tailieunhanh - Delta's key the toefl test part 49

Tham khảo tài liệu 'delta's key the toefl test part 49', ngoại ngữ, toefl - ielts - toeic phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Review Test AAAAAAAAA Questions 30-40 If hurricanes are the largest storms on earth tornadoes are the most violent. Nothing produces more destructive power in a restricted area than a tornado as it passes by sweeping the ground clear of all movable objects. A tornado s devastating blasts of wind put all human life in jeopardy sending debris flying and lifting buildings from their 5 foundations. It is small wonder the sight of these intense storms strikes terror. In recent years the origin of tornado formation has been the subject of increasingly fruitful research. Nevertheless some mystery still surrounds tornadoes and their formation cannot be predicted with absolute accuracy even when conditions for their occurrence seem just right. Tornadoes are usually associated with thunderstorm 10 conditions. They require a moist airstream that is warm for the season and usually comes from a southerly direction. Tornadoes favor the warmest part of the day when solar heating and thunderstorm development are at their maximum. The funnel-shaped cloud of the tornado reaches down to the ground from a parent cloud that is part of an active thunderstorm. Several funnels may develop in a mature 15 tornado system with small vortices continually forming and dissipating while whirling around the central core of the main tornado. A tornado funnel can assume various forms from a thin writhing rope-like column of grayish white to a thick amorphous mass of menacing black. In the Northern Hemisphere tornadoes almost always spin counterclockwise. 20 87 percent of all tornadoes move from southwest to northeast. Rarely do tornadoes move toward the west. Tornadoes move forward at an average speed of 35 miles per hour but great variations have been recorded. During part of its course the great Tri-State Tornado of March 18 1925 moved at the astonishing rate of 73 miles per hour. 25 The great Tri State Tornado killed 695 people in Missouri Illinois and Indiana making it one of the most deadly .