You can teach your kids about weather and lightning with the lightning lab.
What has been figured out so far is that the charge builds up through a process called polarization. This happens in the clouds by another process similar to frictional charging, caused by the collision of water and ice particles. Now the electrical polarity of the clouds tends to be negative at the bottom and positive towards the top of the clouds.
Now that the clouds have started to polarize it builds an electrical field which in turn affects the charge of the earth in a localised area. The negative charge at the bottom of the clouds repels the electrons in the earth to create a positive charge at the surface. As the charge in the clouds increase it reaches a point where the water vapour can no longer hold any more charge, this is called the dielectric constant. This is the point where the cloud will discharge in the form of a bolt of lightning.
Normally air is a great insulator of electricity and it is relatively difficult to get a strong arc through the air, especially when you’re talking about distances that lightning travels. In this case though the air becomes a lot more conductive due to the strong electric field which is strong enough to ionize the air. The lightning bolt starts off as a step leader which is the excess electrons that have built up making their way through the polarised and now conducting air.
The electrons at this stage are travelling at about 95 km (60 miles) per second, which is nothing compared to the speed of the lightning bolt itself. Now is when we start to get a positive charge moving up from the ground to meet the descending leader. Often the positive charge will move up through buildings, trees and even people. When the positive charge starts ascending it is called a streamer. When the Streamer and Leader meet the connection point is normally pretty close to the ground sometimes up to 100 metres (300 foot) high. Now that a complete conductive pathway has been established the discharge starts and you have lightning.
A few Interesting Facts about Lightning:
- Lightning raises the temperature of the air immediately around it up to 27,000 degrees Celsius (50,000 F). Which is about 5 times hotter than the surface of the sun.
- The odds of being struck by a bolt of lightning in your lifetime are approximately 3,000 to 1.
- In the Last 50 years there have been nearly 4,000 people killed by lightning strikes.
- The average lightning bolt has about 10000 Amps at 100 million Volts.
- Normally a bolt of lightning actually consists of 3 - 4 discharges or separate strikes.
- Most lightning strikes are a negative charge discharging to the positive ground.
- There is also positive charge lightning strikes which make up about 10% of all lightning strikes, these positive lightning bolts are also 10 times more powerful than the average negative lightning bolt.
Get your kids into science with the great range of kits from the Magic School Bus.
For other fun facts about science visit Fun Science Facts.
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