Lightning #6 – Prevention
“30 – 30” rule:
When you see lightning, count the time from the flash until you hear the thunder.
Speed of light – 186,000 miles per second.
Speed of sound – 700mph = 1000’/sec, or it travels 1 mile in 5 seconds.
Each 5 seconds between flash and thunder is 1 mile away.
If the time is 30 seconds or less, seek safe shelter or do a lightning drill.
Wait 30 minutes until after the last thunder clap before leaving safety.
Imminent Danger – Hints that you are about to be struck by lightning:
Hair standing up or tingling skin.
Light metal objects vibrating or seeing a corona discharge.
Hearing a crackling or “kee-kee” sound.
On the water or in the water:
If possible, get off the water; the risk is lightning and the squall line.
Get at least 100 yards back from the water’s edge.
Do not seek shelter under trees or open-roofed shelters without walls.
Risk of a direct strike is greater in salt water than fresh water.
If you have to stay on the water, put on life jackets.
Prepare for the winds of the squall line and the potential to be capsized.
If in a boat, sit in the center and stay away from the mast and metal shroud lines.
For more detailed information about lightning and lightning-related injuries see the Wilderness Medicine Newsletter, Lightning – Beauty & the Beast, July/August 2003.
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