The Met Office confirmed that a ‘supercell thunderstorm’ has crossed parts of the UK bringing heavy rain, hail and lightning, with reports it had caused the ground to shake and lights to flicker. But what is a supercell thunderstorm?
Supercells are the least common type of thunderstorm but can wreak havoc, producing damaging winds, large hail and sometimes violent tornadoes.
They occur when a storm begins to rotate in a circle of about two to six miles wide, causing a strong vertical updraft in a phenomenon called a mesocyclone.
The mesocyclone pulls up warm, humid air from the ground and pushes down cool dry air, speaking force winds and sometimes creating golf-ball sized hail.
This cycle of warm and cold air makes the storm self-perpetuating meaning it can often last longer than typical thunderstorms.
Supercells occur when strong winds in the atmosphere cause stormy weather to start rolling, and then tip up the rolling storm, tilting it until it is spinning vertically.
Viewed from the ground, supercells take the shape of tall, anvil-shaped clouds, and tornados can often be seen emerging from the bottom.
Describing the process, a Met Office spokesman said: “Strong wind shear creates a horizontal spin in the atmosphere. The strong updraught tilts this rolling motion into the vertical, so that the spin occurs about a vertical axis, in the same sense as the rotation of a merry-go-round. Thunderstorms that exhibit persistent and deep rotation are called ‘supercells’.”
William Turner is a seasoned U.K. correspondent with a deep understanding of domestic affairs. With a passion for British politics and culture, he provides insightful analysis and comprehensive coverage of events within the United Kingdom.
