Electrical discharges that happen when lightning strikes could be the key to how tornadoes form, according to Russian scientists.
They say images of tornadoes show evidence of nanoscale structures that produce a rapid charge of electricity, sending thunderclouds into a spin.
Researchers from the Russian Research Centre Kurchatov Institute in Moscow reported their findings on the physics website arXiv, which is owned and operated by the Cornell University in Ithaca, New York.
Tornadoes occur across the world, including the southern half of Australia.
They form a tunnel of wind that stretches from the top of cumulus or cumulonimbus storm clouds to the surface of the Earth.
Meteorologists say that winds caught up in the updrafts and downdrafts within these clouds are the starting point for tornadoes. In the updraft, winds that move parallel to each other in a shearing motion transform into vortex winds.
But some thunderclouds produce tornadoes while others don't, and the wind explanation doesn't account for that difference, the researchers say.
They suggest that electricity plays a bigger role than most weather researchers think, and at an extremely small scale.
The researchers analysed high-resolution x-ray and visual images of tornadoes from the U.S. National Oceanic and Atmospheric Administration photolibrary. In the images they saw structures usually seen at scales up to one billionth of a metre.
The researchers suggest that tornadoes are similar in appearance as you look at them using smaller and smaller scales. The same phenomenon is seen in fractals, mathematical patterns that look the same no matter how closely you look at them.
The researchers suggest that at smaller scales tornadoes are full of nanotubes of dust that allow for the rapid transport of electricity. The heat from the electrical charge is transformed into motion of the gas and plasma inside the cloud, producing a tornado.
But Australian tornado researcher Andrew Watson, regional director of the Bureau of Meteorology in South Australia, said that the research was "clutching at straws".
Watson said he doubted that the scale of the processes leading to tornado formation was so small, and that he believed tornadoes were formed by processes operating over a few kilometres.
"Air into the updraft [of a cumulus cloud] is drawn from a few kilometres around. Although the tornado itself is smaller than this, maybe a few hundred metres, it is still bigger than this nanotubular dust," Watson told ABC Science Online.
"I don't believe dust plays a role in the development of a tornado."
Watson questioned the use of still images to study the origin of tornadoes, as dust and debris picked up by the tornado could change its appearance dramatically.
"It is dangerous to make a conclusion from a small collection of photos. Taking snapshots and analysing them is pretty tenuous."
In Australia there up to 30 tornadoes are observed every year, some only lasting for a few minutes, he said.
"There might be more, but unlike the U.S., most of inland
Australia isn't populated so we don't see them."