18-QT1. Why do cities directly east of the Rockies (such as Denver, Colorado) receive more precipitation than cities east of the Sierra Nevada (such as Reno and Lovelock, Nevada)?
Circulation about the subtropical Bermuda high causes moisture-laden south winds from off the Gulf of Mexico to blow over terrain east of the Rockies while the circulation about the subtropical Pacific high causes dry northerly circulation over terrain east of the Sierras. This extremely dry region is blocked from Pacific moisture by the rain shadow of the Sierras and blocked from Gulf moisture by the rain shadow of the Rockies.
18-QT2. What climatic controls affect the climate in your area?
The climatic controls which are important here are (1) latitude, (2) land/sea distribution (we generally experience a continental type climate), (3) ocean currents (if the eastern Pacific were as warm as the Gulf Stream-heated west Atlantic we would almost certainly receive more precipitation than we do at present), (4) prevailing winds (if prevailing winds were from the east rather than the west, Utah would be even more arid from the rain shadow of the Rockies than it is from the rain shadow of the Sierras), (5) position of persistent highs (the position of the Pacific high in summer largely blocks incoming storms while its shifting southward in the winter subjects us to North Pacific storms moving along with the upper-level jet stream), (6) mountain barriers (the rain shadows of the Sierras and Cascades make Utah drier than it would otherwise be while orographic precipitation caused by lifting over the Wasatch Range makes the Wasatch Front much wetter than it would otherwise be), (7) altitude (altitude is a critical local factor; an entirely different climate can be visited by traveling just a few miles to the north, east or south because of the change that occurs in elevation).
18-QT3. Los Angeles, Seattle and Boston are all coastal cities, yet Boston has a continental climates rather than a marine climate. Explain why.
East coast cities such as Boston have a continental climate because prevailing westerly winds continually bring them under the influence of continental air masses while westerlies bring maritime air masses and therefore a maritime climate to west coast cities such as Los Angeles and Seattle.
18-QT4 Why are many structures in a polar regions built on pilings?.
Because of the repeated freezing and thawing of the permafrost near the surface it is necessary to support structures with pilings which extend down to depths such that natural thawing does not occur in the summer nor does artificial thawing caused by the heating of the building occur during the winter.
18-PE1. Suppose a city has the mean annual precipitation and temperature given in Table 18.3. Based on Köppen's climatic types, how would this climate be classified? On a map of North America, approximately where would this city be located? What type of vegetation would you expect to see there? Answer these same questions for the data in Table 18.4.
According to the data of Table 18.3 and the climatic classification criteria of Köppen the climate of the described city is Cfa. The city's classification is not marginal. It easily meets all the Cfa criteria. Hence it is deep in the southeastern part of the United States where the dominant vegetation is pine forests with some scattered oak trees.
The data of Table 18.4 describe a city with a classification of Dfb. The annual precipitation of 32 inches suggests it is in the eastern two-thirds of the Dfb strip which cuts across the northern United States and southern Canada, i.e., it is either in the extreme northeastern or Great Lakes portion of the United States or in the southeastern portion of Canada. Here the natural vegetation might include coniferous forests of pine, fir and\or spruce as well as oak and other deciduous trees.
18-PE2. Compare the following climate classifications for your area: (a) Ancient Greeks, (b) Köppen's system, (c) Thornthwaite's system. Which classification system is best for your area's mesoclimate? Macroclimate?
(a) Utah Valley has a temperate zone climate according to the system of the ancient Greeks. (b) The Köppen classification, according to the criteria on p.A-17, for Utah Valley would be BSk (dry, steppe, cool). (c) Thronwaite's classification for Utah Valley's climate would be steppe. The Köppen classification, with its greater detail would be best for dealing with the area's mesoclimate. The Greek classification would be best for characterizing macroclimate.