Lightning

Ryan Skinner leans on a tree in his yard that was hit by lightning last summer. This month, he said, a strike sounding even more menacing rocked his Pine Tree subdivision neighborhood located in Harmony. Both incidents serve as reminders of Wisconsin’s severe weather season (April through September).

Ryan Skinner, Town of Harmony, contacted the Milton Courier after what he described as a “superbolt,” shook his home, and, by his account, those of his neighbors living on a cul-de-sac in the Pine Tree subdivision. It happened, he said, on June 5 at approximately 3:30 a.m.

May, June and July are the most active in Wisconsin’s April through September tornado and severe weather season, according to the Wisconsin Department of Health Services.

Last summer, Skinner said, a tree in his backyard was hit by lightning, but the June 5 event was stronger and louder than anything he’d ever heard. The experience sent him to social media, looking for others who might have heard or felt the sound. Several responded on Facebook saying they had.

Several days later, cul-de-sac resident Todd Buggs told the Milton Courier he, too, heard the sound, describing it as a “loud crack.” There had been some hail earlier that evening, he said, typical of storms moving through the area.

Neighbor Eileen Kintner said she and her 4-year-old beagle, “Buddy,” were also awakened by the sound, describing it as “a giant explosion; it shook the house,” she said.

National Weather Service data

Marcia Cronce, a meteorologist with the National Weather Service in Sullivan, shared with the Milton Courier data maps of “cloud flashes and (cloud-to-ground) strikes” in the area around 11:45 p.m. June 4 and midnight June 5, times when the weather service takes regular data samples, she said. She confirmed storms in the area during the early morning hours of June 5, noting that, in her opinion, the activity was not out of the ordinary for this time of year.

A data capture from midnight June 5 showed that out of the 235 cloud flashes over the area, 28 produced strikes with negative charges and one produced a strike with a positive charge.

In her experience viewing such data, Cronce said, the number of flashes and strikes were “normal,” noting that most strikes within area storms have a negative charge. Strikes with positive charges are more dangerous and not as common.

“I usually see at least one in thunderstorms,” she said, adding she had no way of knowing how the early morning June 5 strike might have been charged.

How is lightning formed?

Said Cronce: “There are various charges in the atmosphere. In a thunderstorm, cloud charges end up separating so you get positive and negative (charges) up in the cloud and then it channels down or is attracted to positive or negative (charges) at the ground. Once the opposite charges build up, it creates a connection and you get multiple strikes of lightning within one channel of the charge. That’s why it looks like lightning flickers.”

Janesville resident Tom Purdy, who documents area weather phenomenon in a freelance capacity, said, he, too, had a friend, living on the northeast side of Janesville, who was awakened by the June 5 event.

“He thought it was a low meteor,” Purdy said.

“Anytime you get thunderstorms it is possible to have large lightning strikes. Rain can amplify the effect, too,” Purdy said.

More about lightning

Assistant State Climatologist Ed Hopkins, with an office at UW-Madison, has been involved with weather as a climatologist and university professor for over 40 years.

Lightning comes in three types, he said: within a cloud, when charges separate into positive and negative ions, making a discharge between them. Lightning discharge within a cloud is the most frequent type of lightning.

A second type applies the same science but occurs between two clouds.

A third type is cloud-to-ground lightning, which is the kind that can be deadly to people.

“This occurs when you have a lower part of a cloud with negative charges and then there is a buildup of electrostatic charges, and then the ground below becomes positively charged, and there is a discharge between the two.

“Cloud-to-ground lightning is usually described as negative because the charge within the cloud is negatively charged,” Hopkins said.

Charges in clouds can be hard to identify, and some clouds have a positive orientation, he said, adding that, until about 30 years ago, climatologists mostly identified clouds with negative charges as the “step leader” or pathway that produced cloud-to-ground lightning.

“People used to think negative charges did the whole trick,” he said. Today climatologists recognize that there are occasions where there are positive discharges originating in the cloud, he added.

“People also say there are cases where, at the beginning of the storm, the clouds are negatively charged and sometimes by the end they see positive discharges and they don’t know why,” he said.

Some see the change as an indicator of developing tornados, but there is more research to be done, he said.

Describing the intensity, which can sometimes occur with strong summer storms along the Wisconsin and Illinois border, he said: “Lightning is an electric discharge and it heats a thin column of air (that has) the thickness of a pencil. That column is heated on that lightning channel because of the recombining of positive and negative ions. When charges recombine, energy, in the form of heat, is given off so rapidly that it can cause a sonic boom.”

Columns of air can heat to 50,000 degrees within a fraction of a second, he said.

That kind of discharge can shake walls and cause damage, he added.

While those who track weather have different points of data collection available, “more often than not, you still need people on the ground to tell you what’s happening,” Hopkins said.

“Ground truth,” he said comes from observers in the field who collect data that can be compared with information collected through radar and other tracking networks.

For more information about weather, visit Wisconsin State Climatology Office: http://www.aos.wisc.edu/%7Esco/clim-history/index.html.

For information about staying safe during severe storms, visit: https://www.dhs.wisconsin.gov/climate/tornado.htm.

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