Why doesn't lightning travel in a straight line

In the past, I have few attempts at shooting the lightning as it happen and none of my shots are decent enough, but one thing I observed is that lightning does not travel in a straight line.

Captured with Nikon D90 at | 38mm | f/18 | ISO-200 | 30 sec |

First, how lightning is formed

The zig-zagging path of lightning has its origin in processes still not fully understood. It begins with strong rising currents of air creating a static electric charge through frictional effects somewhat like those on the surface of balloons rubbed on suitable fabric. Recall the Van der Graaff effect?

This charge generates an electric field that accelerates any free electrons in the surrounding air, smashing them into neighbouring molecules, thus releasing yet more electrons.


. . . and the zig-zag?

If sufficiently violent, these collisions will turn the air under the cloud (see pic above) from electrically insulating to conducting, which allows the passage of electrical current. This heats up the air to around 30,000^oC, triggering the characteristic flash light that follows the zig-zag path formed by the collisions.

The heat also causes a sudden expansion of the air, which we hear as a clap of thunder. The thunder 'loudness' corresponds with the amount of electrical current passing through the air.

In short: Molecules and electrons collisions are in random directions, so the lightning flash you see in the sky is not in a straight line, too.

LED : Lighting the Future

It is very interesting to note that the country intends to use Light Emitting Diode, LED to light up its streets by 2014.

Light-emitting diodes (LED) are solid-state devices that convert electrical energy directly into light of a single color. LED do not waste energy in the form of non-light producing because they employ ‘cold’ light generation technology, in which most of the energy is delivered in the visible spectrum. It could offer long service life and high energy efficiency, although at this juncture, initial costs are higher than those of fluorescent and incandescent lights.

LED street-lighting: Image - Soltron Corp.

Although costlier, LED's offer a variety of advantages compared to conventional lighting; among the more commonly known are:

Long-lasting

LED light can last up to 50,000 hours or 10 times as long as compact fluorescents, and far longer than the conventional incandescent. Very little maintenance is required through out the life span of the lamp.

Durability

LED are filament-free, solid and robust. Thus, they are not easily damaged under the same circumstances where regular incandescent bulbs would.

Environmentally Friendly

No mercury. More environmental friendly. LED's are made of non-toxic materials, unlike fluorescent lights that contain huge amounts of mercury and other hazardous material.

Cold Temperature Operation

Cold temperature is one of the challenges of fluorescent lights. On the other hand, LED light output and efficiency increase as operating temperature drops, making LED a natural choice for refrigerators, freezer cases and cold storage facilities.

More efficient

LED light produces more light per watt compared to incandescent light, a feature that would be useful in battery powered devices. In addition, LED light can emit an intended color without the use of color filters employed by traditional lighting methods. The following Table shows the comparison of the equivalent wattage and light output of Incandescent, Compact fluorescent, and LED lights.

Table 1: Equivalent wattage and light output of Incandescent, fluorescent (CFL), and LED Lights


LED lights are fast becoming the light source of choice for many general lighting applications, such as architectural lighting, down lights, freezer case lighting and retail display lighting. Even street illumination using LED is quite a common sight nowadays. Due to the low power consumption of LED lights, they can be solar powered and installed off-grid at remote locations.


General Lighting Term used

• Illumination:  The distribution of light on a horizontal surface.
• Lumen:  A measurement of light emitted by a lamp
• Efficacy: The ratio of light produced to energy consumed. It is measured as the number of lumens produced divided by the rate of electricity consumption (lumens per watt)
• Color Rendering Index (CRI): The Color Rendering Index (CRI) is a 1–100 scale that measures a light source’s ability to render colors the same way sunlight does.

Reference: Buletin ST, Issue No.1, 2012

Why do we get electric shocks from static?

Static builds up on the surface of good electrical insulators like glass, Teflon, paper, plastics, to name a few. Such materials build up charge readily because they don't conduct it away.

Natural example of static discharge. Shot with Nikkor 24-120 F4 at 120mm | f/7.1 | 30sec | ISO-200 |

It is called static because accumulated charge gets ever greater until something comes along to conduct it back to earth. We become that conductor when we feel the shock from touching the object. If the accumulated charge become so great, the discharge through the conductor - in the case that it is the human body - can be fatal.

Could lightning be used as a source of energy (RE)?

In my previous article, I was talking about harnessing energy from the blowing wind. We do that by putting up wind turbines or mills.

How about lightning? Can we harness its seemingly huge amount of energy burst into something useful, so that we get a sustainable source of energy?

Lightning strike captured from Suria Sabah shopping mall - Dec 21, 2009

The answer is no, that's at least for now. In future - and I mean not in the near future - who knows, someone could just pop up from somewhere and come out with the big idea.

With around 16 million storms worldwide each year, plus a typical lightning bolts unleashing around 500 million joules of energy, lightning certainly looks impressive! But despite the big number scientists say that all it does is power up an equivalent of 2 households for a day. 

Why so? Because lightning doesn't produce energy. The massive sound and lights you see in the sky is just a process of 'transferring' energy. The energy you could get from the lightning is less than the energy it would take to create some sort of massive negative charge to produce energy.

You can further read here, but to make the story short, as a source of reliable energy, lightning is hopeless. You'd better be worrying about avoiding a lightning strike, than to spend your precious time trying to harness it to provide electricity for your home.