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Lightning Dangers


Michael Dell
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Most of us are likely Guilty. I usually wait until I actually see lightning. On a lake if I see nastie weather coming I will usually head in, But as the article says we likely wait just a bit to long to get that line out of the water.

 

Tight Lines Always

Dennis S

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Guys

 

Lets take this a bit further and see if anyone can find an article or two as to what to do if you are caught in a lake or stream and a lightning storm is around you.

 

Like others I've waited far too long and have been far to close to lightning while on a stream. Thanks for the article Michael.

 

Vince

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It's common knowledge that lightning tends to hit the highest objects in an area. That's not always true.

One way is determine if you are vulnerable is to imagine a ball 90m (270ft) in diameter rolled around the ground. Any place it touches is a potential strike point. So you see if you are more than about 150 ft (1/2 a football field) from something taller than you are, then you are a potential target. If you are waving a good conductor around over your head (like a graphite or wet cane rod) the odds go up dramatically.

Thus anyone on a boat in the middle of lake could easily get zapped. So if you see or hear a storm coming get the HE double hockey sticks off the lake!! And factor in the time it takes to get to shore (worse in a kickboat or float tube than in a motorized watercraft)

Another common myth is that lightning has to come directly down from a cloud. 'Taint so, While rare, lightning can travel a few kilometers from the cloud in open sky before hitting something. So just because you think the storm isn't overhead doesn't mean you're not at risk.

There is a rule of thumb that if you count the time from the lightning flash to hearing thunder and divide by 7 that tells you how many miles the lightning is away. Bad idea!! Lightining regularly occurs at 35000 ft (almost 7 miles) above ground. So forget the first 7 seconds plus add another 14 for clear air bolt travel distance. Any count less than 1 minute is Too D@mn Close!

For protection you need to get out of an exposed location. That means reducing your height above the surrounding terrain. You should try to moderately close to a substantial structure. The high point will provide a cone of protection of about 30 degrees.

It doesn't mean taking shelter under a tree. If the bolt hits the tree, It can explode and impale you with splinters. Avoid power and telephone poles too.

Getting lower doesn't mean lying down either. The voltage gradient in the earth can cause current to flow through your body, even if the bolt doesn't strike you but hits close by. You need to squat down and minimize your footprint on the ground.

Being inside your car is not a bad idea unless your car is the tallest thing around. (remember the 90m ball?)

The key thing is to watch the weather. Any indication of a thunderstorm headed your way means get off the lake, under cover, in your car or somewhere you are not exposed right away!!!

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I've never heard that 7 second rule, Dave. I was always told 5 seconds to a mile. Sound actually takes about 4.8 seconds to travel a mile (2.9 sec/km) so I figured 5 was close enough. Maybe 7 accounts for the hypotenuse. ;)

 

Truth is, in our part of the world the base of a thundercloud is usually around a mile up. The base of the cloud is where the downward leader begins to head for the ground, while the upward leader heads for the top of the cloud. Thunder is created almost simultaneously along the length of the discharge channel, so the length of time the thunder rolls corresponds to the difference between the lightning's closest point to you and the furthest. So the 5 second rule seems to hold up.

 

A thundercloud a mile up could easily produce lightning that strikes more than a mile away, possibly 2 miles. In the tropics, where the base of the cloud might be 5 miles up, sure it could reach out 7 miles to the side. With a clear line of sight, lightning can be seen from 15 miles away, and heard from 12. I govern myself accordingly.

 

Next you'll be telling me I shouldn't go fishing alone in bear country.

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Yes, the speed of sound at 20C is roughly one mile in five seconds. However, when mentally counting, almost everyone counts seconds too fast.

The 1 -1000 or 1 hippopotomus mantra helps, but only if you count out loud. The 7 count rule of thumb accounts for that discrepancy.

Theres no clear answer on which strike leader goes in which direction. I've seen video and research papers that are contradictory.

In general there are three charge layers. Two in the cloud, produced by charge transfer in droplets and other particles in updrafts and downdrafts and one in the ground produced by electrostatic induction. The bottom charge layer in the cloud is negative (meaning an excess of negative ions) The theory is that the excess negative ions (being more mobile than the positive ions in the ground) migrate towards the ground due to attraction to the ground charge and are met by a postive ion leader from the ground migrating towards the cloud. When they meet - Zap! That changes the cloud charge which causes another zap to the upper cloud charge layer. That can initiate another charge change that casues a bolt from the upper layer to the lower cloud layer and then another zap to the ground. Because of the repeating phenomena it's hard to isolate which comes first for an individual ground strike. Most thunderstorms have almost continuous charge transfer and repeated lightning from charge layer to charge layer, The charge layers cover an immense area and there can be charge exchange between thunderstorm cells as well.. In large weather systems, interrelated lighting and charge trasfer can occur over distances of hundreds of kilometers (supported by movies from the space station)

 

And you are welcome to go fishing alone in bear country. Bears gotta eat too.

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Here we go again....the science is cool but is really of no use to me...sorry. What I want to know and I think a lot of others want to know is what do we do if we are caught in a thunderstorm and are on a small creek, river or lake other than to have gotten the hell out earlier. Where and how do we seek safe shelter ?

 

Vince

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If you are caught by surprise and the storm is close:

 

On land - Get out of the water. Put your fly rod down and don't touch it. Squat down, feet together, as low as possible. Do not lie down.If you have time, find a slight depression or low point in the surrounding landscape. Stay away from tall trees and power poles.

 

On a lake. - Put your fly rod down and don't touch it. Crouch as low as possible in the boat. Don't lie on the bottom.If you have time, get to shore and find a slight depression or low point in the surrounding landscape. Stay away from tall trees and power poles.

 

Wait for the storm to pass a significant distance away (several miles) before resuming fishing.

If your hair starts standing on end or you see blue discharge from your fly rod,

Put your head between your legs and kiss your butt goodbye.

 

Dave

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Dave

 

Now that's what I call an answer....right to the point.

 

In many of the streams I and others fish the stream flow is but a yard or two from the tree line so the question is do we hunker down near the stream in a low point or near the tree line in a low point.

 

Vince

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As you all know the weather can change very fast on any lake , tim bitts and the fat guy would take to long to set the bait .

I always watch for clouds , it gives you a good indicator as to whats going to happen .

My rule is High winds + Heavy clouds = Get - off the Lake period !

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Very interesting discussion.

 

Another approach is to improve your peronal forecasting skills. On a lake, keep an eye on the sky and learn the prevailing direction of the weather. The typical thunderstorm is an afternoon event not likely to take anyone by surprise. I do get off the water when I hear thunder. I also shorten the distance between me and shelter ahead of time if the weather looks threatening. That is, row closer to the boat ramp/dock before I even hear thunder. Also, the timing of thunderstorms follows a fairly regular pattern as you move away from the foothills where they usually build. For a quick trip from home, check the radar before leaving, you may be able to fish the clearing right after a storm.

 

The weather is also pretty regular in a set location. Use your past experience to learn the weather patterns on your favourite water. I pretty much stay away from the Rocky Mountain House to Red Deer corridor in June-July. I am sure to be missing on some good fishing, but I do get to fish another time...

 

On a river, in the forest, hidden in a valley it is harder to tell, but the sky is still visible and thunderstorms are more clearly defined closer to the mountains. The timing is also more likely early to mid-afternoon. If there is a chance of electrical activity in the near future, I do not go far, or stay in and tie flies.

 

The tricky ones are the electrical storms that develop within overcast rainy weather. Rarely, these roll through in the morning. If you are not sure of electrical activity, use a lighning detector or a radio tuned between stations on the AM band. If it is all clear, then head out. Otherwise...

 

Finally, some of the best fishing is between late September until late April, including warm days in January. No lightning, no mosquitoes, no high UV, no excessive heat, no murky water, not even bears if you shrink the window a little more (but then it is also closed on many streams). If you are like me and do not enjoy hot and humid, then you are even less likely to get too close to funny weather. See example of good weather below.

 

post-78-0-65813400-1373431680_thumb.jpg

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No need, it shows the same all summer long... :bigsmile:

 

On a more serious note, there used to be a map of lightning strikes as they were occuring.

That seems to be gone, but there is the following http://weather.gc.ca/lightning/index_e.html

for those of you with phones and data access in the woods.

There is also http://weather.gc.ca/radar/index_e.html?id=WHK for home-range trips and,

for longer-range planning, I use http://www.wxmaps.org/pix/prec2.html

 

All good stuff, who needs to go outside anymore?

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