A significant increase in lightning during rains

[Wrichik Basu]

This year in Kolkata, we are facing severe trouble from lightning. In the previous years when it rained, lightning was much less. This time, even before it starts raining, lightning starts, and it reaches the ground, taking lives. As soon as the clouds start appearing, lightning bolts reach out to the ground or tall buildings. Till date, 28 people have lost their lives due to lightning in Kolkata and surrounding regions.

Pollution is a increasing problem in almost all metropolitan cities, including Kolkata. Can this sudden increase in lightning strikes be accounted by the pollution? Or is their some other explanation for this rise?

 

[rootone]

Has the temperature this year been higher generally?
The are many factors which contribute to formation and intensity of thunderstorms, but higher temperature is a big factor.

 

[davenn]

In the previous years when it rained, lightning was much less. This time, even before it starts raining, lightning starts, and it reaches the ground, taking lives. As soon as the clouds start appearing, lightning bolts reach out to the ground or tall buildings.

a strange comment to make ??

you are not going t o get lightning without thunderstorm clouds

rootone's comments are good. Changes to local climate may well be increasing the formation of thunderstorms
I doubt that increased air pollution is the cause. You still need the storms to build up before there will be any lightningDave

 

[Tom.G]

Hey you nay-sayers, try a Google search for Clear Sky Lightning.

 

[Wrichik Basu]

Has the temperature this year been higher generally?
The are many factors which contribute to formation and intensity of thunderstorms, but higher temperature is a big factor.

It's much more humid than last year, but temperature is a bit less than last year, around 35° at the most.

 

[rootone]

Humidity is also a significant factor.
Thunderstorms hardly ever happen in desert regions no matter how hot it gets.

 

[davenn]

Hey you nay-sayers, try a Google search for Clear Sky Lightning.

Clear sky / clear air lightning still comes from a storm cell
It is just a discharge that leaves the side (usually ) of a cell and comes to ground or dissipates in the air
It can travel for several km or so horizontally from the cell

Being a storm chaser, I am VERY aware of them and the need to keep on the lookout for obvious safety reasons
I have observed a number of clear air strikes over the years but their origin has always been identified

The point is, there is STILL a storm close at hand probably well within 10km from your location
so you are not going to be unaware of an approaching stormDave

 

[Asymptotic]

As soon as the clouds start appearing, lightning bolts reach out to the ground or tall buildings.

Did wind speed pick up just before the lightning began? Was the air dusty before precipitation started?

 

[Wrichik Basu]

Did wind speed pick up just before the lightning began? Was the air dusty before precipitation started?

No to first one. Yes to the second one.

 

[OmCheeto]

Pollution is a increasing problem in almost all metropolitan cities, including Kolkata. Can this sudden increase in lightning strikes be accounted by the pollution? Or is their some other explanation for this rise?

According to the BBC, a very severe lightning storm to your south two months ago was attributed to an unusual weather pattern:

BBC; "...this year cold winds from the Arabian sea collided with warmer winds from northern India and produced conditions that led to the formation of more clouds than usual, Mr Sanku said.
This increased the chance of lightning strikes." ​

I call it severe, as there were 37,000 lightning strikes recorded in 13 hours. That's very roughly 1 strike per second!

In a chart [figure 8] published by the Royal Meteorological Society in 2015 [ref], India gets an average of 120,000 lightning strikes per year.
This means that that one storm accounted for nearly 1/3 of an average year's lighting for the whole country.

 

[davenn]

nice find Om

 

[OmCheeto]

On the other hand, there may be a relation between pollution and lightning:

https://www.telegraphindia.com/calcutta/smell-of-lightning-in-the-air-237394

Anirban Middey of the National Environmental Engineering Research Institute, Nagpur, has shown that an increase in the load of aerosols, or tiny particulate matter (PM), in the atmosphere and clouds of ice crystals and water stimulates lightning discharge.​

Anirban Middey's paper discussing this:

The reciprocal relation between lightning and pollution and their impact over Kolkata, India​

Unfortunately, the paper is behind a paywall, so I can't see how significant the relationship is.
Glossing over the references listed in the paper, it does make a bit of sense.
It's kind of like cloud seeding.
More seeding/pollution makes more clouds.
More clouds make more lightning.
Just a laymanish interpretation, of course.

 

[OmCheeto]

This is interesting. I googled: pollution's effects on cloud formation
and the first hit was an article about a NASA study.
It's actually more complicated, and interesting, than I would have imagined.

Formation of clouds linked to air pollution
by Nasa on 13 July 2006

“When the overall mixture of aerosol particles in pollution absorbs more sunlight, it is more effective at preventing clouds from forming. When pollutant aerosols are lighter in color and absorb less energy, they have the opposite effect and actually help clouds to form,” said Lorraine Remer of NASA’s Goddard Space Flight Center, Greenbelt, Md.​

Here's another article by NASA, published about 20 years earlier:

Atmospheric Aerosols: What Are They, and Why Are They So Important?
Aug. 1, 1996

The sulfate aerosols absorb no sunlight but they reflect it
The sulfate aerosols also enter clouds where they cause the number of cloud droplets to increase but make the droplet sizes smaller.​

Now all we have to do is figure out what kind of pollutants make up the pollution in Kolkata, and how droplet size affects things.

 

[Rive]

Can this sudden increase in lightning strikes be accounted by the pollution? Or is their some other explanation for this rise?

If it is really a sudden increase then it is most likely just some kind of special weather condition. But for example for us in Middle Europe the climate changed so that way back a few decade ago only around half of the rain during summer was from storms, right now it is around 90%. Also thunderstorms starts early, last year we had one in February, but in March it's already nothing uncommon now. In the past the first ones were expected at the end of May.

 

[Asymptotic]

This is interesting. I googled: pollution's effects on cloud formation
and the first hit was an article about a NASA study.

Another NASA article, this one on the effect of Saharan sandstorms on Florida weather.

Not all of the lightning storms that pop up in the American southwest involve precipitation, but rather are generated by dust storms. I'm wondering , could a similar mechanism have played a role in exacerbating this year's storms in India?

 

[davenn]

Another NASA article, this one on the effect of Saharan sandstorms on Florida weather.

good article

Not all of the lightning storms that pop up in the American southwest involve precipitation,

I have never seen one that doesnt

 

[Wrichik Basu]

Not all of the lightning storms that pop up in the American southwest involve precipitation, but rather are generated by dust storms. I'm wondering , could a similar mechanism have played a role in exacerbating this year's storms in India?

Dust storms are common to the central and western India, including our capital New Delhi. In Kolkata, dust storms are started by high velocity winds from a nearby storm carrying water for precipitation. Hence, in most cases, storms are accompanied by rain. But this year, something has happened so as to change the weather abruptly. For the last three days, we are facing extremes of temperatures. Today, it went up to 41°C, highest in this year. The next storm may be dangerous.

 

[jim mcnamara]

@OmCheeto - consider taking that 120K lightning strikes per year in India total as an underestimate, possibly by orders of magnitude.

https://earthobservatory.nasa.gov/IOTD/view.php?id=85600 Cool map!
Also, Kolkata has a monsoon season, with higher levels of lightning, the map averages that out over a year. I'll get to that.

Let's use 10 lightning strikes per year per km² as a conservative interpretation of the map. The surface area of India is: 3,287,259 km²
so:
10 * 3287259 = 32872590, let's use 30 million as a really conservative number, for an India-wide estimate of total lightning events.

From here: https://www.nssl.noaa.gov/education/svrwx101/lightning/types/
Let's use a factor of 5 air to ground events per 10 lightning events:
So our 30 million becomes less, 15 million.

The reason I think this is not a terrible estimate is that one flash can mean a larger number of actual ground strikes, e.g., ~1.45 strikes per flash of cloud to ground per:
https://www.nasa.gov/centers/goddard/news/topstory/2003/0107lightning.html

You will also notice there are significant pinkish areas of >=15 times the lightning events we used above. The very light pink stuff on the map. West Bengal has several pink areas, seen when you click to enlarge the map. Perhaps someone else who is local can do a somewhat better napkin estimate for lightning events per year using the map and getting pink to match geography correctly.
@Wrichik Basu ?

The other factor is seasonality. I cannot quantify that either, but consider that most rain events in West Bengal occur in the rainy season - (monsoon) from June - September. So in June/July you would expect about 3 times as many lightning strikes as in a non-monsoon month. As a guess. There are months with very little rain - January and December: https://weather-and-climate.com/ave...Temperature-Sunshine-fahrenheit,kolkata,India

 

[OmCheeto]

@OmCheeto - consider taking that 120K lightning strikes per year in India total as an underestimate, possibly by orders of magnitude.
...
let's use 30 million as a really conservative number, for an India-wide estimate of total lightning events.
...

Thanks! I was very suspicious of that 120K number.

30,000,000/120,000 = 250

My guess now is that those are daily lightning strikes by year.
Though, it was not obviously presented that way when I reread that section several times.

"Figure 8 demonstrates the annual number of lightning fatalities and lightning flashes in India from 1998 to 2005"​

 

[Wrichik Basu]

Perhaps someone else who is local can do a somewhat better napkin estimate for lightning events per year using the map and getting pink to match geography correctly.
@Wrichik Basu ?

Maybe yes, but I can say that the weather department in Kolkata has no information. Perhaps Earth scientists monitoring the weather will be able give better answers.

 

[MrGamma]

People tend to modify the weather using things such as dry ice and silver halide.

That changes the electrical potential difference from cloud to ground and cloud to space.

You could put up lighting rods to ensure fewer people are effected by a strike, reducing the resistance from Earth to cloud.

You could also invent some type of crazy chem trail product that only increases the electrical potential difference in the upper atmosphere to reduce the strikes towards ground? Could you not? That is more of a question than an answer. Hope that helps.