Thunderstorm on EARTH Magazine

Blogging on EARTH: First dispatches from EGU

Thu, 05 Jan 2012 06:41:58 -0500

EARTH’s Carolyn Gramling is taking in the European Geophysical Union meeting this week in Vienna, Austria. Here are some of the sessions that have caught her interest so far.

How many thunderstorms are there around the world at any point in time?

About a century ago, scientists thought that number was about 2,000, based on an estimated number of lightning flashes per second (back then, thought to be about 100). Nowadays, of course, we have much better estimates of lightning flashes — satellite observations suggest there are actually only 45 flashes per second.

Cityscape, 'wet regions' fueled Atlanta tornado

Thu, 05 Jan 2012 06:41:58 -0500

On March 14, 2008, at 9:38 p.m., something happened in Atlanta that had never happened in the city’s 171-year history: A tornado ripped through a 10-kilometer-long swath of the city’s downtown. The twister, with winds reaching 210 kilometers per hour, blew out skyscraper windows and stalled a major college basketball conference tournament.

Larger raindrops may make tornadoes more likely

Thu, 05 Jan 2012 06:41:58 -0500

A tornado such as this one is more likely to form if the storm produces larger precipitation, such as raindrops or hailstones. NOAA

The most violent tornados stem from massive supercell thunderstorms, such as this one. NOAA

A huge thunderstorm was gathering above central Oklahoma on May 20, 1977. As the storm intensified, a tornado began to form and struck the ground, leaving wreckage in its path. Although the tornado itself is now well-known, the forces behind its formation are still surprisingly sketchy. Using high-resolution modeling, however, a new study reveals how some atmospheric conditions can make tornadoes more — or less — likely to form.

Storms brewing over volcanoes

Thu, 05 Jan 2012 06:41:58 -0500

Lightning illuminates the night sky over Redoubt Volcano in March 2009. Photo courtesy of geologist and photographer Bretwood Higman

Two hundred years ago, a sea captain was sailing in the Azores, a Portuguese archipelago in the middle of the Atlantic Ocean, when he observed “an immense body of smoke rising from the sea.” As he watched, the smoke, from a volcanic vent offshore of the island of St. Michael’s, began to rotate on the water “like a horizontal wheel,” the captain wrote in his 1811 account of the event. The rotating smoke and ash grew into a dark column and ascended high into the sky, spawning waterspouts and flashes of lightning. “To give you an adequate idea of the scene by description is far beyond my powers,” he wrote.