Scientific reasons for deadly cloudbursts in Pakistan and India have emerged
Humidity, monsoon and mountains are the three main factors for cloudbursts.

Deadly cloudbursts have been wreaking havoc in the mountainous regions of India and Pakistan. Large, sudden floods have claimed lives in both countries.

These extreme weather events involve dropping heavy rains on a limited area in a short period of time.

A single cloudburst in Pakistan’s northwestern Buner district killed nearly 300 people. The torrential rains caused flash floods, landslides and flowing streams.

Large rocks crashed down slopes, crushing houses and reducing entire villages to rubble.

In one of the deadliest incidents, 24 members of a family in Qadirnagar village died when floodwaters entered their house the day before a wedding.

The head of the family, Umar Khan, said they survived because they were out of the house at the time. He added that four of his relatives were still missing.

Neighbouring India was also badly hit, with a cloudburst in the northern state of Uttarakhand earlier this month. Local TV footage showed how floodwaters rushed down the mountain and engulfed the Himalayan village of Dharali.

This follows a devastating cloudburst in the same state in 2013, which killed more than 6,000 people and affected 4,500 villages.

What is a cloudburst?

A cloudburst occurs when a large amount of rain falls in a very short period of time, usually more than 100 mm (about four inches) of rain in an hour over a limited area, about 30 square kilometers (11.6 square miles).

Cloudbursts are sudden and intense events that can have devastating effects and cause widespread damage. They can last for several hours or more, similar to normal rainfall. In this event, the cloud bursts and drops its entire load at once, as if a rain bomb had exploded.

Several factors contribute to cloudbursts, including the rising of warm, moist air, high humidity, low pressure, instability, and the formation of convective clouds.

When moist air hits a mountain or ridge, it is forced to rise. This rising air cools and condenses. This creates large, dense, and heavy clouds capable of producing heavy rain.

Mountains or hills act as barriers and often force these clouds to become confined in one place, preventing them from breaking up or moving easily.

The powerful updrafts keep moisture suspended within the clouds and delay rainfall. When the clouds can no longer hold the accumulated moisture, they burst and release all the water in one go.

Why do cloudbursts occur in India and Pakistan?

Moisture, monsoon and mountains are the three main factors for cloudbursts. All three are present in the regions of India and Pakistan, making these regions very vulnerable to such severe weather events.