STEM与日常科技·英语30篇（5）

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STEM轻科普：为何闪电击中高树却使其树干开裂（2026-D048）

Lightning seeks the fastest path to ground, so tall trees often become natural conductors during storms.
When current enters bark, moisture instantly vaporizes, expanding steam faster than wood fibers can stretch.
This explosive internal pressure splits trunks vertically, sometimes peeling bark off in long strips.
Sapwood conducts better than heartwood, so current follows moisture-rich layers beneath the bark.
Damage patterns reveal lightning’s path—even if no fire results, cells are permanently disrupted.
Trees with deep roots and high sap content suffer more severe splitting than shallow-rooted species.
Foresters use lightning scar mapping to assess forest resilience to increasing storm frequency.
High-speed cameras capture discharges entering crowns and exiting roots in under 100 microseconds.
Unlike metal rods, wood cannot safely channel gigavolt surges, making protection systems essential near structures.
Each scar tells a story of physics meeting biology in a fraction of a second.