Every time arctic air drops south, and temperatures plummet well below zero, social media lights up with a scary (and slightly cinematic) rumor called "exploding trees."

As temperatures drop in Iowa this weekend, curiosity and concern about trees exploding from the cold have grown. Here's what really happens.

It is indeed possible for trees to split apart in extreme conditions and to do so quite noisily, she said, typically when there’s a big swing in temperatures. In these instances, sap rapidly freezes when the mercury plummets and the tree expands, its trunk or limbs busting open like the buttons on a too-tight shirt after Thanksgiving dinner.

A tree-mendous freeze. Forecasters are warning that expected subzero temperatures could cause trees to explode as a brutal cold snap is expected to wallop most of the country in the coming days. Trees may split and burst across the Midwest and Northern Plains Friday and Saturday as a bitter Arctic blast from Canada sends temperatures plunging to roughly 20 degrees below zero,