The findings, made by analysing 10 years' data of cloud heights from the north and south poles, open up a whole new perspective on our understanding of how clouds form and influence our weather and climate. Scientists have been aware of the daily global ebb and flow of electric current through the atmosphere for 100 years, when it was shown to vary consistently throughout the day wherever on the planet it was measured.
This regular variation, effectively a global electrical heartbeat, is known as the Carnegie curve, after the ship whose cruises provided the defining experiments in the 1920s. The electric current is caused by electrified storms across the world. Its daily peak occurs at 7pm GMT each day when the major sources of thunderstorms are the American and African landmasses. The current is usually weakest at 3am GMT, night-time across most of the world's continents, when there are fewest thunderstorms occurring globally.
Previously no connection had been made between this current and the formation of clouds. But, by analysing cloud base measurements made during polar darkness when there are few other influences on cloud formation, University of Reading meteorologists Professor Giles Harrison and Dr Maarten Ambaum found evidence for the first time that cloud heights are closely linked to the Carnegie curve.
Professor Harrison said: "What we found was remarkable. The variations from both north and south poles are almost identical, suggesting a strong link with the Carnegie curve, when other factors are taken out of the equation. This may arise from charging of small droplets in the cloud's base, encouraging them to stick together.
Read more at: http://phys.org/news/2013-03-revealed-earth-electrical-heartbeat-clouds.html#jCp