DISSECTED: DARKNESS BY DAY  

Calcutta: Streaks of lightning coursing through an almost pitch-dark morning sky to the accompaniment of deafening drum rolls of thunder on Monday infused fear and enriched the city's monsoon lexicon.

Astraphobia (from the Greek word astrape) defines the "fear of thunder and lightning", a feeling that possibly did not escape anyone who might have been outdoors in the morning.

Shami Das, a 25-year-old contract worker with Jet Airways, was so traumatised by a bolt of lightning striking the airport tarmac a few metres from where he stood that he needed to be hospitalised.

The young man was near parking bay 8, his hand touching the step ladder that passengers use to climb up or down an aircraft, when a flash of light landed on the turf. "He let out a scream and fell on the ground," an official recalled.

Shami was taken to the airport's medical unit for an examination that confirmed he was safe. "His body had no sign of any burn injury. He was simply traumatised," said a doctor at the unit.

He was admitted to the ESI Hospital in Maniktala, where an echocardiogram was done to check for any stress damage to the heart. "No medical anomaly was found there either," the doctor said.

Shami's trauma is understandable after the lightning tragedy that occurred in the city just over two weeks ago. Debabrata Pal, a 21-year-old cricketer, was struck by a bolt of lightning and killed on June 10 while warming up for nets at a Vivekananda Park camp.

Met officials said a mass of tall cumulonimbus clouds, which are more a summer feature, caused a spell of thunder and lightning on Monday that lasted long enough to scare the living daylights out of many people.

"My elder son Shubham woke up with a start around 8.30am. I have never seen him so stunned," said Vinod Mathai, a resident of the Kasba neighbourhood.

In an Entally home, Pixel, a five-month-old Lhasa Apso, froze when a flash of light lit up the room. The accompanying thunder sent the pup scampering under the bed, shaking in fright. Pixel's owner had a hard time coaxing him to come out. The family's other two pets, a Lhasa Poodle and a Cocker Spaniel, wouldn't stop barking.

The thunder led to other kinds of disruption as well. The intranet server at the ESI Hospital in Maniktala was damaged by lightning, forcing the authorities to switch to manual registration of patients for two hours.

The Met department does not maintain records of thunder and lightning, but 2018 has had more episodes of prolonged thunder and lightning than in recent years.

Thunder and lightning occur when a powerful charge is created inside clouds because of the collision of ice particles and supercooled water. The pace at which particles moved inside the clouds on Monday might have been higher, resulting in the accentuated thunderstorm activity, a weather scientist said.

Sanjib Bandyopadhyay, the deputy director-general of the India Meteorological Department, Calcutta, said people might be feeling there has been more thunder and lightning this year because the number of thunderstorms have increased from five to six during the season to about 10 to 12 this year. Thunderstorms have continued during the monsoon.

Why was the sky so dark?

• A mass of 5-6km tall cumulonimbus clouds along with altostratus (middle altitude) and stratus (low-hanging) clouds shut out the sun’s rays, causing the effect of dusk by day.

Why doesn’t this happen always during rain?

• Cumulonimbus clouds are common in summer while altostratus and stratus clouds are typical of the monsoon. They occurred together on Monday morning, which is rare.

How much did it rain?

• Rainfall was uneven, varying between 24mm and 82mm. In meteorology, the threshold for “heavy rain” is 60mm.

What is on the radar?

• Rain will continue for now as the flow of the monsoon winds that bring moisture to land from the Bay of Bengal is strong. Heavy rain is forecast for Tuesday.

Rith Basu