Page 140 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

104
part I The Energy–atmosphere System
150
1400
298
Whitehorse
1400
165°
150° 18001800 1400
1600 1200
1400
1400
1600
1800 2000
245
Prince Rupert
288
Vancouver
2000 1800 1800 2000
279
Churchill
312
Winnipeg
1400
0
120°
250
500 KILOMETRES
1600 1800
Ave3r0age Annual Hours of Sunshine
1200 1600 2000
45 Number of days
with some sunshine
1200 1000 1200
1800 1600
179
Resolute
15°
30°
1400 268 45° St. John’s
Sunniest Places in Canada
1800 1800 2000
284
2000
1600
270
Sunniest month
Greatest average annual number of sunny hours Major city with greatest annual average number of sunny hours
Sunniest small town under 10 000 population Sunniest provincial capital
Sunniest year on record
Shortest spell of consecutive days without sun Sunniest summer on average
Sunniest winter on average
Greatest annual number of hours of possible sunshine
Greatest annual average number of sunny days
Greatest number of sunny days in one year Greatest number of sunshine recorder sites
May 1973
1976
June, July, August December, January, February
1976
1800
320
Regina
1400
1800
322
Edmonton
2400
Quebec City
Charlottetown
1600
290
105°
ARCTIC OCEAN
1600
1600 1800 2000
1600
2400
Eureka, NT Estevan, SK
Saskatoon, SK Coronation, AB Regina, SK Manyberries, AB Charlottetown, PEI Yellowknife, NT Gimli, MB
Alert, NT
Calgary, AB Medicine Hat, AB Québec City, QC
2000
90°
621 hours 2537 hours
2450 hours 2490 hours 2331 hours 2785 hours
10 days 1065 hours 376 hours
4580 hours 329 days
346 days 84 days
309
Ottawa
288
Saint John
1800
▲Figure 4.12 The variation in patterns of bright sunshine across Canada. The greatest amounts of bright sunshine are received on the prairies even though these areas are farther north than southern Ontario and Quebec. What factors influence this pattern of sunshine?
[The Climates of Canada, David Phillips, Senior Climatologist. © Environment Canada, 1990. Used by permission.]
Northern Hemisphere, January is usually the coldest month, occurring after the December solstice and the shortest days. Similarly, the warmest months of July and August occur after the June solstice and the longest days. Figure 4.12 shows the variation in patterns of bright sun- shine across Canada.
A Simplified Surface Energy Budget
Energy and moisture are continually exchanged with the lower atmosphere at Earth’s surface—this is the bound- ary layer (also known as the atmospheric, or planetary, boundary layer). The energy balance in the boundary layer is affected by the specific characteristics of Earth’s
surface, such as the presence or absence of vegetation and local topography. The height of the boundary layer is not constant over time or space.
Microclimatology is the science of physical condi- tions, including radiation, heat, and moisture, in the boundary layer at or near Earth’s surface. Microclimates are local climate conditions over a relatively small area, such as in a park, or on a particular slope, or in your backyard. Thus, our discussion now focuses on small- scale (the lowest few metres of the atmosphere) rather than large-scale (the troposphere) energy-budget compo- nents. (See Chapters 10 and 11 for further discussion of climates and climate change.)
°
60°
2000
294
London
2000 1800
75°
Halifax
1800
ATLANTIC OCEAN
60°
249
Iqaluit
265
Goose Bay
45°
45°