A cloudburst triggered multiple landslides and caused flooding in Itanagar.

The NH-415, crucial for the state capital's connectivity, experienced flood-like conditions, stranding numerous vehicles.

Heavy rains inundated homes near Energy Park and Bank Tinali areas. 

What is cloudburst?

• A cloudburst is a localised but intense rainfall event.

• Short periods of extremely heavy rain over a small geographical area can lead to widespread destruction.

• Not all instances of very heavy rainfall qualify as cloudbursts. A cloudburst has a specific definition:

Rainfall measuring 10 cm or more in an hour over an area of approximately 10 km x 10 km is considered a cloudburst.

• By this definition, 5 cm of rainfall in a half-hour period over the same area would also be classified as a cloudburst.

Occurrence:

• High relative humidity, maximum cloud cover, low temperatures, and slow winds can lead to rapid condensation of clouds, resulting in a cloudburst.

• As temperatures rise, the atmosphere holds more moisture, which can lead to short, intense rainfall lasting from half an hour to an hour, causing flash floods in mountainous regions and urban floods in cities.

Cloudbursts vs Rainfall:

• Rain is condensed water falling from a cloud, whereas a cloudburst is a sudden, heavy rainstorm.

• Rainfall exceeding 10cm per hour is classified as a cloudburst.

• Cloudbursts occur naturally, unexpectedly, abruptly, and with intense downpours.

Impact of Climate Change:

• Studies indicate that climate change will increase the frequency and intensity of cloudbursts globally.

• In May 2021, the World Meteorological Organisation reported a 40 per cent chance that the annual average global temperature will temporarily reach 1.5°C above pre-industrial levels within the next five years.

• There is a 90 per cent likelihood that at least one year between 2021 and 2025 will become the warmest on record, surpassing 2016.

• The Himalayan region is experiencing more cloudbursts due to its higher rate of temperature rise compared to the global average.

Consequences of cloudbursts:

• Flash floods

• Landslides

• Mudflows

• Land caving

Prediction:

• There is no reliable technique for predicting cloudbursts due to their rapid development.

• Detecting the likelihood of a cloudburst requires a fine network of radars, which is costly.

• Identifying areas prone to heavy rainfall and the meteorological conditions that favor cloudbursts can help mitigate damage.

(The author is a trainer for Civil Services aspirants.)