A World of Weather: Chapter 9 Introduction

CHAPTER 9

THUNDERSTORMS
At any given moment, over 1800 thunderstorms are in progress on Earth. Each thunderstorm is a boiling consequence of instability, a cumulonimbus cloud that can form, grow, mature and die within an hour (see Color Plate 13(l)). By definition, a thunderstorm is a convective rain or snow shower accompanied by lightning and thunder. Thunderstorms are a mixed blessing from Mother Nature: on the positive side, they provide a large amount of the precipitation needed for agricultural production and water resources over many parts of the world. In fact, in the Central Plains, the agricultural heartland of the United States, thunderstorms are the primary source of precipitation during the summer.

But thunderstorms can also be dangerous, accompanied not only by lightning but also by strong gusts of wind, hail, and even tornadoes, all of which can cause tremendous damage and even loss of life. In this chapter, we explore the variety, structure, life cycle, and human impacts of the thunderstorm. We begin this expose by explaining the traits that give thunderstorms their name - lightning and thunder.