8. Severe Squall Lines: Blue Electricity on the Leading Edge
Another dramatic context for blue lightning is found in squall lines, lengthy lines of intense thunderstorms. Often spanning hundreds of kilometres, these storm systems are well-known for their strong winds, lots of rain, and frequent lightning activity. Particularly prone to generate brilliant blue lightning is the leading edge of a squall line, where the cold outflow from the storms meets the warm, unstable air ahead of it. This happens because the front of the squall line’s air is often drier and clearer than that of the main body of storms. Strong updrafts and perfect circumstances for charge separation are produced when the squall line advances by the collision of air masses. For miles one can see the resultant lightning, blue against the dark storm clouds. Targeting squall lines not just for their ability to generate tornadoes but also for the amazing light displays they produce is common among storm chasers. A visual clue of the strength of the storm, the blue lightning in squall lines enables meteorologists to monitor the evolution of these strong storms.