Lightning

An electrical discharge between clouds or between a cloud and the ground, caused by charge separation in thunderstorms. Lightning kills more people in India than any other weather hazard.

phenomena

What is Lightning?

Lightning is a massive electrostatic discharge in the atmosphere, accompanied by the sudden flash of light and the sound of thunder. A single lightning bolt carries roughly 300 million volts and 30,000 amperes, with a peak temperature near 30,000°C — about five times hotter than the surface of the Sun.

Lightning is the deadliest weather hazard in India, killing more people each year than cyclones, floods, heatwaves and earthquakes combined. The National Crime Records Bureau reports an annual toll of 2,000–3,000 deaths, with most victims being farmers and outdoor workers in central and eastern India during the pre-monsoon and monsoon thunderstorm season.

How lightning forms

Inside a tall cumulonimbus thunderstorm cloud, strong updrafts and downdrafts collide ice crystals, supercooled water droplets and graupel (soft hail). The collisions transfer electrical charge:

Lighter ice crystals become positively charged and rise to the top of the cloud.
Heavier graupel particles become negatively charged and accumulate at the base.

When the voltage between regions of opposite charge exceeds the insulating capacity of air (about 3 million volts per metre), an electrical breakdown occurs — a lightning bolt. The discharge can be:

Intra-cloud (most common, ~75%): between charge regions of one cloud.
Cloud-to-cloud: between separate clouds.
Cloud-to-ground (most dangerous, ~25%): the type that kills people and damages property.

Cloud-to-ground lightning often “steps” down through the atmosphere in a series of branching channels until it makes contact with the ground, then returns upward as a brilliant return stroke.

Lightning in South Asia

India experiences roughly 18 million cloud-to-ground strikes annually according to NASA’s Earth Observatory. The pattern:

Pre-monsoon (April–May): Severe thunderstorms across eastern India — “Kal Baisakhi” or “Nor’westers” in Bengal, Bihar, Odisha, Assam.
Monsoon (June–September): Almost daily storms across the subcontinent.
Post-monsoon (October–November): Coastal Tamil Nadu and Andhra Pradesh.

Highest-density lightning regions:

Eastern India: Bihar, Jharkhand, West Bengal, Odisha (the so-called “lightning corridor”).
North-east India: Meghalaya, Assam, Tripura.
Central India: Madhya Pradesh, Chhattisgarh.
Pakistan’s monsoon plains: Punjab, Sindh.

Bihar alone reports 300–400 lightning deaths each monsoon season, the highest of any Indian state. Most victims are farmers caught in fields or under trees during sudden storms.

Lightning safety — the 30/30 rule

The single most important safety rule: if you can hear thunder, you are within striking distance. Lightning can strike up to 15 km away from the parent storm.

The 30/30 rule used worldwide:

Count the seconds between a flash and the thunder. If less than 30 seconds, the storm is within 10 km — seek shelter immediately.
Wait 30 minutes after the last thunder before going back outdoors.

Safe places during a thunderstorm:

Inside a fully enclosed building (most homes, offices, schools).
Inside a hard-topped vehicle with windows closed (the metal cage conducts current around occupants).

Dangerous places:

Open fields, beaches, mountaintops, rooftops.
Under isolated trees.
Near tall metal objects (electric poles, lamp posts).
In or on water (swimming pools, lakes, boats).
On telephones with cords, in showers, or touching plumbing.

Special advice for farmers (the largest lightning-victim group in India):

Stop work and seek pukka shelter at the first rumble of thunder.
Crouch in the lowest spot if no shelter is available, feet together, hands over ears.
Never lie flat on the ground — that increases your contact area.
Do not seek shelter under solitary trees — the most lethal location.

Indian government early-warning system

The Indian Institute of Tropical Meteorology (IITM) Pune operates the Damini app which provides 20–40 minute lightning-strike forecasts based on a national sensor network. The IMD also publishes severe-thunderstorm warnings on its Sachet app and through state disaster authorities.

Mausam Online does not yet display lightning-density forecasts but shows precipitation probability and severe-weather alerts on each city page — useful precursors during pre-monsoon and monsoon thunderstorm season.

Frequently asked questions

How many people die from lightning in India each year? Around 2,000–3,000 deaths annually, with Bihar, Madhya Pradesh, Odisha and Jharkhand bearing the highest toll. Most victims are farmers and outdoor workers struck in open fields.

Is it safe to use a mobile phone during a thunderstorm? Wireless mobile phones are safe to use indoors. Landline phones with cords are not — the cord can conduct lightning current into the building.

Can lightning strike the same place twice? Yes — tall objects (Eiffel Tower, Empire State Building, mobile towers) are struck many times each year. Lightning seeks the shortest path to ground, and tall objects offer that.

What’s the difference between thunder and lightning? Lightning is the visible electrical discharge; thunder is the sound produced by the rapid expansion of air superheated by the bolt. Light travels faster than sound — that’s why you see the flash before hearing the boom.

Where can I monitor thunderstorm risk for my city? Mausam Online’s hourly forecast shows precipitation probability and severe-weather codes (95–99 = thunderstorm) on every city page. See Patna, Kolkata, Bhopal, Raipur.