CHINOOK WINDS by S Ellis https://padlet.com/alltechpm/rsxtxbk1kjv3 en-us 2019-04-10 13:52:42 UTC 2025-10-15 01:16:34 UTC hello@padlet.com What are Chinook Winds? alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350357829 Chinook winds are warm, dry, gusty, westerly wind that blows down the Rocky Mountains into the mountains' eastern slopes and the western prairies.   

]]> 2019-04-10 13:56:01 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350357829 Where does the Chinook Winds occur in Canada? alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350400638 The area shown in red in the map below has the most intense Chinook Winds in Canada which is the City of Lethbridge, Alberta and surrounding areas.  The area in orange which includes the City of Calgary and Medicine Hat are significantly affected. The area in yellow is affected, but to a lesser extent.  ]]> 2019-04-10 15:18:58 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350400638 How does the Chinook occur? alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350406968 A chinook occurs when the cold air layer is shallow enough that it is completely dammed behind the mountain range, then only the warmer-than-normal air at middle altitudes can flow over the mountains. The suction behind the mountain brings the warm air down toward the valley. As this air descends, it is compressed by the increasing air pressure as it gets to lower altitudes, causing the descending air to warm at about 10°C for each kilometer is descends. (This dry adiabatic lapse rate  is actually 9.8°C/km). The adiabatic lapse rate is the rate at which dry (i.e. unsaturated) air cools when rising adiabatically through the atmosphere as a result of the utilization of energy in expansion.

This phenomenon of a warm, dry, downslope wind is a Chinook (it's called a Foehn in Europe). These winds can be strong enough to blow the roofs off of houses, so they can be a flight hazard and a landing/takeoff hazard.

]]> 2019-04-10 15:30:08 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350406968 Chinooks can occur another way...... alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350412378 They can also happen even without the initial cold-under-warm layering of air. For this to occur, the air approaching the mountain range must be humid, such as air approaching from over the ocean or large lakes. As this humid air is forced upward over the mountain range, the air cools, causing water vapor in the humid air to condense into water droplets. Much of this liquid (or solid) water falls out on the windward side of the mountain range (see the sketch below).

The condensation process releases latent heat, causing the air to not cool as fast with increasing altitude as it normally would. However, when this air descends down the lee side of the mountain, it warms at the dry adiabatic lapse rate, causing it to be much warmer at location 6 in the diagram below than when it started at location 1. The net result is a warm, dry, downslope wind at location 5 on the sketch. When this happens in winter with snow on the ground, the warm dry air can evaporate the snow, nicknamed a "snow eater".

]]> 2019-04-10 15:40:20 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350412378 How does the Chinook develop in Western Canada? alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350415866 Chinook winds develop in Western Canada when warm, moist air blows from the Pacific Ocean in the northwest region of North America toward the Rocky Mountain range. The air mass cools as it climbs the mountains, bringing rain or snow to the peaks. The air mass, now dry after releasing its moisture in the mountains, warms as it moves down the eastern side of the mountains. The air mass warms rapidly, eventually becoming warmer and drier than the original air mass coming from over the Pacific Ocean. When the winds suddenly change direction toward the west or southwest, the Chinook winds begin with rapidly increasing speeds.

]]> 2019-04-10 15:46:53 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350415866 Does the Chinook occur year round? alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350422506 The Chinook Winds occur in every season, but it is more distinctive and numerous in the winter, when the unseasonable warming it brings differentiates it from the normal cold winter weather.  The chinook can bring drastic changes in weather during the winter months resulting in snow thaws throughout the winter season.   The change can be dramatic. On January 11, 1983, the temperature in Calgary rose 30°C (from -17°C to 13°C) in 4 hours, and on February 7, 1964, the temperature rose 28°C, and the humidity dropped by 43 percent.]]> 2019-04-10 15:58:56 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350422506 Chinook Arch alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350426692 2019-04-10 16:06:21 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350426692 Meteorologist explains Chinook Winds in Calgary alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350445272 Wild temperature swing in Calgary: -9C to +9C, here's why

]]> 2019-04-10 16:42:04 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350445272 Effects of Chinook Winds alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350462211
  • Rapid and large temperature changes 
  • Snow may melt or evaporate through sublimation
  • Loss of moisture due to significant drops in humidity
  • Rivers and Lakes may lose ice at 2.5 cm per hour
  • Strong, warm winds blow may carry sounds long distances 
    • Effects on Agriculture
    • Loss of soil moisture
    • Snow offers insulation and protection for plants/animals. This is lost.
    • Summer Chinooks can damage small plants
    • Removal of snow provides winter grazing for livestock
    • If the temperature drops rapidly following a Chinook, a crust of ice may form on the snow which makes grazing difficult and may result in injuries to animal’s legs
    • It may result in lower costs for hay and winter feed
    • Abrupt temperature changes can cause pneumonia, septicemia and shipping fever in cattle
    • Wire fences can become electrified due to the strong positive electrical charge in the air. Cattle have been electrocuted in this way 
    ]]>     2019-04-10 17:11:51 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350462211     alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350483758 2019-04-10 17:52:17 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350483758 Do Chinook Winds occur elsewhere in the world? alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350487649 Although the warm winds may be called a different name elsewhere in the world, winds similar to Chinook occur all over the world. In the European Alps, they are called "Föhn Winds". In central Asia, they are called "Afganet"; in the Andes of South America, these winds are called "Puelche"; and in southern California, they are known as the "Santa Ana Winds".]]> 2019-04-10 17:59:14 UTC https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350487649 References alltechpm https://padlet.com/alltechpm/rsxtxbk1kjv3/wish/350507883
    Chinook Wind (n.d.)  Retrieved April 10, 2019 from https://en.wikipedia.org/wiki/Chinook_wind

    Mountain Nature.  (2005).  Chinooks – Warm West Winds.  Retrieved April 10, 2019 from http://www.mountainnature.com/climate/chinook.htm

    Nkemdirim, L.C., (2015).  Chinook. Retrieved April 10, 2019 from https://www.thecanadianencyclopedia.ca/en/article/chinook

    Oxford University Press.  (2019).  dry adiabatic lapse rate. Retrieved April 10, 2019 from  http://www.oxfordreference.com/view/10.1093/oi/authority.20110803095732430

    The Weather Network.  (2017).  Wild temperature swing in Calgary: -9C to +9C, here's why.  Retrieved April 10, 2019 from  https://www.theweathernetwork.com/news/articles/calgary-temperatures-november-22-chinook-environment-canada/89731

    University of British Columbia (2018).  Weather for Sailing, Flying & Snow Sports.  Retrieved April 10, 2019 from  https://www.eoas.ubc.ca/courses/atsc113/flying/met_concepts/02-met_concepts/02e-shear_at_aerodromes/downslope_windstorms.html

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