Its 1938/1 Larson,O.T. Remarkable Chinook in Alberta. Bull. Am. Geographic Significance. M.A. Thesis, University of Alberta, Meteorol. Soc., VoI. 19,408-409. Calgary, Alta. 194111 Osmond, H.W. The Chinook Wind East of the Canadian 1967/1 Ashwell, I.Y. and J.S. Marsh Moisture Loss Under Rockies. Can. J. Res., A, VoI. 19,57-66. Chinook Conditions. Proc. of the First Canadian Conference on 55 Micrometeorology (1965), Part II. Can. Dep. of Transport, 197911 Hicks, R.B. and T. Mathews Impact of Chinooks on Meteorol. Br., Toronto, Ont., pp. 307-314. Calgary's Air Quality: Acoustic Sounder Observations of 1967/2 --and -- Studies of the Chinook at Calgary: A Atmospheric Stability. Water, Air, Soil, Pollut., Vol. 11, Progress Report. The Albertan Geographer, Vol. 4, 45-47. 159-172. 1967/3 Longley, R.W. The Frequency of Chinooks in Alberta. 1979/2 Mathai, C. V.; A.W. Harrison and T. Mathews Effect of The Albertan Geographer, Vol. 3, 20-21. Chinooks on the Atmospheric Aerosol size Spectra and Light 1967/4 -- The Frequency of Winter Chinooks in Alberta. Scattering Coefficient in Downtown Calgary During the Atmosphere, Vol. 5, No.4, 4-16. Winter of 1978-1979. Atmosphere-Ocean, Vol. 17 (Abstract, 1968/1 Brinkmann, W.A.R. The Definition of the Chinook in Congress issue), p. 23. the Calgary Area. M.Sc. Thesis, University of Calgary, Dep. of 1979/3 Mathews, T. and R.B. Hicks Typical Features of Geography, Calgary, Alta., 115 pp. Atmospheric Turbulence Profiles Associated With Chinooks. 1968/2 --and I.Y. Ashwell The Structure and Movement of Atmosphere-Ocean, Vol. 17, 125-134. the Chinook in Alberta. Atmosphere, Vol. 6, No.2, 1-10. 1979/4 Tromp, S.W. Studies on the Origin and Biological 1968/3 Walker, E.R.; O. Johnson and W.H. Boswell Meteor­ Effects of the Chinook in Western Canada. In: Biometeorologi­ ological Characteristics of Chinooks in Alberta. Suffield Tech. cal Survey, Vol. 1, 1973-1978, Part A: Human Biometeorology, Note No. 227, Defence Res. Establ., Ralston, Aita., 13 pp + 15 fig. S.W. Tromp and J .J . Bouma (Eds.), Heyden & Son Ltd., London, 1970/1 Brinkmann, W.A.R. The Chinook at Calgary (Canada). pp. 191-194. Arch. Meteorol. Geophys. Bioklimatol., Ser. B., Vol. 18, 1980/1 Buhrmann, H.G. and D. Young Canoeing Chinook 269-278. Country Rivers. Unileth Press, Lethbridge, Alta., 154 pp. 1970/2 Nkemdirim, L.C. Measurement of Chinook Efficiency 1980/2 Hage, KD. An "Edmonton Chinook". Chinook, Vol. 2, and Its Spatial Distribution. The University of Calgary, No.2, 28-29. Weather Research Station, Tech. Rep. No.2., 21 pp. 1980/3 Mathai, C.V.; A.W. Harrison and T. Mathews Aerosol 1971/1 Ashwell, I.Y. Warm Blast Across the Snow-Covered Particle Size Distribution (0.1- 1.0 fLm) During the Chinooks of Prairie. The Geographical Mag., Vol. 43 , 858-863. 1979 Over Calgary, Canada. J. Appl. Meteorol., Vol. 19, 1971/2 Brinkmann, W.A.R. What Is a Foehn? Weather, Vol. 26, 515-520. 230-239. 1980/4 Swanson, R.H. Surface Wind Structure in Forest Clear­ 1971/3 Holmes, R.M. and K.D. Hage Airborne Observations of ings During a Chinook. Proc., Western Snow Conr., 48th Ann. Three Chinook-Type Situations in Southern Alberta. J . Appl. Meeting, April 15-17, 1980, Laramie, Wyoming, pp. 26-30. Meteorol. , Vol. 10, 1138- 1153. 1981/1 Bryson, R.A. Chinook Climates and Plains People. 1971/4 Riehl, H. Unusual Chinook Case. Weather, Vol. 26, Great Plains Quart.,Vol. 1, 5-15. 241-246. 1981/2 Leelananda, S.A. A Doppler Acoustic Sounder for the 1971/5 Webb, B.L. Chinooks and Blizzards. The Beaver, Outfit Investigation of the Southern Alberta Chinook. Ph.D. Thesis, 301,31-33. University of Calgary, Dep. of Physics, Calgary, Alta. 1972/1 Kellie, A.R. Low-Level Atmospheric Structure Over 1981/3 -- and T. Mathews Method of Correcting Wind Calgary in Pre-Chinook Conditions. M.Sc. Thesis, University Profiles Obtained Using Doppler Acoustic Sounder, for Refrac­ of Alberta, Dep. of Geography, Edmonton, Alta. tion Effects. Proc., Int. Symp. on Acoustic Remote Sensing of 1972/2 Riehl, H. On the Climatology and Mechanisms of the Atmosphere and Oceans. June 22-25, 1981, University of Colorado Chinook Winds. Bonner Meteorologische Abhand­ Calgary, Calgary, Alta., pp. II-85- II-97. lungen, Bonn. No. 17,493-504. 1981/4 --; S.K. Aggarwal and T. Mathews Temperature 197311 Golding, D.L. Chinooks May Influence Forest Manage­ and Velocity Turbulence During the Onset of Chinooks. Ibid., ment. Canadian Forestry Service Northern Forest Research pp. VI-12-VI-26. Centre, Edmonton, Forestry Rep. 2(3), p. 3. 1982/1 Drews, M.D. An Aid to Forecasting Chinooks Over 1976/1 Catchpole, A.J.W. and D. Milton Sunnier Prairie Southern Alberta. Tech. Memo. TEC 880, Atmospheric Cities - A Benefit of Natural Gas? Weather, Vol. 31, 348- 354. Environment Service, Downsview, Ont., 20 pp. 1976/2 Lester, P.F. Evidence of Long Lee Waves in Southern 1983/1 Coxson, D.S. and KA. Kershaw Nitrogenase Activity Alberta. Atmosphere, Vol. 14,28-36. During Chinook Snowmelt Sequences by Nostoc Commune in 1976/3 Masterton, J.M.; R.B. Crowe and W.M. Baker The Stipa-Bouteloa Grassland. Can. J . Microbiol., Vol. 29,938-944. Tourism and Outdoor Recreation Climate of the Prairie 198411 Mathews, T.; P.F. Lester and R.B. Hicks Sodar Provinces. Publ. in Applied Meteorology, REC-1-75, Atmos­ Observations of Chinooks and Arctic Front Passages Across the pheric Environment Service, Downsview, Ont., 221 pp. Eastern Slopes of the Canadian Rockies. Atmosphere-Ocean, 197711 Danielewicz, Z.W. Some Characteristics of Large Scale Vol. 22, 328-342. Winter Chinooks in Southern Alberta. M.Sc. Thesis, Univer­ 1984/2 MTB Consultants Ltd. Chinook Country Tourism Des­ sity of Calgary, Dep. of Geography, Calgary, Alta. tination Area Study. Prepared for Alberta Dep. of Tourism and 1977/2 Golding, D.L. Snowpack Evaporation During Chinooks Small Business by MTB and ICL (Interplan Consultants Ltd.), Along the East Slopes of the Rocky Mountains. Proceedings, 181 pp. Second Conference on Hydrometeorology, October 25-27, 1984/3 Prozny, E.A. The Chinook Winds. Climatic Perspectives, 1977, Toronto, Ont., Am. Meteorol. Soc., pp. 251-254. Vol. 6, No. 6, pp. 6B-7B. 1977 /3 Leahey, D. A Preliminary Examination of Poor Air Quality 1985/1 Bohlender, D.A.; P.J. Irwin and T. Mathews Observa­ Levels in Calgary in Relation to Mountain Generated Wind tions of Sound Propagation During a Southern Alberta Systems. Atmosphere, Vol. 15 (Abstract, Congress issue), p. 37. Chinook. J. Acoust. Soc. Am., Vol. 77, 2043-2049. 1977/4 Lester, P.F. and J.I. MacPherson Waves and Turbu­ 1985/2 Mathews, T. and R.B. Hicks Natural Processes in the lence in the Vicinity of a Chinook Arch Cloud. Mon. Weather Lower Atmosphere: An Acoustic Sounding Technique Is Being Rev., Vol. 105, 1447-1457. Used to Study Alberta Chinooks and Turbulence Associated 197811 Golding, D.L. Calculated Snowpack Evaporation Dur­ With Them. Univ. of Calgary, Dep. of Physics, Calgary, Alta. ing Chinooks Along the Eastern Slopes of the Rocky Mountains 198611 Christison, T. Snow-Eater. Chinook Winds Turn Win­ in Alberta. J. Appl. Meteorol., Vol. 17, 1647-1651. ter Into Spring in an Hour. Nature Canada, Vol. 15, No.2, 1978/2 Newark, M. A Satellite View of the Chinook. Chinook, 16-22. Vol. 1, 4-5. 1986/2 Hage, K.D. Survey of Destructive Winds in Alberta and 1978/3 Nkemdirim, L.C. and K. Leggat The Effect of Chinook Saskatchewan: Climatological Analysis of Tornadoes, Thun­ Weather on Urban Heat Islands and Air Pollution. Water, Air, derstorm Winds, Frontal Winds, Chinook Winds and Valley Soil Pollut., Vol. 9, 53-67. Winds. Univ. of Alberta, Dep. of Geography, Edmonton, Alta. 1978/4 Wilson, H.P. Chinook Airflow. In: Essays on Meteorology 1986/3 Nkemdirim, L.C. Chinooks in Southern Alberta. Some and Climatology, KD. Hage and E.R. Reinelt (Eds.), Univer­ Distinguishing Nocturnal Features. J. Climatol., Vol. 6, sity of Alberta Press, Edmonton, Alta., pp. 387-397. 593-604.

56 Chinook Summer/Ete 1987 WEATHER MAP #1 JULY 8, 1987 1200 GMT

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'HLX 28 110 ~OO- (27) '4 HOT AND COOL JULY BREEZES Weather Map Series, July 8 to 14, 1987 by Hans VanLeeuwen

The month of July can typically be a The following activities are suggested: Many other interesting features can scorcher on the eastern palt of the be observed, such as the higbest tem­ continent. Early July 1987 was no 1) Analyse the temperatures and dew peratures recorded on the maps, the exception - Plenty of hazy sunshine, points at intervals of 2°C. areas of showers and thunderstorms, afternoon thunderstorms, early morn­ 2) Note the high moisture content of the the fog reported by ships over the cooler ing fog, high afternoon temperatures air over the area; the higher the dew waters south of Nova Scotia and New­ and very high relative humidities! point, the higher the amount of foundland, and by stations along coastal The series commences with the 1200 water vapour in the air (measured in areas. GMT (0800 EDT) map (#1) of July 8. grams of water vapour per 1000 In order to carry out a meaningful High temperatures and reduced visibili­ grams of dry air). analysis of the weather data plotted on ties in mist can be observed particularly 3) Notice the higb relative humidities. each map, the coded infOl"IDation must around and south of the Great Lakes. as indicated by the temperatures be understood. A previous issue of The July 10 situation is shown for 1200 being very similar to the dew points Chinook (Volume 8, Number 2) con­ GMT and 1800 GMT (1400 EDT) on Maps (for instance, on Map #1: the tem­ tains a detailed explanation of the #2 and #3, respectively. Nothing really perature of 23°C and dew point of synoptic map plot and also a list of significant had changed. The 1200 GMT 21°C at Toronto, Ontario). pUblications recommended for reading. situation on July 14 is entirely differ­ 4) An isobaric analysis with isobars If a copy of the above issue is not avail­ ent. A low-pressure system is moving drawn at 4-mb (or O.4-kPa) intervals able one can be obtained by mailing a through eastern Ontario with a cold will indicate the southerly flow off stamped, self-addressed envelope to the tront extending south-southwestward the Gulf of Mexico during the whole CMOS office in Ottawa, Attention: through central Pennsylvania into period, and the cyclonic circulation Editor, Chinook (Weather Map series; eastern Tennessee. Cooler air behind around the low-pressure system and Vol. 9 No.3). the front is bringing much desired relief the northwesterly flow behind the from rather uncomfortable and muggy cold front on July 14. weather.

ANSWERS TO ICEBERG QUESTIONS (Chinook Vol. 9 No.1)

1. The estimated volume of the world's It should be obvious that the mountains sometims locked within glacial ice is 2.7 x 107 km3 or2.7 x intial volume of water in ocean an ice floe, sometimes floating in 1016 mS. The surface area covered basins is an unnecessary fact in this open water. by the world's oceans is 3.6 x 108 question. 2 14 2 3. The answer IS contained in the km or 3.6 X 10 m . If we were to cover each of these square metres of 2. Sea ice develops as the high lati­ article. ocean surface with a cubic metre of tude ocean surfaces freeze. Icebergs 4. The answer is contained in the melted ice, the resulting layer would develop as high latitude land gla­ article. consume 3.6 x 1014 m'g of our total ciers deHver and deposit massive ice 5.• The volume of the water cube = ice volume. Since our total ice vol­ fragments into adjacent seas. The 6 3 16 3 1.0 x 10 m . ume is 2.7 X 10 m , it follows that area of polar seas covered by sea ice 3 we could create 75 such layers. Since is extensive and shows consider­ • Since 1 m of pure water has a mass oflOOO kg or 1 tonne, 1.0 x each layer has a thickness of 1 m, able seasonal fluctuation. The area 106 m3 has a mass of x 6 covered by icebergs is, by contrast, 1.0 10 ocean levels would rise 75 m if all tonnes. glacial ice were to melt. miniscule. Both types of ice move in response to wind and current. To • Since the cube of ice has a density Our calculated value of 75 m of 0.9, and since exceeds the predicted value. It create sea ice takes as little as Mass ignores the volume reduction that a single winter season. To create Volume = D----;-t-' accompanies any conversion of ice an iceberg takes centuries. Newly enSI y the volume occupied by this ice = into water. It also ignores the fact formed sea ice is saline. With time, 6 3 that if ocean water volume were to its salinity decreases. Iceberg ice 1.lx 10 m . increase, ocean sizes would in­ contains fresh water. On the ocean­ • While the conversion of water to crease as well. The amount of such ic landscape, sea ice appears as a ice changes the volume of the ice, it does nothing to its mass. It is an increase would be significant white plain interrupted periodi­ 6 since a substantial quantity of the cally by low ridges and open water. still 1.0 X 10 tonnes. world's land surfaces are at present Icebergs, on the other hand, appear just above sea-level. as prominent block or pinnacled Continued on page 64

61 WIND EROSION OF SOILS ON THE CANADIAN PRAIRIES by Barry Grace

Wind erosion of soil has been a major problem throughout smaller than 0.1 mm, the process of suspension may also be the history of agriculture on the Canadian Prairies. For very important. These small dust particles, once dislodged, ages, prairie soils were protected from the wind by a tight are lifted into the air and carried in suspension creating dust grass sod. Soil erosion by wind occurred soon after the land clouds. While some of these particles may only be carried was broken and converted into tilled fields. With the upward in the atmosphere a few metres or tens of metres, adoption of summer fallow tillage practices in the late 1800s others are carried to great heights and may be transported prairie farmers soon saw the winds blowing their topsoil hundreds of kilometres. They return to the surface only away. By 1914, drifting was extensive throughout the when the wind subsides or when the rain washes them out of chinook belt in southern Alberta where high winds are the the atmosphere. rule in the fall, winter and spring. It was here that the The actual velocity and turbulence of the wind near the frequent outbreaks of wind erosion led to the development ground depends on the nature and the heights of the surface and widespread use of strip farming about 1918, and blade irregularities. The intensity of the turbulence varies directly plowing and trash-cover tillage in the mid-thirties (see The with the roughness of the ground surface and inversely with Early History of Climate and Agriculture on the Canadian the height. The wind neal' the ground, in fact, is character­ Prairies to be published in a future issue of Chinook.) ized by eddies of extremely variable velocity moving in all Soil erosion by wind is caused by wind blowing across an directions. This eddying, or turbulence, is what makes soil unprotected soil surface that is dry, loose and finely erode. Erosion of soil by non-turbulent air flow has never granulated. The loss of soil by wind involves two processes: been recorded. Atmosphereic turbulence has a considerable detachment and transportation. The force of the wind, or the tendency to increase the surface speed and hence the transfer of momentum by the wind to a surface, results in momentary frictional force of the wind against the gJ·ound. some detachment of tiny soil grains (0 .1 to 0.5 mm). When Little can be done to reduce turbulence, but the surface the wind is laden with small soil particles, however, its speed can be reduced by various measures. Even a slight abrasive action is greatly increased. The impact of these reduction in wind speed near the ground produces a small, rapidly moving particles of soil dislodges other relatively great reduction in the amount of soil erosion. The particles from the soil surface. reduction of surface wind speed therefore should be one of the Once detached, soil particles are transported in three main main principles for controlling wind erosion. For example, ways: saltation, soil creep and suspension. The first and most stubble mulching, created by permitting residues of crops to important, saltation is the movement of soil by a series of remain standing in the field so as to increase the surface short bounces along the ground surface. The particles roughness and extract momentum from the wind, reduces remain close to the surface as they bounce, seldom rising the wind speed at the surface and hence blowing soil. more than 20 or 30 cm. Soil creep is the rolling and sliding of One area especially prone to wind erosion is the chinook larger particles (0.5 to 1.0 mm) along the surface. 'rhe belt of southern Alberta. Here the weather associated with process of saltation enhances soil creep since the bouncing the high frequency of chinooks causes considerable loosen­ small particles strike the large ones on the surface and ing and structural disintegration of the soil surface. accelerate their movement along it. In the majority of soils, Alternating wetting/drying and freezing/thawing cycles rnostdrifting occurs by these first two processes. However, in tend to break down the soil aggregates into granules that are fine-textured soils having a significant portion of particles highly erodible by the wind. Climate directly influences

Strip farming introduced in the early 1900s in southern Alberta is The processes of saltation and soil creep account for most soil one of the most effective methods of controlling soil drifting. drifting.

62 Chinook Summer/Ete 1987 ] f­ I C!l iii I

o~------WIND SPEED Figure 1 Profile of wind speed with height. Soil drifting in southern Alberta. wind erosion in two ways. The average wind speed for a region is a primary factor in determining soil loss as is the quantity and frequency of rainfall and the rate of drying of Monthly frequency (%) of wind speed for Kenyon Field Airport, the soil surface. A moist soil is not eroded by the wind. Since Leth~ridge, Alberta (data courtesy of Environment Canada) temperature, precipitation and wind speed all affect soil moisture and wind erosion, a climatic wind erosion factor Wind Speed (kmlh) has been developed that incorporates both the average wind Month speed and soil moistw'e for a region. The local wind erosion Calm 1-20 21-45 46-75 >75 factor that characterizes the erosive potential of the climate has been calculated as "high" for southern Alberta. January 4.5 52.4 32.0 10.1 0.9 The rate of wind movement, especially gusts having February 5.2 47.9 34.8 11.4 0.6 0.2 speeds greater than average, will influence erosion. Tests March 3.3 50.8 38.6 7.1 April 1.9 47 .2 43 .6 7.0 0.3 have shown that wind speeds of about 20 to 45 k.mIh, depending on moisture content, are required to initiate soil May 2.4 53.2 39.6 4.4 0.3 2.2 54.1 38.9 4.6 0.2 movement for typical prait'ie soils. The quantity of soil June carried by the wind increases rapidly at speeds above 20 July 2.7 63.7 31.8 1.7 0.0 August 3.1 63.2 31.4 2.3 0.1 kmIh. It should be noted, however, that these tests were conducted in wind tunnels where the wind speed was September 2.4 56.6 37.0 3.9 0.1 measured at a height of only 15 cm. This does not mean that October 2.4 43.1 45.8 8.3 0.4 when we hear of wind speeds of20 km/h we can expect to see November 3.3 45.9 40.4 9.8 0.6 4.2 46.0 36.7 12.4 0.7 soil drifting. Wind speed varies with height with winds December speeds decreasing close to the surface (Figure 1). Reported Mean 3.1 52.1 37.6 6.9 0.4 wind speeds are usually recorded at a height of 10 m. To achieve a wind speed of 20 kmlh at 15 cm, a wind of about 45 kmfh at 10 m would be required. Wind speeds in excess of 45 distance downwind until, if the field is long enough, the flow kmJh occur in the Lethbridge area a little more than 7 per reaches a maximum that the wind of a particular speed can cent of the time, with an annual average of640 hours (see the support. The intensity of erosion increases with duration of accompanying table). exposure owing to an increase in the amount of erodible On flat, unprotected eroded fields, the rate of soil flow is fractions of soil produced by abrasion, or to the wearing away zero on the windward or leading edge and increases with of non-erodible clods and surface crusts by the impact of particles through the process of saltation. On a small isolated area, such as a narrow strip of fallow land at right angles to the wind direction, the intensity of Direction of wind erosion is rapid at first, diminishes with duration of Zone of removal exposure, and ceases as soon as the height and number of non-erodible soil fxactions become sufficient to shelter the erodible fractions from the wind. The shorter the length of the erodible area, the less the amount of abrasion and hence the lower the rate of soil movement. Over rolling terrain, where the slopes are relatively short, the wind speed is highest at the top of the knolls. Here the potential for soil removal from the crests is much greater. Small reverse eddies on the windward side of a knoll tend to Figure 2 CrosB-section of a ridge indicating zones of soil removal, move soil backward and downward, whereas lee eddies accumulation and direction of movement when the wind blows at deposit soil on the lee side of the hill and form overhangs right angles to the ridge (adapted from Armbrust et aI., 1964). along the ridgeline (Figure 2). 63 There appear to be irregular cycles of severe wind erosion Armbrust, D.V.; W.S. Chepil and F.H. Siddoway, 1964: Effects of that reflect cycles of the weather. Recurring periods of Ridges on Erosion of Soil by Wind. Soil Sci. Soc. Amer. Proc. 28, pp. drought and high winds have worsened erosion. The general 557-560. frequency of occurrence of periods of high wind and low Grey, G.H., 1967: Men Against the Desert. Western Producer precipitation can be predicted from past records, but the Prairies Books, Saskatoon, Sask., 250 pp. times when they will occur cannot be predicted. Constant Palmer, A.E. (No Date): When the Winds Came, 57 pp. preparedness for such periods is therefore essential if wind erosion is to be controlled. Barry Grace is a Research Scientist specializing in Agricultural SUGGESTED READING Meteorology at the Agriculture Canada Research Station in Anon., 1966: Soil Erosion by Wind. Canada Department of Lethbridge, Alberta. Agriculture Publ. 1266, 26 pp. Photograph credits: Lethbridge Research Station Archives.

RESUME L'erosion eolienne des sols s'est averee un probleme sol); reptation du sol (roulement et glissement des plus grosses majeur tout au long de l'histoire agricole des Prairies canadiennes. particules a la surface du sol- 0,5 a 1 mm); et suspension (pour les En general, l' erosion est causee par des vents qui soufflent a la surface particules mesurant moins de 0,1 mm). La diminution de la vitesse d'un sol non protege, compose de terre meuble, seche, fine et du vent a la surface est un des principes essentiels de reduction de granule use. Deux phenomenes entrent en jeu " le detachement et le l'erosion eolienne. Les degres de vitesse du vent et de dessechement transport. La force du vent et son action abrasive, produite par les sont deux facteurs principaux d'erosion eolienne des sols. Parmi de petites particules de sol, contribuent fortement a la suppression de la nombreux elements importants, on mentionne l'intensite des rafales, couche superieure du sol. Une fois detachees de la surface, les le profil vertical du vent, le profil du terrain ( «caractere plat,,), le type particules de sol se deplacent de trois far;ons principales " saltation de sol, le contenu en eau, l'etendue et l'emplacement du terrain, ainsi (deplacement sous forme de petits bonds des particules a la surface du que l'existence de vegetation.

Answers to Iceberg Questions degree of stability possessed by that 1440 nautical miles. At a speed of Continued from page 61 object. Tipping a basketball in 200 nautical miles per hour, a water does not raise its centre of plane would take a little over 7 • The ice mass will stop sinking in gravity. Consequently, in no posi­ hours to fly the distance. the water when it has displaced a tion is it ever stable. Flat boards or 0 mass of water equal to its own 9. Along the parallel 70 N, Greenland 6 rectangular posts, by contrast, are mass, i.e. 1.0 x 10 tonnes. stable in a variety of positions. traverses approximately 33° oflon­ • Since only 1.0 x 106 m3 of ice is gitude. If these were latitudinal 6 However, if thrown into water, they required to displace 1.0 x 10 "choose" the positions that are the degrees, 33° would represent (33 x tonnes oflake water, the amount most stable. This is achieved when 60) or 1980 nautical miles. Since of ice remaining above the water the distance between consecutive 3 their broadest surfaces face upward. line is 1.0 x 10'-5 m • The stability of an iceberg is meridians decreases in accordance • Since the ice density = 0.9 and related to its shape. Tabular bergs, with the cosine of the latitude at since its shape is cubic, it follows resembling fence boards, are very which it is measured, the actual that its base will be at a depth of stable. Spherical (domed) bergs roll distance across the island at 700N slightly over 90 m. easily. is 1980 x cos 70° or 677 nautical 6. Each plot on a cumulative curve is miles. 8. In 6° oflatitude there are (6 x 60) or the sum of all previous plots added 10. Like 3 and 4, the answers to this to the current value. Therefore, the 360 nautical miles of distance. From north to south through Green­ question are contained in the arti­ last point plotted on this curve cle questions. represents the total of all items land, one traverses (24 x 60) or plotted, i.e. the total annual crop of icebergs crossing latitude 48°N. CLIMATE QUIZ The degree of slope expresses the rate of accumulation. A zero slope Match each capital city with its climate designated by the letter in the table below indicates zero accumulation. Our curve indicates the greatest accu­ Annual M~an Annual MeaD Days with Hours of mulation of iceberg crossings occurs City Temperature PJ,ecipitation Precipitation Sunshine (OC) (rom) in May. To convert the cumulative curve into a graph that indicates Charlottetown, P ,Jl).1. a 10 647 138 2191 monthly totals rather than accu­ Edmonton Alta. b 8 466 il4 2264 mulated totals, one simply sub­ Fredericton, N.B. c 2 384 111 2331 tracts from any point the value of Halifax, N.S. d 2 526 120 2321 the previous point. The resulting 12 Ottawa, Onto 6' 7 801 134 2045 numbers can then be represented Qu~bec , Que. f 4 1174 171) 1852 on a bar or a line graph. Regi.nJ\, S~ . g 0- 1109 156 1878 7. An object is physically stable if, St. John's, Nfld. h 5 1169 174 1818 when tipped, it attempts to return Toronto Onto S 1282 153 1885 to its original position. When a Victoria, B.a. j 5 1514 217 1497 stable object is tipped, its centre of WbitehQ1'$e, Y.T. k - 1 261 120 184ll gravity rises. The distance the Winnipeg, Ma~. I - 5 26'7 121 ,};277 centre of gravity rises as the object 'Y'ellowknife, N.W.T. m 7 875 137 2009 is tipped is an expression of the Answers will be supplied in the next issue of Chinook. 64 Chinook Summer/Ete 1987 WINTER OF 1986-87 IN REVIEW by Amir Shabbar

The season produced record mildness and a meagre snowfall over western Canada but held its icy grip over the East Coast.

Canadians from the Yukon to Ontario will remember the winter (December 1986-February 1987) for its record to near-record mildness and scanty snow­ falls. In contrast, cold and stormy weather plagued Atlantic Canada and the northeastern Arctic throughout most of the winter. Southern Ontario and southern Quebec enjoyed record amounts of sunshine in February.

TEMPERATURE A vast stretch of the Nation from the Yukon to the St. Lawrence Valley in­ cluding Franklin District of the North­ west Territories enjoyed a warmer than normal winter. The temperatures were 6 to lOoC above normal over the Prairies and the Yukon. The southwestern Yukon had the largest departures from normal, more than 10°C above normal. Balmy weather produced 3 consecutive months of record warmth. Winnipeg enjoyed its Lack of snow cover allowed wind-driven soil erosion on many southwestern Prairie farms. mildest winter ever (-9.4°C) and north­ western Ontario one of its warmest winters. At Edmonton, this winter ranked as the second warmest in 107 whopping seasonal total of 472 cm, deteriorated roads could not support years (-4.1 °C). Mild air extended into nearly twice its normal of270 cm. Over heavy machinery. The mild weather the Yukon and the District of Macken­ the Great Lakes and the St. Lawrence also hastened the blossoming of daffo­ zie producing the second mildest winter Valley, snowfall amounts were 50 to dils in British Columbia, and growers at Whitehorse ( -7 .O°C) and the mildest 90% of the long-term averages. had to spray growth retardant on them ever at Yellowknife (-18.2°). In con­ to delay blooming until the traditional trast, Atlantic Canada and the north­ SIGNIFICANT CLIMATIC Easter period. Benignly mild weather eastern Arctic experienced month after IMPACTS together with below normal snowfall month of abnormal cold. The tempera­ Month after month of record mildness hampered fur trapping and adversely tures were nearly 5°C below normal took the bitter sting out of the Prairie affected the sport of dog mushing in the over Baffin Island, where a prolonged winter. Daytime temperatures soaring cold spell extended into its ninth month near the 17°C mark lured residents of by the end of February. southern Alberta to the beaches in the middle of February. The mild weather PRECIPITATION produced the warmest January in at Much of Canada had a drier than least 8 Prairie locations. Most of the normal winter. Precipitation was less southwestern Prairies was free of snow than half of normal over most of during the winter. The lack of adequate Alberta, southeastern British Colum­ snow cover permitted wind-driven soil bia and parts of southern Quebec. erosion on many farms. On a positive During December, Grande Prairie had note, cattle ranchers realized a substan­ its least snowfall, 0.7 cm; at Calgary, tial saving in animal feed costs since the 37 -cm seasonal accumulation was their cattle could graze on the snow-free less than half the normal of97 cm. Both range land. the east and west coasts of Canada had Throughout interior British Colum­ more than their normal share ofprecipi­ bia, a prolonged mild spell contributed tation. Snowfall was particularly heavy to soft and muddy bush-logging roads. over Newfoundland. Gander received a Logging operations suffered since the 65 SUBSCRIPTION ORDER

I Please enter my subscription to Chinook for one year (1988, 4 issues) at the following rate I I (ple3lle check one): I THE CANADIAN MAGAZINE OF I o CMOS Member $10.00 I o Non-member Individual $12.00 WEATHER AND OCEANS I o Institution $15.00 I WHAT? Chinook is a popular maga­ zine concerned with two major compo­ j N9me ------~'~PL~EA~.~E ~.~~~~.,.------nents of the Canadian environment - the I I Add r~'------~(~~~A-L OO~". , atmosphere and the oceans. It is pub­ I I School or University (if student)'______lished quarterly by the Canadian Mete­ I orological and Oceanographic Society I (CMOS). i Mail with payment to CMOS, Suite 903, 151 Slater Street, Ottawa, Ontario KIP 5H3. Features in Chinook include articles, ! ThiB iB a 0 NEW order; a 0 oubocription renewal. $ ______iB encloBed. I weather summaries, interpretations of I Back issues: $5.00 each; 10 or more: $4.00 each I satellite and other photographs, and ------news and notes. These appear in the language submitted (English or French). • marine-recreation, sports and tourism On retrouve dans Chinook des arti­ In addition, summaries of all articles operators and enthusiasts cles, des sommaires du temps, des appear in the other language. I aviators interpretations de photos satellitaires et • amateur observers of natural pheno- autres, des articles d'actualite et des WHY? The aims of Chinook are mena notes. Ces articles paraissent dans la • to increase public awareness of mete­ • speCialists in other sciences langue originale, Ie francais ou I'ang­ orology and oceanography in Canada • environmentalists lais ; tous les resumes sont rediges dans and of their modern scientific and I'autre langue. technological aspects and achieve­ HOW? Subscriptions to Chinook may ments be ordered using the handy form POURQUOI? Chinook vise a : • to stimulate public interest in and above. • eveiller la curiosite du public en ce understanding of the impact of cli­ qui a trait aux aspects de la meteoro­ mate, weather and oceans on Canad i­ logie et de I'oceanographie au Canada an society and economics LA REVUE CANADIENNE DE LA et a I'inforrner des realisations scienti­ • to infomi'yanadians about the educa­ METEO ET DES OCEANS fiques et technologiques d'aujourd'hui; tion, information and interpretative • stimuler I'interet du public et I'aider QUOI? Chinook est une revue de services available to them on climate, mieux comprendre les elfets du vulgarisation qui traite de I'atrnosphere a weather and oceans climat, du temps et des oceans sur la et des oceans - deux des importants societe et sur I'economie du Canada; WHO? Features in Chinook are cho­ elements qui composent I'environne­ • renseigner les canadiens sur les ser­ sen to appeal particularly to ment canadien. Chinook est publie tous vices d'education, d'information et d'in­ • secondaryschoolandcommunitycol­ les trois mois par la Societe canadienne terpretation qui leurs sont disponibles fege students de meteorologie et d'oceanographie et qui traitent du climat, du temps et • farmers, fishermen and foresters (SCMO). des oceans. QUI? Les articles choisis pour Chinook vise a interesser notamment : • les etudiants d'ecoles secondaires et ABONNEMENT de colleges communautaires Je d6sire m'abonner 1\ Chinook pour une annee (1988, 4 num6ros) au tarif 8uivant • les agriculteurs, pecheurs et agents (veuillez cocher): forestiers o Membre de la SCMO 10,00 $ • les exploitants d'etablissements de o Non-membre 12,00 $ nautisme, de sports et de tourisme, et o Inatitution 15,00 $ les amateurs des ces activites Nom------~Ik~N~M~A~JU~~~U~L.=S~.V~.•~ . I~------• les aviateurs • les observateurs amateurs de pheno­ A Adr08Ra.------:-:(c:-o:-:.~,-:~=A-.L) menes naturels

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