Mackenzie Gas Pipeline and the Boreal Environment Information Project

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Climate Home Climate Patterns River and Soils  Mackenzie River Cities Climate Change Links and References

Before proceeding further into the website, I invite you to read the following definitions to better grasp the ideas that are referred to throughout  the material.

Definitions

Weather refers to daily meteorological condition contributing to temperature trends and precipitation in the atmosphere. Meteorology is the science that embodies the knowledge of the atmospheric processes. Weather is the state of the atmosphere at any given time and place with regard to temperature, air pressure, humidity, wind, cloudiness, and precipitation. Scientists use weather to explain for conditions over short periods of time.


Climate refers to the average monthly temperature and precipitation over several decades, which includes all components of the atmosphere, ocean, sea-ice, vegetation, rivers, and human influences. The term climatology describes the pursuit of knowledge for the average weather (usually taken over a 30-year time period) for a particular region and time period, including the variability and extremes of weather. Climate is not the same as weather, but rather, it is the average pattern of weather for a particular region. Weather describes the short-term state of the atmosphere. Climatic elements include precipitation, temperature, humidity, sunshine, wind velocity, phenomena such as fog, frost, and hailstorms, and other measures of the weather. (Green Lane, 2003)

Climate Regions describe areas that result due to having similar long-term weather characteristics. The geographic patterns of both soils and vegetation are intimately linked to climate.

The Climate System refers to the conceptual statistical construction of all elements that are in relation to each other to form long term weather patterns.
Please view the following illustration to observe the different components that involve the creation of our climate system.

General Circulation

The weather and circulation of the atmosphere are essentially the result of a balance of energy.  Energy enters the earth from the sun in the form of radiation, termed as insolation. The radiation in the form of heat energy drives the primary motion of circulation of the atmosphere and the ocean.

At the equator, where insolation is the most intense, air rises producing low pressure. The air cools and diverges aloft, moving toward the subtropics where it descends, producing high-pressure and diverging at the base, sending air toward both the equator and higher latitudes. These movements of air generate the Trade Winds and the Westerlies. The dense cold air at the poles spills out of the Arctic and Antarctic, flowing in an easterly direction, coming in contact with the warmer air of the Westerlies at the Polar Front. The polar air is cold and dense causing the Westerlies to rise and flow over the arctic and antarctic, forming a low-pressure area. (Christopherson, 2002)

The following websites provided by Environment Canada present more detail about the existing climate. Please view.
Natural Factors Effecting Climate                     The Greenhouse Effect                            Human Factors

Atmospheric circulation is classified into three forms:
primary circulation – general worldwide circulation
secondary circulation - migratory high-pressure and low-pressure systems
tertiary circulation - includes local winds and temporal weather patterns

The global circulation of the atmosphere can best be illustrated with the following illustration. Note that the circulation that occurs over the equator and the circulation over the poles. Canada's weather and climate is influenced from the areas of relatively low pressure formed by the westerlies that move over the arctic.

Circulation that influences the Northwest Territories

The physical surface climate of the Canada is driven by global climate and and in turn, helps drives global climate.
Canada is located in the northern hemisphere. The Northwest Territories receive low insolation.
According to the figure, The region of the Northwest Territories are represented within the area between Barrow, Alaska, and Quebec. The Territories only receive their largest amount of insolation during the summer months.  The Northwest Territories lie within the northern hemisphere's westerly wind flow. These wind flows cover the territories of Canada at all times of the year. The westerlies dominate the dynamics of the N.W.T.'s and Canada's climate. The physiography of the N.W.T.'s influences the tertiary circulation which determines the surface climate.
The Western Cordilla, the complex of mountains, plateaus, and valleys that run through the N.W.T. and into western Alberta, play a big role in the weather patterns that occur over the Mackenzie River Basin. Due to the mountains, most of the convection that influences the weather over the river basin is influenced from the arctic. The physical geography allows for arctic air to funnel into the Mackenzie River valley throughout most of the year. Also, the oceans help with the climate characteristics. The oceans to the west remain unfrozen all year and the arctic oceans bring ice to and away from shore.
The main point here is that most of the weather and climate of the region is largely influenced by the westerlies.

Large scale disturbances occur as a result from the westerlies that eventually lead to the development of the cyclones and anti-cyclones that create events such as the Alberta Lows that travel from the arctic above the N.W.T.'s into the United States.
The system of cyclones and anti-cyclones that develop merge to form troughs and ridges.

The following illustration at right displays the controlling feature of the westerlies that influences the far reaching relatively warm temperatures experienced in the Mackenzie River Basin during the winter, and the temperate temperatures during the summer.
Generally,a ridge of high pressure axis lies over Western Cordilla (summer) or East Pacific (winter).  When an assertive ridge appears (known as a blocking high) unseasonable winter thaws or cool summer weather occurs in the N.W.T. and the Mackenzie River Valley. (Baily et al, 1997)