Lightning - The Facts, Its Danger, and Your Safety

The gentle rumble of thunder tends to provide a feeling of serenity, and it is easy to incautiously admire one of nature's most impressive spectacles - lightning. However, because of its commonplace in everyday life, we often neglect to appreciate the real danger it presents. I'm as guilty of this as anyone else, but I wanted to take a minute to remind everyone that lightning is serious business and is nothing to take haphazardly, especially on the golf course.

We were reminded of this yesterday when a lightning bolt hit a large maple on the right of 2 fairway. There was no rain associated with this strike, and the sky was giving no serious indication that lightning may occur. Fortunately, it was a late Monday afternoon, and no one was in danger.

The lightning ripped through the length of the tree, severing some of its roots and blew a hole in the ground. There is charred bark on the opposite side of the hole.

 

The strike also blew out a nearby sprinkler head and sent an electrical short through irrigation communication wires all the way back to the shop. It's very difficult to determine the fate of this tree at this time. There is little structural damage to the canopy and trunk, but because the bolt damaged the root systems, there is a good chance we will see decline over time. Lightning damage on trees is very inconsistent - some trees can out grow it, others die immediately, and some do well for a few years and then suddenly die. We are taking a hard look at the damage and will watch it closely. There may be broken limbs that we can't identify until the leaves die off, so we have roped off the base of the tree as a precautionary measure.

There is literally endless information about lightning on the Internet, and a quick search in Google provides more than enough facts to make you think twice about it. Below some interesting facts worth reading. 

     *When you hear thunder (even faint thunder) you are in danger of a lightning strike. When the leading edge of a thunderstorm is within 10 miles you are at immediate risk due to lightning's out reach. In fact, many lightning deaths and injuries occur with clear skies directly overhead.
    * Many cloud-to-ground lightning flashes have forked or multiple attachment points to earth. Tests carried out in the US and Japan verify this finding in at least half of negative flashes and more than 70% of positive flashes. Many lightning detectors cannot acquire accurate information about these multiple ground lightning attachments.
    * Lightning can travel over the surface of the ground and through the ground. The ground surface can be lethal for up to 60 feet radius or more from the point of contact.  This also includes a ground rod as the point of contact.  In water, the lethal radius is about 600 feet from point of contact.
    * The temperature of lightning's return stroke is (5) five times hotter than the surface of the sun. It can reach about 55,000 degrees Fahrenheit in contrast to about 10,000 degrees Fahrenheit for the surface of the sun. This high temperature will immediately turn water or water vapor into high pressure superheated steam. This high pressure steam can explode the clothes off your body, explode the bark from a tree, explode concrete, drywall, wood or any material containing even small amounts of moisture.
    * About 20 million cloud-to-ground lightning strikes occur annually in the USA. That's just under one per second for the USA and about 100 per second world wide
    * Typically, more than 2,000 thunderstorms are active throughout the world at a given moment, producing on the order of 100 flashes per second. 
    * A lightning flash is composed of a series of strokes from about 3 to 20, with an average of about four. The duration of each lightning stroke can vary, but typically average about 30 microseconds. (The average peak power per stroke is about 1012 watts.
    * The energy contained in a single lightning stroke can power a 100 Watt light bulb for 90 days, which is equivalent to 215 kWh (kilo-Watt hours).
    * About 1% of the energy in a single lightning stroke is converted to electromagnetic energy. This can be thought of as having about 200,000 clear channel 50 kW radio transmitters all turned on at the same time feeding one antenna. The wave front can propagate half way around the earth.
    * U S Department of Agriculture estimates that lightning causes over 80 percent of all accidental livestock deaths.
    * The US averages about 100,000 thunderstorms each year (LPI)
    * The danger of lightning is often under publicized and misunderstood because it usually kills people one at a time. Lightning is one of the most dangerous features of a thunderstorm.

Finally, please take lightning very seriously on the golf course. The golf shop and grounds department are always on top of the current conditions and have a watchful eye on the radar. When the horn sounds, shelter should be taken, and when you see staff on carts racing west from the proshop, it is definitely time to pack it in. Hitting just one more shot or finishing the hole is very tempting, but ask yourself is it really worth it...

You wouldn't want to be putting the flagstick in a millisecond before this happened!