The phenomenon of thunderstorm and lightning A thunderstorm is a storm associated with lightning and thunder.
They are typical atmospheric phenomena and tend to be highly localized. It is generated within the clouds and thus prevention is beyond the human control. From a pure disaster management point of view, the main hazard is lightning and not the thunderstorm.
Thus, in this article, we shall focus more on the hazards caused due to lightning.
Thunderstorm forms within a warm, moist air rising in an unstable environment. As long as rising air becomes warmer (less dense) than surrounding air, there is an upward-directed buoyant force acting on it. The warmer the air as compared to its surroundings, the greater the buoyant force and the convection. The triggering forces needed to start air moving upward can be one of the following
1) Random, turbulent eddies that lift small bubbles of air
2) Unequal heating at the surface
3) The effect of terrain (such as small hills) or the lifting of air along shallow boundaries of converging surface winds
4) Large-scale uplift among mountain barriers and rising terrain
5) Diverging upper-air level winds, coupled with converging surface winds and rising air
6) Warm air rising along a frontal zone
Normally, combinations of these phenomena trigger with vertical wind shear to generate severe thunderstorm.
Lightning is a discharge of electricity, a giant spark which usually occurs in the mature thunderstorms. Lightning may take place within a cloud, from one cloud to another, from a cloud to surrounding air or from a cloud to the ground.
Lightning results from a strong separation of an electric charge that builds up between the top and bottom of cumulonimbus clouds).
Air carrying water droplets and ice particles move towards the top of the cumulonimbus clouds where they clash with the downward moving ice particles or hail.
In this process, a strong positive charge usually carried by the top of the cloud interacts with the lower part of the cloud which carries a strong negative charge. Negative and positive charges attract one another; a negative electrical charge may attract the positive-charged cloud top or to the positive-charged ground.
This generates electrical charges in terms of millions of volts. At one point of time the electrical resistance in the air cannot keep these opposite charges separate from each other; it results in positive and negative regions joining with an electrical lightning strike.
A person standing on the ground will always see ‘Lightning’ first and then hear the ‘Thunder’ sound though both occurs at the same time. This is due to the fact that light travels at a speed of around 300,000,000 metres per second while sound which travels at a speed of 340 metres per second. So the light is visible before the lightning sound.
Impact of Lightning
The critical impact of lightning is death and injuries, but more than that, economic damages arising out of lightning are worth mentioning. Lightning causes damages worth of billion rupees in the Housing, Agriculture, Industrial and Public Sectors. Lightning strikes can injure humans in the following ways.
Direct Strike – The person falls in the path of the lightning strike. Due to the passage of enormous energy through the body, this kind of event results in severe burns and damaged nervous system, and is often fatal.
Contact Injury – Occurs when the person touches any object which was electrified by the lightning strike
Side Splash – Branches coming off from the primary flash channel injuring the person.
Blast Injuries – Occurs when the person is impacted by the blunt force trauma of the lightning strike
Lightning is a common occurrence, especially in tropical and sub-tropical regions which results in the
massive number of deaths per year. It occurs intermittently throughout the year. Global estimates
range from 6000 to 24000 fatalities per year due to lightning strikes But it is to be noted that there has been the little systematic collection of information on lightning deaths in many
regions of the world making it difficult to give correct estimates.
Lightning study Centre (LSC)
In order to prevent losses due to lightning incidents in the country , it is of urgent necessity to establish a dedicated Lightning Study Center (LSC) that could actively involved in conducting research, awareness programs and information dissemination for lightning protection. The LSC will be able to work with international institutions/individuals and other regional organizations in close coordination. Through collaboration with entrepreneurs, LSC will be able to provide solutions of lightning protection at various levels. Sensitization of bureaucracy and engineers regarding lightning risks, lightning safety and protection can also be conducted by LSC.
Do’s and Don’ts on Thunderstorm and Lightning
If you are outside
- Go Inside when Thunder Strikes
- Stay Individual, Stay Safe
- Do not lie down in open, Rush to a Safe Shelter
- If caught in Lightning, Bent down yourself in a rounded shape
- Keep away from Trees or open areas , prevent disasters
- Mountain tops or Highlands are dangerous during the thunderstorm, get down immediately
- Flying Kites or playing in open areas may be dangerous! Avoid doing so.
- Avoid using Umbrella, Fishing Rods, Metal Sticks etc.
- If you are in water or Swimming pool during the thunderstorm, immediately rush out.
- If you are in Boat/Steamer, go ashore to a safe shelter
If you are Inside
- It’s dangerous to use plugged in Telephone or Electric /Electronic Appliances –Avoid using them during lightning and thunderstorm.
- Avoid using all the electric appliances or wired gadgets during thunderstorm and lightning .
- Install ‘Lightning Conductor’ in your house/office/other installations . It can save you .
- Moving Barefoot inside the house may be dangerous wear rubber slippers.