Lightening strikes

This time-lapse photo, circa 1983, was shot from the bridge of the USS Trippe. The focus of the photo is the USS McCandless, in the distance, being struck with multiple bolts of lightning while we moved through the Caribbean Sea.

Contributed by John Lindsey

Does lightning strike the same place twice? You bet. I took a time-lapse photograph in 1983 while on the bridge of the USS Trippe.

The photo shows the USS McCandless ahead of us being struck by multiple bolts of lightning while we moved through the Caribbean Sea.

Severe turbulence — updrafts and downdrafts — found in thunderstorms produces friction between rapidly moving ice particles and rain traveling in opposite directions. This wipes off electrical charges, which produce an increase in pressure or voltage. The same effect can sometimes be experienced by rubbing your shoes across a wool carpet on a dry day and then touching a doorknob. The shock you feel is the electricity discharged to the doorknob.

When electrical pressure or voltage becomes high enough, charges between parts of the cloud or between the cloud and the ground are released as lightning. Lightning occurs at all levels in a thunderstorm. The majority of lightning strikes never hit the ground.

However, aircraft flying several miles from a thunderstorm can be struck by the proverbial “bolt out of the blue.” While in the Navy, our P-3 Orion — a maritime patrol aircraft — was hit by lightning over the Sea of Japan. The P-3’s outer skin is mostly made out of aluminum, and the electrical charge was passed through the aircraft’s skin and away from us. The metal skin was pitted with holes from where lightning had struck. When lightning does hit the ground, it starts with a relatively thin “leader” stroke from the cloud followed immediately by a heavy return stroke from the ground.

Amazingly, a lightning discharge is incredibly powerful — up to 30 million volts at 100,000 amps — but over a short duration. The sudden and rapid increase in heat causes the air around the lightning bolt to rapidly expand, then collapse, causing the shock waves that we call thunder.

Just one bolt is more than six times hotter than the surface of the sun.

Lightning takes the path of least resistance. It tends to hit the highest places. Never stand under a lone tree in an open field or on top of a mountain during thunderstorms.

If you’re backpacking in the mountains and you feel your hair standing on end, get as low to the ground as you can and try to take cover. On buildings, lightning rods allow electrons to stream off into the air or harmlessly to the ground. Wood structures and trees have high electrical resistance and can be heavily damaged unless grounded.

Lightning can also wreak havoc on electrical systems. At PG&E, the safety of our customers and crews in the field is top priority. So, if you see a downed power line — whether it was by a lightning storm or other cause, assume it is energized and keep yourself and others away.

John Lindsey is Pacific Gas and Electric Co.’s Diablo Canyon Power Plant marine meteorologist and a media relations representative.

Load comments