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Climate Controls

The weather station used for this blog, is the Calgary International Airport. It sits at an elevation of 1,084 meters and lies in a relatively flat area.

As Calgary is a landlocked region, and predominantly a prairie region, the major climate control is the nearby Rocky Mountains. In addition, their high elevation allows the mountains to have a strong influence on their weather which leads it to be quite unstable and hard to predict. The Chinook winds (discussed earlier) that come down from the mountains can also increase temperatures dramatically for Calgary.

On a micro scale, the two major rivers that run through the city, the Bow River and the Elbow River, affect the climate by cooling the air around them. While most of the city is grassland and open area, there are parts, such as downtown,  that   is largely populated with buildings and people. This and other built up areas create an urban heat island where the temperature tends to be higher than the overall temperature of the city.

 

 

 

According to the Koppen/Geiger climate classification; Calgary is a BSk climate. The BS stands for a semiarid climate meaning that its precipitation is less than the potential evapotranspiration, and the k stands for a mid-latitude climate. Its mid-latitude cyclones (which allow the region to receive more precipitation) are also what make this a semiarid climate versus an arid climate.

 

Temperature Trends

Below is a chart that describes both the average and record temperatures for Calgary, Alberta. Because of its high elevation there can be a large difference in the high and low temperatures on a given day, as the graph suggests.

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(Summarized from Canada’s National Climate Data and Information Achieves)

This second graph (below) depicts the average high and low in both January and July (the warmest and coldest months) over a 25 year period of 1985-2010. There is a trend line in each to show the overall average trends. In general Calgary appears to follow a consistent summer weather trend with a small increase in temperature of the years. However, their winters vary. 1995-1998 saw some of the colder winters, while recent winters have seen milder temperatures. The trend lines show that the average temperatures are decreasing contrasting to warmer temperatures they have been seeing. Again this graph also shows the large variability in high temperatures to low temperatures in a given month.

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(Summarized from the NCDC for the Calgary International Airport, http://www1.ncdc.noaa.gov/pub/orders/111825.pdf)

Calgary, Alberta vs. Dickinson North Dakota

Similarly to Calgary, Dickinson is a predominantly prairie and grassland region. However, while Dickinson sits at an elevation of 735 meters, Calgary sits at an elevation of 1,084 meters. Their temperatures are similar, although Dickinson does see warmer summers than Calgary in addition to being humid (unlike Calgary). Both climates experience Maritime Tropic, Continental Polar, and Continental Artic air masses. Maritime Tropic being associated with the summer months and Continental Polar and Continental Artic air masses associated with the winter months. The Continental Artic can bring sub-zero temperatures to both places. In addition, they both experience mid-latitude cyclones.

One of the biggest differences between the two places is that Dickinson does not have any mountains while Calgary has the Rocky Mountains. These mountains highly influence the temperatures in Calgary as well as provide them with the Chinook winds. Though both again have a similar geography the mountains and altitude are what sets these places a part.

(Tessa Bopp http://dickinsonndweather.blogspot.com/)

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Air Masses

Calgary is generally affected by maritime polar, continental polar, maritime tropical, and continental tropical air masses. However, only two of these will be found over the province at a given time. In the summer it is affected by maritime tropical (mT) and continental tropical (cT), while in the winter it is predominantly affected by continental polar (cP) and the occasional maritime polar (mP) air.

http://www.earthonlinemedia.com/ebooks/tpe_3e/temperature/temperature_air_masses.html

Mid Latitude Cyclones/Frontal Systems

Calgary’s precipitation occurs mainly from thunderstorm activity during the summer, but the mid latitude cyclone does produce a smaller amount of precipitation in the winters. Calgary experiences both cold and warm fronts but predominantly cold fronts.

http://www.climateandweather.net/world_weather/weather_fronts.htm

Chinook Winds

Chinook winds provide a warm relief of air during the cold long winters Calgary experiences. They have been known to raise the temperature as much as 30 degrees Celsius in a short amount of time. It can melt snow quickly and provide a welcome break from the cold. On average, Calgary may see about 30 days of Chinook winds a year. Chinook winds are caused by moist weather from the pacific coast, the cools as it climbs over the mountains and warms and it falls down the east side of the mountains. Usually they are started by sudden change in wind direction. As the winds climbs over the Rockies, rain and snows falls due to the release of moisture. Conditions on the west side are wet and moist, while on the east (Calgary) it is dry and cold. Chinook winds are most common in Alberta.

http://www.accuweather.com/en/weather-news/alberta-fires-fed-by-high-wind/59884

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 Calgary, Alberta Canada

Climate

Located in southern Alberta, Calgary sits in a transition zone between the Canadian Prairies and Canadian Rockies foothills. It is the largest city in the province of Alberta lies about 50 miles east of the Canadian Rockies.

Two major rivers, the Bow River and the Elbow River flow through the city; however besides the vegetation in the river valleys, the city holds a relatively dry climate. Summers in Calgary are short and warm, usually temperatures average in the 70’s. Winters are long and cold with temperatures averaging in the 20’s and 30’s. Due to the prairie type climate, Calgary has a lot of windy days, but it also has mostly sunny weather.

(http://www.tageo.com/index-e-ca-v-01-d-m794735.htm)

 

Daily High and Low Temperature/Precipitation

 http://weatherspark.com/averages/28211/Calgary-Alberta-Canada

Summers in Calgary are short and warm, usually temperatures average in the 70’s. Winters are long and cold with temperatures averaging in the 20’s and 30’s. The warmest month is generally July, while the coldest month is generally January. Due to their proximity to the Rocky Mountains, Chinook winds that are warm and dry blow throughout winter into the city allowing for a break from the cold. On average the snowiest month is January and the month with the most precipitation is June though it receives relatively little rainfall.

http://www.weather.com/weather/wxclimatology/monthly/graph/CAXX0054

Bowen Ratio

Calgary is a continental climate. There are not oceans near, but it is largely affected by the mountain region. The Bowen ratio describes net radiation heating and how it is portioned between sensible and latent heat fluxes. Because Calgary is a more arid region, with no oceans nearby and low precipitation, it has a higher ratio; North America averages at -.74.

http://en.wikipedia.org/wiki/Bowen_ratio