Lightning Distance Calculations

[Guest Sundancefisher]

This article below says one second is 300 meters then 5 seconds is 1.5 kilometers. Knowing lighting can travel much further I am still wondering why as a kid I was told 1 second was one kilometer.

 

Anyone now what is the best estimate of distance using flash to bang calculations?

 

Cheers

 

Sun

 

 

 

 

 

Safety - Lightning Calculation

Lightning - summer’s biggest light show - causes worker fatalities and injuries every year. Electrocution death, burns and brain damage are some of the effects. Lightning risks vary from one region to the next, from job to job and seasonally, but lightning safety knowledge is a good survival skill for everyone.

Most thunder and lightning storms occur during summer afternoons. Although individual fatalities are most common, almost 10 percent of incidents involve multiple victims. To estimate how far away lightning is, count the seconds between the flash and the sound of thunder. Each second is about a fifth of a mile, or 300 metres. If you count fewer than five seconds (a mile) take shelter immediately. This is known as the “flash to bang” method of calculation.

 

Outdoor workers are at a particular risk for lightning strikes. Danger zones include open fields, and areas below solitary tall objects such as trees, near power lines and fences. Avoid metallic objects, high ground and proximity to other workers. At the first sign of thunder or lightning, move to a substantial building. Ensure the storm has moved out of the immediate area before resuming work.

 

If you are caught outdoors during a lightning storm, avoid any objects which are likely to attract an electrical charge. This would include tractors, power tools, motors, tools such as shovels, and tall objects such as power lines or canopies.

 

Look for a low area such as a ditch. You don’t want to be the tallest object in the area. If you are caught in the open, crouch down with your feet together. Do not lay down flat. You need to minimize your contact with the ground to lessen the risk of electrocution.

 

If you are indoors during a lightning storm stay away from doors, windows, water, plumbing, electrical appliances, computers and televisions. Lightning can strike power, telephone and cable lines, transmitting a jolt through telephones, TVs and electrical equipment.

 

If you are driving a vehicle, pull off the road in a location away from trees which might fall on you. Turn on the emergency flashers and turn off the engine. If you are in an enclosed metal frame vehicle, stay there. Do not touch metal objects connected to the outside of the vehicle – door, window handles, steering wheel or radio controls. Instead, sit with your hands in your lap.

 

If you are operating enclosed heavy equipment such as a backhoe or grader, turn off the engine and wait out the storm with your hands in your lap. Do not attempt to step off the equipment during a close lightning storm.

[TerryH]

It all has to do with the speed of sound. You see the flash at virtually the same instant that it happens, since the speed of light is so fast. The speed of sound varies according to temperature, atmospheric pressure, and humidity, but under "normal" summer conditions it is around 340 m/s. Therefore, for the sound to travel 1km, it will take 1000/340 = 2.94 s, or around 3 seconds. Terry

[Guest Sundancefisher]

It all has to do with the speed of sound. You see the flash at virtually the same instant that it happens, since the speed of light is so fast. The speed of sound varies according to temperature, atmospheric pressure, and humidity, but under "normal" summer conditions it is around 340 m/s. Therefore, for the sound to travel 1km, it will take 1000/340 = 2.94 s, or around 3 seconds. Terry

 

Makes perfect sense now...

 

Dam physics... :-)

 

Thanks.

 

Sun