Why were India's dust storms so deadly? By Navin Singh Khadka

Environment correspondent, BBC World Service Published duration 4 May 2018

media caption The storms destroyed homes and uprooted trees

Indian officials say the main reason the most recent dust storms were so catastrophic was because of the time when the strongest winds hit - at night, as people were sleeping indoors.

Most of 125 reported deaths were because of the collapse of buildings and other structures.

But meteorologists also point out how the devastating winds blew.

They say it was an intense downward movement of air, known as downburst.

image copyright AFP image caption Dust storms later became thunderstorms with lashing rains

That vertical - and not horizontal - movement of the wind, they say, had damaging impacts on structures resulting in so many deaths.

The storms followed very high temperatures in the region.

Just across the border in Pakistan, local media reported 50.2C (122.3F) in the town of Nawabshah - a record for April.

Scientists say high temperatures played a significant role in intensifying the storms that originated in the desert area of north-west India and further west.

But they did not remain only dust storms.

image copyright Getty Images image caption High-speed winds and lightning devastated many villages

By the time they had reached states such as Punjab, Uttar Pradesh and further east, they also became thunderstorms with lashing rains.

Meteorologists say easterly winds from the Bay of Bengal brought in moisture that merged with the destructive winds from the west.

Scientists say high temperatures, moisture and an agitated atmosphere make a perfect combination for storms of this type.

The damage has been the worst seen in 20 years, according to officials with India's Met department.

media caption India dust storms

They have also issued warnings that more bad weather is to come, with severe thunderstorms expected in several places in northern India over the next few says.

The extraordinary dust and thunderstorms have come just when concerns have been mounting about the rapid rate of desertification in several Indian states.

The environment ministry says a quarter of the country's land is undergoing desertification - while independent experts put the figure much higher.

Increasing desertification would mean more intense and damaging dust storms.

Climate scientists have predicted that droughts will become more severe in this part of South Asia with climatic changes.

And because of that, dust storms like the most recent ones, could occur more frequently.