EVALUATE AND COMMUNICATE 9. Refer to FIGURE7 ; a cold front is approaching Brisbane. Describe how the weather will change when the cold front arrives.
10. Explain the interconnection between the Coriolis effect and wind. Answers and sample responses for this topic are available online.
LESSON 9.11 What are the causes and impacts of extreme weather?
LEARNING INTENTION By the end of this lesson you should be able to: • identify the causes of thunderstorms • describe the characteristics of thunderstorms
• define the causes of other types of extreme weather • explain the features of different extreme weather events.
Tune in Extreme weather can occur in a range of different
FIGURE1 What extreme weather events have you experienced personally?
environments and take an even greater range of forms. Recall a situation when you experienced an extreme weather event. Write a brief story about the event, including a description of the type of weather you saw and the impacts of the event.
9.11.1 What are the causes of thunderstorms? Thunderstorms, also known as electrical storms, form in unstable, moist atmospheres with strong updrafts, often near cold fronts. Approximately 1800 thunderstorms and 8 million lightning strikes occur daily worldwide. Darwin, Australia, has about 80 storms yearly, while Lake Maracaibo, Venezuela, averages nearly 300. Ancient Vikings thought thunder was Thor’s chariot and lightning marked the path of his hammer when he throw it at his enemies. Today, we know thunderstorms occur when cumulonimbus clouds generate static electricity (see FIGURE2 ). Lightning heats air to 20 000 ° C (more than three times hotter than the surface of the sun). Thunder is the sound caused by rapidly expanding air exploding. The time gap between lightning and thunder indicates distance (five seconds equals 1.6 km distance).
316 Jacaranda Humanities Alive 7 Victorian Curriculum Third Edition
Made with FlippingBook interactive PDF creator