A Tale of Three Chimneys

Tropical landmasses in the Americas, Africa, and Asia produce more lightning than anywhere else. Of these, Africa is the clear leader in lightghtning production on a continental scale. However, thunderstorms in the Americas generate the most Wilson current. We use the TRMM satellite to understand why.

Tropical Rainfall Measuring Mission (TRMM) satellite observations are used to estimate the amount of current each tropical electrified cloud provides to the Global Electric Circuit. Collecting these estimates more than a decade makes it possible to quantify the importance of various cloud types and the distinct “chimney” regions for the global circuit.

The majority of the global generator current is supplied by thunderstorms (61%), while electrified shower clouds that do not produce lightning provide the remaining current (39%). Most of this current comes from large mesoscale storms that have electric fields at 20‐km altitude greater than 1 kVm−1 and individual current contributions exceeding 1 A.

Of the three tropical chimney regions—the Americas, Africa, and Asia—Africa produced the most lightning, but the least current. This is because there are few electrified shower clouds in Africa compared to the Americas and Asia, and Africa thunderstorms appear to generate weaker electric fields and Wilson currents than their American and Asian counterparts.