LANSING, Mich. (WLNS) — It has been a stormy start to the summer here in Mid-Michigan. What causes thunderstorms to form in the first place?

The rumble of thunderstorms across the country this week is a noisy reminder that summer is arriving—and with it, the mix of heat, humidity and unstable air that fuels these bursts of wild weather.

A week ago, Milwaukee and much of Wisconsin was slammed by severe weather – and more often than not, the storms rolled through late in the day or overnight. That isn't unusual, though, because ...