Climate

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Climate sculpts the landscape through heat, cold, humidity, light and wind. In Canada, the variety of landscapes shows the diversity of our climate. In the north, low precipitation and cold temperatures favour permafrost and suppress vegetation growth, resulting in treeless tundra. South of the tundra, on the Canadian Shield, summers are short and warm, and winters are long and cold. Annual precipitation is abundant, allowing coniferous forests to establish and grow. On the Pacific coast, the combination of heavy rainfall and mild temperatures year round supports temperate rain forests. On the Prairies, the large number of days of sunshine affects the development of the agricultural landscape. In the Maritimes, the Atlantic Ocean moderates the climate such that winters are generally long and mild, and summers are short and cool. These conditions help in the development of forests. Finally, around the Great Lakes and alongside the St. Lawrence River as far downstream as the city of Québec, the climate is characterized by relatively warm summers and cool winters, moderated by surrounding water bodies. These conditions are suitable to the development of mixed wood and broadleaf forests.

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Factors that Control Climate

Climate has a variety of components, such as temperature, precipitation, wind speed and direction, humidity, sunshine, type of clouds, cloudiness, evaporation, lightning, visibility and atmospheric pressure. Each of these components results from the interactions of several of the following factors:

• The shape of the Earth and its motion around the Sun determine the quantity of sunlight and heat that every place on the Earth's surface receives.
• The atmosphere works as an insulator and evenly redistributes the heat received from the Sun.
• Large water bodies, such as the Great Lakes and the oceans, store up heat and exchange it with the surrounding air. Because water heats up more slowly than land and holds the heat longer, large water bodies have a moderating effect on climate. They also are the source of the moisture that causes precipitation.
• Relief, such as high mountains, plains, lowlands and highlands, modifies greatly the regional and local climate because of such features as elevation, slope, orientation and exposure.
• Vegetation cover affects humidity, temperature, amount of sunshine, wind speed and precipitation. For example, in a dense forest, humidity will be higher and wind speed and precipitation lower than in a field or a clearing, where the vegetation cover is less dense.
• The shape and type of surface material also have an effect on the climate. For example, large and tall buildings of downtown areas and large surfaces of cement and asphalt produce climatic differences compared to neighbouring rural areas, where there are few buildings and the ground is mainly covered by vegetation. Sources of heat, humidity and atmospheric pollution, found in urban areas but generally not in rural areas, can also affect local climates.
• Ocean currents move heat and cold from one place to another. For example, the Gulf Stream in the Atlantic Ocean redistributes heat from the tropics toward northern Europe. Unfortunately, because of this current's trajectory, eastern Canada does not benefit from this warming effect. On the Atlantic coast of Canada, however, extensive banks of fog develop when the cold and ice-filled water from the Arctic, travelling within the Labrador Current, meets with the warmer water of the Gulf Stream.

The Importance of Climate in Canadian Life

Climate plays a major role in several sectors of the Canadian economy. Every winter, snow removal uses up a major part of almost every city's budget. Agriculture depends on temperature and the right amount of humidity and precipitation to produce abundant crops. The tourism industry depends on snow for ski resorts and winter festivals. Climate also has an influence on the building industry: low winter temperatures necessitate buildings with insulated walls and windows. Finally, because of the climate, Canadians are among the world's largest users of energy.

The subjects discussed in this theme are the two most observed elements: temperature and precipitation (coming in 2006). A third subtheme presents aspects of snow cover.