Chinook (wind)
The Chinook [ ʃɪˈnʊk, tʃɪˈnʊk ] is a warm fall wind on the east side of the Rocky Mountains in the inner west of North America. Here the Great Plains and the Canadian Prairies meet several mountain ranges. The meteorological events of the Chinook wind are similar to the foehn in the Alps . The Rocky Mountains are about the same height as the Alps, but the Chinook is even drier and warmer than the Föhn.
The origin of the name Chinook in Alberta and Montana was mistakenly translated as snow-eater (English snow-eater ). However, it is actually the name of the Chinook people who lived in the northwestern region of the USA along the lower Columbia River . Chinook was originally the name given to the humid, warm wind in the Pacific Northwest that blows from the ocean into the interior.
A strong chinook wind can completely dissolve a thirty centimeter thick snow cover within a day, whereby the snow not only melts, but also partially sublimates in the dry wind .
It has been observed that chinook winds often increased winter air temperatures from −20 ° C to +10 ° C to +20 ° C within a few hours or days. Then the air temperature fell back to the initial level. The largest recorded temperature change within 24 hours due to the chinook wind was measured on January 15, 1972 in Loma (Montana) , with the temperature rising from −48 ° C to +9 ° C.
At the 1988 Winter Olympics in Calgary, the Chinook caused the temperature to rise from -30 ° C to +12 ° C and wind speeds of up to 120 km / h overnight , so that numerous events had to be canceled.
Canada
Chinook winds are the most common winds in southern Alberta , particularly in a strip that stretches from the town of Pincher Creek through Crowsnest Pass County to the town of Lethbridge . Here there are chinook winds an average of thirty to thirty-five days a year. Chinook winds usually do not occur further north of Red Deer Town (53 degrees north latitude).
However, the occasional occurrence of chinook winds can also be observed further north - to Grande Prairie (55 ° north latitude) in northwest Alberta and Fort St. John in northeast British Columbia . But chinook winds also occasionally occur far in the south of the USA - for example in Albuquerque ( New Mexico ). In general, chinook winds are not as common further south in the US.
In southern Alberta, there is very little or no snow for the majority of winters. In Calgary there is snow during the Christmas season to 56 percent, while in Edmonton are 86 percent. In Canada, only the west coast of British Columbia and southern Ontario have fewer white Christmas days than southern Alberta.
In Lethbridge, gusts of chinook winds can be stronger than hurricanes with their wind speed of 120 km / h. On November 19, 1962, a particularly strong Chinook with gusts of up to 171 km / h was registered here.
In 1962, the temperature in Pincher Creek rose by 41 ° C in one hour, from −19 ° C to 22 ° C, and trains have already derailed due to Chinook winds.
In winter, the wind can blow the streets with a blanket of snow over a meter thick and make them disappear . Empty semitrailers on Highway 3 ( Crowsnest Highway ) and other roads in southern Alberta have already been overturned by strong gusts of the Chinook winds.
Calgary gets a lot of chinooks because the Bow River valley in the Canadian Rockies, west of Calgary, looks like the funnel of a natural wind tunnel that guides the chinook winds.
In February 1992 Claresholm in Alberta experienced one of the highest ever recorded February temperatures in Canada with 24 ° C.
Chinook and arctic air masses
At the height of winter, the Chinook occasionally collides with arctic air masses.
For example, the temperature in Lethbridge is −20 ° C, while it is only 77 kilometers further south in Cardston (Alberta) at +10 ° C.
This limit of the temperature difference can remain stationary or shift back and forth so that there can be a warm morning, a bitterly cold afternoon and a warm evening. The collision of the warm air mass in the west and the cold air in the east is often accompanied by fog.
For example, Cardston Main Street was covered in fog, while the western half of the city had mild weather with melting snow and the eastern half of the city was bitterly cold.
In Calgary there have been winters in recent years, when the airport in the northeast of the city measured a temperature of −20 ° C, while it was +7 ° C in the southwest.
Chinook bow
One of the most striking features of the chinook is the chinook arch . This is a band of stationary stratus clouds, which is caused by air waves over the mountains - triggered by the orographic uplift of the air masses.
The chinook bow can occasionally resemble a threatening storm cloud, but it rarely brings rain or snowfall. The chinook arch can create impressive sunrises or sunsets.
What is remarkable is the play of colors on a chinook bow, where the hues change over the course of the day. It starts in the morning at sunrise with yellow, orange, red and pink, then changes to gray tones and shortly before sunset to pink-red and then to orange-yellow tones.
Origin of the Chinook
The chinook is a hair dryer , a wind in the rain shadow of a mountain. It arises from the adiabatic heating of air masses, which have rained down a large part of their air humidity as a result of the orographic uplift on the windward side of the mountain range.
As a result of the different adiabatic atmospheric temperature gradients - the dry adiabatic temperature gradient (9.81 K / km) is greater than the wet adiabatic temperature gradient (4 K / km to 9 K / km) - the flowing air mass on the leeward side of the mountain range becomes warmer than the one on it the windward side at the same height.
The humid winds from the Pacific, also called Chinook, are deflected upwards by the mountains (orographic uplift), cool down, the humidity condenses and falls as precipitation (rain or snow). As the air cools (3.5 ° F / 1000 ft) with a wet adiabatic temperature gradient of 5 K / 1000 m altitude gain, it warms up with a dry adiabatic temperature gradient of 10 K / 1000 m (5.5 ° F / 1000 ft) when it sinks again on the other side of the ridge.
The turbulence of the high winds can also prevent the normal night temperature inversion on the leeward side of the mountains, the night temperatures then remain high there.
Quite often, when there is heavy rainfall on the west coast, the windward side of the Rocky Mountains is affected by heavy snowfall - the rising air mass gives off its condensed humidity - and the lee side, the province of Alberta, is then affected by the Chinook.
The predominant cloud pattern consists of the chinook arch or a bank of clouds (also known as cloud wall ) that obscures the west side of the Rocky Mountains. It looks like an approaching storm, but it doesn't spread further east.
Manyberries Chinook
Often times , at the end of a cold spell, the chinook is preceded by a Manyberries chinook . This southeast wind is after the small village of Manberries (location: 49 ° 24'06 "N 110 ° 41'38" W; now a hamlet ) in Forty Mile County No. 8 in southeast Alberta, where the wind probably originated. The Manyberries Chinook can blow very strongly and bring great cold and heavy snowstorms with it. When the actual Chinook arrives, the wind turns southwest and the temperature rises sharply.
The Chinook in the Pacific Northwest of Canada
The term chinook is also used in British Columbia . Here it was coined by the Indian tribes on the Pacific coast. The term first came to Alberta through fur traders.
Such winds are extremely humid and warm and come from the southwest. They are also known as the Pineapple Express (German Ananas Express ), as their origin is in the subtropics , roughly in the region around Hawaii . The air masses that coexist with the west coast Chinook are stable . Therefore the wind is only slightly gusty with only slight air movements in protected areas. In open areas there are often light strong winds during a Chinook , storms are rather rare. Most of the storms in the region occur, regardless of the Chinook, when a fast jet stream from the west causes air masses from temperate latitudes and those from arctic latitudes to collide.
If an arctic air mass is stationary over the coast and a chinook wind hits it, then the tropical moisture of the chinook is suddenly cooled and snowfall occurs, which only occasionally reaches down to sea level. The cold and the resulting snowfall during the Chinook only last a few days while the wind comes from the southwest. After that, the snow melts relatively quickly within a week.
The effects inside British Columbia are exactly the opposite during a chinook. In rainy periods, most of the high humidity on the windward side of the mountains is rained off or snowed off before the air masses reach the area of the Fraser Canyon ( Fraser River ) and the Okanagan Valley with the Okanogan River and the Thompson River . The effects are similar to those of the Chinook in Alberta, although not as extreme. The reason for this lies partly in the fact that the Okanogan River is relatively warmer than the prairie provinces and because the mountains between Kelowna and Calgary additional precipitation deduct .
If the Chinook brings snow for them during a cold spell on the coast, then there is clear but very cold weather in the interior of Canada. The subsequent snowmelt is more of a warm period than due to the rain.
The term chinook is common among fishermen in the British Columbian coastline. The term is also used on Puget Sound in Washington State .
The contrast to the Chinook in British Columbia and in Pacific Northwest are easterly winds - cold continental air masses that come from the Interior Plateau , cross several river valleys and blow over the Coast Mountains towards the Pacific coast. These winds are called squamish in some areas , after the city of Squamish , British Columbia. The wind blows along Howe Sound (49 ° 33'N 123 ° 16'W), which flows into the Strait of Georgia . Howe Sound is the settlement area of the Squamish tribe . In Alaska, this type of easterly wind is called the Williwaw .
Pronunciation of the word chinook
In British Columbia and parts of the Pacific Northwest is Chinook , t 'with the initial sound , pronounced [ tʃɪnʊk ]. In the center of the US state of Washington, in Alberta and the rest of Canada, on the other hand, with an initial 'sh', [ ʃɪˈnʊk ], which corresponds to the French pronunciation. This different pronunciation probably stems from the fact that the mestizos employed by the Hudson's Bay Company and familiar with the Chinook people and their lands introduced the name Chinook east of the Cascade Range and the Rocky Mountains along with their own ethnicized pronunciation.
Historical records indicate that the word was originally pronounced with a 't' before it migrated to the areas east of the Rocky Mountains . The original pronunciation of Chinook on the coast is [ tʃɪˈnʊk ], while east of the Rocky Mountains it is pronounced [ ʃɪˈnʊk ].
Native American legends
According to a legend of the Lilwat people , a subgroup of the St'at'imc tribe , the girl Chinook-Wind married the glacier and moved to live with him in what is now known as the Birkenhead River area. It longed for its warm home on the coast and sent its people a message asking them to get it. They then appeared to him in a vision in the form of snowflakes to tell him that they would come and get it. His people then actually came in large numbers and fought the glacier for Chinook wind . They finally overpowered him and the girl went home to the coast with her people.
While it is ostensibly a family and tribal story, it appears to be a parable about the typical weather pattern of southwest winds. They bring snow first, then rain. The parabola also appears to be referring to the melting of a glacier, particularly the Place Glacier near Gates Lake (location: 50 ° 29'00 "N 122 ° 38'00" W) in the borough of Birken, British Columbia , Location: 50 ° 29′00 ″ N 122 ° 37′00 ″ W).
This legend also reflects the migration of a people to another area. Depending on how the legend is read and embellished, it could also have been a war.
horticulture
The frequent winter thaws caused by the Chinook create problems for horticulture in its catchment areas in the Great Plains . The Chinook harms the plants more than it benefits them. The plants end their hibernation with persistent chinook winds, which can be clearly seen. At least their resistance to the cold is reduced, even if they seem to remain in hibernation.
In both cases, the plants are no longer as resistant to a later cold snap. Many plants that do well in Winnipeg , where a consistently cold climate ensures that the plants remain dormant, do not grow well in Alberta's Chinook Belt.
Examples are the American linden , some apple varieties and raspberries, rock pears and fire maple . Trees in areas affected by the Chinook are known to be smaller and grow more slowly than trees in unaffected areas. This fact can be attributed to the interrupted winter dormancy of the plants.
health
According to a study, the number of migraines caused by the Chinook (often referred to as Chinook headache ) is expected to increase in the population.
The chinook also often leads to irritability and drowsiness . To larger cities such as Calgary, the Chinook at the height of winter can flow away, so the polluted air above the city on cold air encapsulate and inversion - Smog lead.
Then it is cold on the ground, while it is considerably warmer at the level of the upper floors of the so-called skyscrapers and on the surrounding hills.
folklore
There are three well-known children's fairy tales that revolve around the chinook and are particularly well known in southern Alberta:
- A man rode his horse to the church. When he got there, the church was snowed in and only the church tower was sticking out of the snow. So he tied his horse to the church tower, where other horses were already tied. He attended the service and when he came out the Chinook had melted the snow and the tethered horses were hanging high up on the top of the church tower. The story has a strong analogy to the story of Münchhausen's trip to Russia and St. Petersburg by the lying baron Münchhausen .
- A man was driving his snow sled into town when he was surprised by a Chinook. He urged his horses to be as fast as the chinook wind. And while the horses sank up to their belly in the snow at a trot, the sledge runners slid deeply sunk through the mud. However, the cow, which was tied to the back of the sled, was raising dust as it ran.
- A man and his wife were out during a chinook. The woman was dressed warmly, while the man wore only summer clothes. When the couple returned home, the man had chilblains and the woman had heat stroke.
records
Loma, in Chouteau County , Montana , has the largest recorded temperature difference in a 24-hour period. On January 15, 1972, the temperature rose from −48 ° C to +9 ° C, i.e. by 57 ° C.
The Black Hills in South Dakota saw the fastest temperature rise. On January 22, 1943, the temperature at 7:30 a.m. Mountain Standard Time in Spearfish, South Dakota was −20 ° C. An emerging chinook wind brought the temperature to + 8.3 ° C within two minutes, a difference of 28.3 ° C. By 9 a.m. the temperature had risen to 12 ° C. The chinook suddenly stopped and the temperature dropped to −4 ° C within 27 minutes.
As mentioned above, a wind speed of 171 km / h was measured during a Chinook in Alberta. These high wind speeds occur west of the 100th longitude west, in the Great Plains of Canada and the United States. On rare occasions, chinook winds have reached and even crossed the Mississippi River from the eastern slopes of the Rocky Mountains .
Chinook and Hair Dryer in the United States
For chinooks in the United States, meteorologists and climatologists use the more precise term foehn . Whether called Chinook and Föhn, this wind can occur on the leeward side of most mountain ranges.
In western North America, especially in the Rocky Mountains region, the term Chinook winds is predominant . Chinook winds are relatively common, especially in Montana. They occur across the state in the winter months, and come from the Rocky Mountain Front in particular .
Chinookwinde is also available in the region around Cook Inlet in Alaska . The air mass moves over the Chugach Mountains between Prince William Sound and the Portage Glacier . Many Anchorage residents mistakenly believe that this warm wind, which melts snow in mid-winter and leaves roads covered in slush, comes from Hawaii . This common misconception stems from their assumption that the warm wind has the same place of origin as the similarly warm coastal wind in southern British Columbia and in the US states of Washington and Oregon .
East of the Rocky Mountains, in the states of the Great Plains (e.g. South Dakota ), there are also winds that resemble the Chinook, especially east of smaller mountain ranges (e.g. the Black Hills ).
Chinooks also occur in Colorado , particularly near Denver . Here the wind blows over the front range and within a few hours leads to a rise in frosty winter temperatures to around +10 ° C.
Chinook winds are also found near other cities in the Rocky Mountains, such as Billings , Salt Lake City, and Albuquerque .
Individual evidence
- ↑ CBC / Radio Canada : Extreme weather . 28 Feb 1988
- ↑ http://www.ec.gc.ca/meteo-weather/default.asp?lang=En&n=642F4B39-1
- ↑ Archive link ( Memento of the original from March 23, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ C. David Whiteman: Mountain Meteorology: Fundamentals and Applications. Oxford University Press, 2000, ISBN 978-0-19-513271-7
- ↑ The Indian and the South Wind, p. 156 ( Memento of the original dated May 30, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , in: Robert Hendrickson: The Facts on File Encyclopedia of Word and Phrase Origins. , Checkmark Books, New York 2000, ISBN 978-0-8160-6966-8
- ^ William Fraser Tolmie : Comparative Vocabularies of the Indian Tribes of British Columbia with a Map Illustrating Distributions Dawson Brothers, 1884. Example of the original pronunciation of Chinook
- ↑ Randy Bouchard, Dorothy Kennedy: Lillooet Stories. Volume VI, Number 1, Victoria Sound Heritage, 1977
- ^ Chinooks and Health , University of Calgary , Department of clinical neurosciences, 2008
See also
- Winch and wind systems
- Katabatic wind
- Santa Ana Winds
- Mistral (wind) (France)
- Bora (wind) (Adriatic Sea)