Lightning And Thunder: What Are They and What Do They Want? by Marjorie Dorfman
Have you ever wondered about where lightning and thunder come from? Atlas crying out to the heavens and protesting the weight of the world on his shoulders was never a reasonable explanation for me, as I am sure it isnt for most people. Read on for more information about these two natural phenomena but whatever you do, dont run under a tree!
There are few who would argue that lightning is the most spectacular element of any thunderstorm. Lightning and thunder never make solo appearances; they always come together in one wet and very powerful package. Lightning is actually a giant spark and one single stroke can heat the surrounding air to 30,000 degrees Celsius (54,000 Fahrenheit)! This causes the air to expand and creates a shock wave that transforms into a booming sound wave, known to those whose eardrums remain intact as a thunderstorm.
The mechanism that leads to lightning is complicated and not well understood. The sky is always electrically charged. In a calm sky, the + and charges are evenly interspersed throughout the atmosphere and a neutral charge prevails. When a thunderstorm is forming, the electric charge is spread out differently as the storm consists of ice crystals and hailstones. Simply put, the ice crystals have a + charge, while the hailstones have a charge. An updraft propels the ice crystals to the top of the storm cloud while the downdraft pushes the hailstones downward. Thus, the thunderstorms + and charges are separated into two levels: the + charge at the top and the charge at the bottom.
During a thunderstorm, an occurrence known as a "step leader" happens. What this means is that the charge at the bottom of the cloud grows and gains enough momentum to overcome air resistance and this is followed by a flow of charge that rushes toward the earth. When the step leader and the + charge from the earth meet, a strong electric current carries the + charge up into the cloud. This electric current is known as the return stroke of lightning and is visible to the human eye.
Contrary to what you might think and see, lightning and thunder do occur simultaneously. The reason there seems to be a time lapse between the former and the latter is because sound travels much more slowly, one mile in five seconds as opposed to lights 186,000 miles per second in a vacuum. The flash of lightning travels at about 93,000 miles per second in air. How could sound possibly win with such odds? Often sound does follow rather quickly, and sometimes as little as five seconds will pass before the flash of lightning is matched by the sound of thunder following which means the lightning struck only about a mile away. (Whats five seconds among friends?)
Sound is also detained because it tends to bounce off molecules in the air and travel in diverse directions. This means that the further away the source of the sound is, the more distorted it becomes. Following this line of thought, when you hear thunder rumbling, the lightning bolt was far away, but when you hear a crack or boom of thunder, the lightning bolt is much closer.
Most of the lightning in a storm occurs within a single cloud, but it can happen in several different spots as well. Lightning is able to jump from cloud to cloud and also into the surrounding air.
Although the most common manifestation of lightning appears as a single line of bright white light, there are several forms it can take. Some of these include: forked lightning, which appears to have branches, streak lightning, which is visible as a single wiggly line, bead lightning, where small sections of the channel remain bright longer than others, heat lightning, which often appears to be red and sheet lightning, which is caused by lightning occurring inside clouds.
There are different types of lightning. Intracloud lightning takes place entirely within one cloud. Its path usually extends about two miles, but it can be and sometimes is much longer. The second most common type of lightning is the cloud-to-ground formation, which is a discharge between a cumulo-nimbus cloud and the ground initiated by the downward-moving leader stroke. Triggered lightning is very rare and results from contact with a tall structure. Other formations include powerful superbolts and balls of lightning, which are often colored orange or red. Little is known about the nature of ball lightning.
And so my friends, lightning and thunder remain two powerful and mysterious forces of nature that keep all of us looking small when compared to the ocean.
Avoid trees when lightning strikes and from the safety of your dry interior
Anyone needing a clear exposition of lightning, how it is produced, the different types, and its dangers will find it explained here in cogent detail. Diagrams supplement the well-written narrative in describing scientific concepts. Exceptionally fine, full-color photographs each a work of art perfectly illustrate the text, powerfully and spectacularly showing the majesty and might of this phenomenon. Written material and pictures can stand independently, but together they create a masterpiece. Be careful! Your kid may get hooked and want to become a meteorologist or storm chaser!
Visit HobbyTron.com for a large selection of robot kits and projects.