| Ever since Benjamin Franklin flew his kite and | | | | series of steps as follows: |
| nearly blew himself up with the resultant lightning | | | | 1.Electrons surge downwards towards the ground |
| strike, we have been attempting to discover | | | | at a speed of 14,000 mph for around 200-300 |
| exactly how lightning works. A discharge of | | | | feet. |
| lightning is probably one of the most impressive | | | | 2.The electrons stop for a fifty-millionth of a |
| displays in the atmosphere, yet surprisingly, | | | | second. |
| despite years of study, the exact process is still | | | | 3.They travel on again for another 150-200 feet |
| shrouded in some mystery. | | | | 4.Positive ions start to move up from the ground |
| Lightning results from the build up of opposite | | | | from any protruding object such as a tree or a |
| electrical charges within a cloud. Ice crystals which | | | | golfer |
| form in the upper reaches of a cloud are generally | | | | 5.When they meet, a huge electric current flows |
| positively charged, and water droplets which sink | | | | carrying positive ions into the cloud. |
| to the lower part of the cloud, are usually | | | | These ions are carried on a channel a few |
| negatively charged. It appears that the ice | | | | centimetres wide and as they move upwards |
| crystals are positively charged as a result of | | | | they glow enough to be seen. So, like a giant |
| collisions, within the maelstrom of a thunderstorm, | | | | spark, the lightning travels upwards into the cloud |
| with warmer water droplets. When the warmer | | | | so fast that it is impossible to judge whether it is |
| droplet collides with an ice crystal it passes on its | | | | travelling up or down. Your typical lightning flash |
| positive charge, and consequently the water | | | | will consist of approximately 4 leaders and 4 |
| droplet is now negatively charged. | | | | return strokes indiscernible apart from the familiar |
| Okay, so, as the storm now tracks across the | | | | flashing. |
| land it is positively charged in its upper reaches | | | | Lightning is incredibly hot, five times hotter than |
| and negatively charged in its lower portions. | | | | the surface of the Sun at 30,000 degrees Celsius. |
| Because opposites charges attract a positive | | | | As a consequence the air around a bolt of |
| charge now builds up on the surface of the land | | | | lightning expands in an explosion that causes a |
| directly below the storm. However, the air is an | | | | massive shock wave. This shock wave travels |
| excellent insulator and initially stops these charges | | | | through the sky as the sound of thunder. |
| from joining each other. But as the potential | | | | Because, relative to light, sound is very slow |
| difference builds between the cloud and the land | | | | moving you can calculate how far away a lightning |
| eventually the inevitable happens and the air can | | | | flash is by measuring the length of time between |
| no longer hold back the negative electrons and a | | | | the flash and the thunder. Every 3 seconds |
| process known as the 'stepped leader' occurs. | | | | counted is roughly half a mile away. But |
| In the 'stepped leader' a succession of steps are | | | | beware...the danger zone for a lightning strike is |
| followed. The electrons do not flow in a steady | | | | within 6 miles of the storm! |
| and continuous manner but in a more erratic | | | | |