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More than 500 years ago, Leonardo DaVinci observed a phenomenon called hydraulic jumps. Today, a study from Stanford University scientists suggests that the physical mechanisms behind icy plumes, which serve as an early warning sign before a supercell storm occurs, are linked to this phenomenon.

The new study, titled "Hydraulic Jump Dynamics Above Supercell Thunderstorms," published in Science, discusses how and why a cloudy plume of ice and water vapor billows on top of a severe thunderstorm that could cause violent tornadoes, strong winds, and rain golf ball-size hailstones.

 Mechanism Behind Icy Plumes Preceding Supercell Storms Finally Explained
(Photo: Wikimedia Commons)
A supercell thunderstorm in Kansas. (Photo by Mike Coniglio/NOAA NSSL)

Supercells and the Formation of Icy Plumes

According to the National Weather Service, supercells are the least common type of thunderstorms and have a high chance of producing severe and damaging weather. It could cause tornadoes, strong winds, and large hailstones. More so, supercells consist of a deep and persistent rotating updraft known as a mesocyclone.

Supercell storms are most common in the central US but can also occur in other parts. They could either be the classic type or with high precipitation, low precipitation, or a miniature supercell.

Researchers explain in Stanford News that weaker thunderstorms could cause rising currents of moist air that flatten and spread out to reach the tropopause, the upper limit of Earth's troposphere, where an anvil-shaped cloud is formed.

The strong updraft of the supercell thrust the tropopause to the typically dry next layer of the atmosphere, creating an overshooting top that kicks streams of water vapor and ice that form the icy plumes or called an Above-Anvil Cirrus Plume (AACP) in the stratosphere.

Eventually, it speeds back to the troposphere, and air flows over the dome in the stratosphere, racing down the sheltered side. Researchers used a computer simulation of supercells and discovered that this excites a downslope windstorm at the tropopause, producing strong winds at 240 miles per hour.

Then dry air from the stratosphere and moist air from the troposphere joins in this fast jet, becoming unstable and mixing before exploding into turbulence. Study lead author Morgan O'Neill said that these speeds of storms have never been hypothesized and observed before.

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Icy Plumes Linked to Hydraulic Jumps

Researchers said that the new model suggests that the turbulence in the atmosphere that accompanies the icy plumes is linked to hydraulic jumps, a phenomenon similar to the mechanism behind waterfalls or when rushing winds tumble over mountains and produce turbulence on the downslope side.

This phenomenon was first observed in the 1500s by Leonardo DaVinci, but it was only until now that scientists have associated it with the icy plumes that serve as an early warning sign of supercell storms.

The study comes after a supercell storm occurred that left a trail of death and destruction across the northeastern part of the country. According to Science Alert, improved technologies could help scientists map the winds at the top of thunderstorms in high resolution to gather world data that can be used to improve meteorological models in the future.

More so, the study gave a broader picture of climate change as simulations show that hydraulic jumps push more volumes of water into the stratosphere, which will have a long-term impact on the climate.

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