Forest Journal ~ When the Lightning Strikes

August 4, 2007

Forest Journal

When the Lightning Strikes
By Dave Anderson

Shimmering heat presses the landscape like a steam iron; the air is thick. An approaching cold front promises relief from days of oppressive humidity. A thunderstorm is brewing – you can almost feel it.

By late-afternoon, tall thunderheads billow like sails of Spanish galleons sailing east to the Atlantic. The dark armada of clouds descends from the west to make landfall in the hills of New Hampshire. Thunder booms in the distance. Songbirds grow quiet and the leaves rustle and flash pale bellies like fleeing trout as the sky grows black. With an audible rush of wind, the rain arrives.

Flash! A jagged bolt of lightning stabs Mount Uncanoonuc in the west. A searing crackle of white-hot lightning triggers an adrenaline surge of fear. The air is electric. The first fat raindrops spatter in the dry summer dust. It’s time to get inside… quickly now - run!

“One-thousand one, one-thousand two, one-thousand three…” I count seconds between each flash of lightning and the inevitable roll of thunder that follows. Each second is 1/5 of a mile to the place where the lightning struck.

“One thousand five…” Boom! The leading edge of the thunderstorm is a mile away. The approaching curtain of soft rain patters against the foliage audibly as the storm reaches the Merrimack River. Dark clouds run-aground, splintered hulls spilling swords of silver lightning and gold doubloons of rain as wind lashes the trees.

BOOM! A deeper rumble of thunder rattles walls and windows. Lightning spirals like a barber pole down a prominent white pine high on a hill and the tree explodes, splintering down its center when the sap boils beneath its bark. The top shears-off like a broken spar and falls to the deck. Farther down its trunk, pine bark is blown-off in a jagged line and scattered like shrapnel. The exposed sapwood glows yellow in the raw fissure. Even soil is thrown clear from the base of the trunk where the lightning reached the ground, ran along a root and dug a small furrow like an exclamation point. The pine is smoked, stricken in a flash.

After the storm, the air smells of burnt wire and wet asphalt. A siren wails in the distance and ragged shards of clouds race east trailing lighting and fading thunder. When the sky clears, a shaft of sunlight floodlights the arc of a rainbow across the valley. Birds resume chirping and mosquitoes emerge from damp woods where the cinnamon hint of autumn arrives on the cool evening air.

Fallen limbs lie shattered on lawns amid wind-torn leaves. The effects of a summer thunderstorm in New Hampshire is often limited to downed trees and power lines with relatively few homes damaged or people seriously injured compared to more severe thunderstorms which spawn spring tornadoes in the West. For the tallest trees on exposed hills or growing along the edge of fields, lakes and roads, severe summer thunderstorms are often fatal. People instinctively seek cover when lightning strikes. No such luck for trees - it’s not easy being green or one-hundred feet tall.

Mature white pines are usually the tallest trees in the forest. While they make excellent hunting perches for hawks and owls and are used by turkeys for night roosts, they are also natural lightning rods. You do not want to stand beneath one in a storm! Heat-killed trees create a special forest feature: electrocuted pines shed bark in huge plates, revealing cooked sapwood beneath. Seared pine pitch works like varnish to seal the heartwood against moisture and beetles that specialize in boring tunnels in rotting wood. Unlike pines which die, fall and rot on the damp forest floor, these dry, standing dead “snags” heat-killed by a fire or lightning strike may remain standing for more than a decade.

Even in death, lightning killed-trees live on. Lightning-killed snags furnish homes for new generations of wildlife. Insects eventually penetrate the veneer of cooked sap while woodpeckers chop larger holes in the trunk to reach them. Lightning-killed snags provide durable wooden homes for a variety of cavity-dwelling birds and smaller mammals. Cavities inside smooth, gray bark-free lightning snags are used by flycatchers, owls and woodpeckers for nesting and by bats as nursery colonies and day roosts. The squirrels, raccoons, porcupines and fishers use lightning killed snags as den sites.

Large dead trees are considered an integral element of a healthy forest ecosystem. In the woods, every ending is also a new beginning.

Naturalist Dave Anderson is Director of Education for the Society for the Protection of New Hampshire Forests. He can be reached through the Forest Society website at
Forest Journal appears in the Lifestyles section of the New Hampshire Sunday News and online at