Storms Wednesday and Thursday usher in spring

Friday, March 23, 2007 2:36 AM CDT

Wednesday's storms usher in spring

By Paul Sloth

Journal Times

MOUNT PLEASANT - James and Hope Krenzke had no idea what happened when a loud bang woke them early Thursday morning.

Lightning split a pine tree in half right next to their home on Clinton Lane, they later learned, when a neighbor called.

"It kind of exploded. It was a helluva bang. It spread out all over the place," James Krenzke said of his tree. "We hit the ceiling when it went off."

The Krenzkes spent the day finding splinters from the roughly 50-foot tree they planted when they built their house in 1964.

The Krenzkes tree was a casualty of the thunderstorms that rolled through southeastern Wisconsin Wednesday night.

However, the rain helped wash off Racine County's winter coat.

While the first day of spring - when the sun crosses the equator, creating equal amounts of night and day - usually makes it onto calendars in the United States, it often slips past with little fanfare.

In Japan, people celebrate the vernal equinox. Shunbun no Hi is a national holiday there.

Unless you have time to watch grass grow, you could be fooled into thinking things around southeastern Wisconsin changed overnight, especially after Wednesday's storms.

It might seem like things turned green instantly, too.

"A lot of it is perception. It's not just an overnight, spectacular thing, like it may seem," said Patti Nagai, a horticulture educator with the Racine County UW Extension. "It's a gradual process. But it is greener."

Nagai said a combination of factors contributes to the gradual greening of things. Air temperatures are rising. The ground is thawing. Not to mention, "We've had lots and lots of water," Nagai said.

"But lighting does influence things. Lightning adds nitrogen," Nagai said.

The atmosphere is mostly nitrogen, Nagai said. However, plants can only use nitrogen in particularly form. One of the things lightning does is change that form.

When lightning bolts discharge, they ionize the air and produce a nitrogen oxide called nitrate. According to recent studies, this process could generate more than 50 percent of the usable nitrogen in the atmosphere and soil. Nitrogen is an essential plant fertilizer.

Rainfall can supply nitrogen to the soil. The heat generated by lighting causes nitrogen and oxygen gases to combine as nitrate, which is then washed out of the air.

Nitrate is a form of nitrogen, which plants can absorb. This source provides about seven to 10 pounds of nitrogen per acre enter the soil annually.

Karen Delahaut, a phenology specialist at the University of Wisconsin-Madison, said while the lightning plays only a minor role, Wednesday's rains would precipitate the greening and growth of a lot of different plants.

The science of phenology, an area of science that studies the timing of natural events, in animals and plants, over a period of years, dates back to 974 B.C. Conservationist Aldo Leopold was one of Wisconsin's first phenologists.

With warmer temperatures and brighter skies, people are looking closely now for signs of spring. While most people talk about the first Robin, Delahaut said it's a bit of a misnomer, because a few will spend winter in Wisconsin.

Along with the greening grass, tulip and daffodil bulbs are starting to emerge. Earthworms are, too.

For many, noticing how green the grass really is can be a bit of an epiphany. Nagai said soon there would be another epiphany, "Hey, the trees are blooming," and people with allergies will notice it, too, once their noses start to run.

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