Figure 5.6

GEO-GRAPHIC: Anatomy of a squall line. (A) This image shows a cross-section of a multicell thunderstorm organized along a squall line. The inset figure shows the squall line in a top view. The movement of the system is from left to right. As the system moves forward, warm air rising over the gust front gives rise to new cells (labeled Cell A and Cell B). Over the course of about 30 minutes, these cells will grow and replace cell C. A derecho originating from the downdrafts can be as damaging as hurricane or tornado winds. (B) This squall line moved over Washington, D.C., on July 25, 2010. It did significant damage to trees and power lines, causing extensive power outages.

(B. NOAA-NASA GOES Project)