The sheer size of western Canada makes for different climates and radically varying temperatures, which rise or fall with changes in elevation, latitude, slope aspect, and distance from the ocean. The coastline of British Columbia boasts the mildest climate of all Canada, but this comes with one drawback—it rains a lot. The two main cities, Vancouver and Victoria, lie within this zone.
As prevailing moisture-laden westerlies blow across British Columbia, the cold heights of interior mountain ranges wring them dry, producing drier, hotter summer temperatures and sunnier skies the farther east you travel. The same is true in winter, except the temperature range is reversed—winter temperatures in Calgary are lower than in the interior of British Columbia and significantly lower than in Vancouver.
In winter, the dry winds blasting down the eastern slopes of the Canadian Rockies can raise temperatures on the prairies by up to 40°C (72°F) in 24 hours. Called chinooks, these desiccating air currents are a phenomenon unique to Alberta.
Seeing the aurora borealis, or northern lights, is an emotional experience for some, spiritual for others, and without exception is unforgettable — an exhibition of color that dances across the sky like a kaleidoscope.
Auroral light is created through a complex process — a spontaneous phenomenon with no pattern and no “season” — that starts with the sun and finishes within the Earth’s atmosphere. Essentially a huge atomic-fusion reactor, the sun emits the heat and light that keep us alive, and also emits ions that are thrust through space at high speeds. When these electrically charged particles reach the Earth’s rarefied upper atmosphere — about 180 kilometers (112 miles) above the surface — they are captured by the Earth’s magnetic field and accelerated toward the poles.
Along the way they collide with the atoms and molecules of the gases in the atmosphere, which in turn become temporarily charged, or ionized. This absorbed energy is then released by the ionized gases, often in the form of light. The color of the light varies depending on the gas: Nitrogen atoms produce a violet and sometimes red color, oxygen produces green or, at higher altitudes, orange.
Because the magnetic field is more intense near the north and south magnetic poles, the lights are best seen at high latitudes. In northern latitudes the light show takes place up to 160 nights annually, with the best displays north of the 60th parallel. They generally start as a faint glow on the northeastern horizon after the sun has set, improving as the sky becomes darker.
In general, the human species live in the middle latitudes and is accustomed to the particular set of natural phenomena common to those latitudes—the sun rises in the east each morning and sets in the west each evening; night follows day; vegetation is lush; and water most often occurs as a liquid.
But in the Far North, these comfortable patterns don’t exist. In winter, the sun doesn’t rise for days (or, in the high arctic, even months), whereas in summer, it circles endlessly around the horizon. And for more than half the year, lakes, rivers, and the ocean aren’t free-flowing water but solid ice. The region’s climate is harsh, but the image of the Canadian North being a land of eternal ice and snow is a misconception. During the summer months, late May–September, the weather can be quite pleasant.
Much of the north is covered by permafrost—ground with an average annual temperature below freezing. In much of the mainland, the topsoil melts each summer. This is known as an active layer of permafrost. But farther north and in the Arctic Archipelago, the ground remains continuously frozen in a layer 2–500 meters (6–1,640 feet) deep, which is called continuous permafrost.
© Andrew Hempstead, from Moon Western Canada, 3rd Edition