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Lesson 10: Background
A squall line is composed of individual intense thunderstorm cells arranged in a line, or band. They occur along a boundary of unstable air, which gives them a linear appearance. Squall lines often have life spans of approximately 6 to 12 hours and extend across several states simultaneously. Strong environmental wind shear causes the updraft to be tilted and separated from the downdraft in squall-line thunderstorms. This prevents the precipitation from falling into the updraft and quenching it, as happens in the single-cell thunderstorm. |