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Tornadoes: Extreme Weather Events

Tornadoes: Extreme Weather Events. Chapter 8. Tornadoes in North America. A tornado is an extremely violent windstorm It descends from the clouds for a few minutes to cause major destruction Springtime is tornado season in the American interior. Tornadoes in Canada.

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Tornadoes: Extreme Weather Events

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  1. Tornadoes: Extreme Weather Events Chapter 8

  2. Tornadoes in North America • A tornado is an extremely violent windstorm • It descends from the clouds for a few minutes to cause major destruction • Springtime is tornado season in the American interior

  3. Tornadoes in Canada • Most tornadoes occur in the United States • An average of 655 tornadoes every year • Canada’s leading twister province, Ontario can expect only about 25 tornadoes a year • In both Canada and the United States, amateur storm trackers often exchange information about tornadoes using the iternet

  4. Tornado Research: What we know • Tornadoes are rare events that are very difficult to track and predict • Tornadoes: • touch down and lift off suddenly • Sharply change direction • Destroy a house and leave the next house untouched • Winds of an F5 can twist heavy metal around a tree

  5. Characteristics of Tornadoes • Prime time between mid-March and June • Usually strike between 3:00 – 6:00 pm • Fast rising currents of warm humid air star the process • Columns of cooler air rush down towards the ground to replace these rising currents • Descends from the sky

  6. Characteristics of Tornadoes • Form a funnel of air known as the vertex • Winds can surpass 500 km/h • Travels across the ground at about 60 km/h • Winds inside the funnel rotate counter clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere

  7. The Strengths of Tornadoes • Winds of a tornado are a major source of power and cause destruction in three ways • Winds rotating around the vortex are powerful enough to blow down trees, tear off roofs and flatten buildings • Pressure difference can cause building to implode (to cave in) due to the low pressure inside the funnel • Air swirls upwards around the vortex and can lift very heavy objects • Strength of tornadoes is measured on the Fujita-Pearson scale.

  8. Early Tornado Detection Saves Lives • Technologies such as Doppler radar, aerial photography, and satellite imaging are used to track and report dangerous weather conditions • During a weather watch, a red band appears across the bottom of the television screen. It identifies the locations affected • If conditions worsen, a weather warning is issued, at which time the whole screen is coloured or flashes, and people in specific areas are advised to seek shelter

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