|
| [View] (D) |
The sun shines over Canada every day of the year as it has for billions of years. Possible sunshine, the total number of hours of sunlight in the absence of obscuring clouds, mist, fog, dust, or terrain, depends on latitude. At the 49th parallel Canada could receive 4479 hours of sunlight annually; at 60N, the latitude along the top of the Prairies, 4536 hours, and at 80°N, 1000 km from the North Pole, 4567 hours. Cloud cover, especially in the late fall and winter, pollution, and shadows reduce the amount of sunshine actually received to about half these durations or less in most seasons.
The sunniest places are beneath the clear skies of the southern Prairies, where the average duration of bright sunshine exceeds 2400 hours a year. Only slightly less sunny is central British Columbia, the remaining Prairies, and southern Ontario. Despite the high rainfall, most of the Maritimes have about 1800 sunshine hours a year. The lowest figures are along the Pacific coast just south of the Alaskan Panhandle, where the range is from 1200 to 1400 hours a year, and over fog enshrouded parts of Newfoundland, where fewer than 1500 hours of bright sunshine occur in an average year.
Average annual Hours of Sunshine Across Canada
|
| [View] (D) |
In the summer, most of southern Canada receives over 250 sunshine hours a month, about 60% of the possible amount, for an average of 8¼ hours a day. Again, the duration of sunshine in the summer months is greatest over the southern Prairies (more than 340 hours per month), and the lowest figures are along the coast of northern British Columbia - a dismal 120 hours or 4 hours a day on average.
Cloudy weather and the lack of sunshine are common across the country in winter but are most pronounced along the northwest Pacific coast. Prince Rupert, for example, records clear skies only 15% of the time in December, with an average of 32 hours of sunshine.
The seasons north of the Arctic circle (67°N) are marked by periods of continuous winter darkness and summer light. At Cambridge Bay (69°N), there is continuous daylight from May 22 to near midnight on July 23, a period of 63 days. In winter, Cambridge Bay is in continuous darkness for 42 days, from shortly after noon on December 1 to January 13.
The Meteorologist's Crystal Ball
|
| [View] (D) |
Meteorologists really do use a crystal ball, or at least something that looks like one. This one, however, can't predict the future. It's the Campbell-Stokes recorder, and it's used for measuring periods of bright sunshine. The device is ingeniously simple. If you've ever used a magnifying glass to focus the sun's rays on a piece of paper and burn a hole it, you will understand how it works.
The instrument is located away from buildings to prevent shading. By means of a glass sphere, the sun's rays are focused on specially prepared cards, leaving a charred track for those portions of the day when the sun is shining brightly. The charts are changed daily and the charring is measured and recorded in tenths of hours.
Links to other sites on our star, the Sun.
The Green LaneTM,
Environment Canada's World Wide Web Site.