What are Cloudbursts?
Source: Hindustan Times
GS III: Disaster and disaster management
Overview
- News in Brief
- What are Cloudbursts?
- Cloudburst Events in India
Why in the News?
Over 20 people have been killed in destruction caused by cloudbursts and flash floods in different parts of Himachal Pradesh and Uttarakhand over the last three days.
News in Brief
- Isolated areas in these two states have reported heavy rainfall during this time.
- It triggering landslides and flash floods that have disrupted rail and road traffic, and resulted in house and wall collapses.
- In Uttarkashi Dharali Village Cloudburst reportedly damaging some buildings, hotels, and shops.
What are Cloudbursts?
- A cloudburst is a localised but intense rainfall activity.
- Short spells of very heavy rainfall over a small geographical area can cause widespread destruction, especially in hilly regions where this phenomenon is the most common.
- Not all instances of very heavy rainfall, however, are cloudbursts.
- Definition
- Rainfall of 10 cm or more in an hour over a roughly 10 km x 10-km area is classified as a cloudburst event.
- By this definition, 5 cm of rainfall in a half- hour period over the same area would also be categorized as a cloudburst.
Comparison with rainfall in India
- India receives about 116 cm of rainfall over the entire year.
- If the entire rainfall everywhere in India during a year were spread evenly over its area, the total accumulated water would be 116 cm high.
- There are huge geographical variations in rainfall within the country, and some areas receive over 10 times more than that amount in a year.
- But on average, any place in India can be expected to receive about 116 cm of rain in a year.
- During a cloudburst a place receives about 10% of its annual rainfall within an hour.
Cloudburst Events in India
- All the events can’t be described as cloudburst.
- Cloudburst happens only in a small area.
- Most of these happen in the Himalayan states, where the local topology, wind systems, and temperature gradients between the lower and upper atmosphere facilitate the occurrence of such events.
- Most of the times, cloudbursts can’t be measured as this rainfall happens in localised areas where we lack og measuring instruments.
Increasing frequency of Cloudbursts
- Incidents of extreme rainfall, as also other extreme weather events, are increasing.
- As a result of climate change the events of cloudbursts may also incraese.
India Meteorological Department forecasts
- The weather forecast of IMD is well advanced, still it can’t predict the amount of rainfall.
- Scientists do not have the capability to predict exactly how much rain is likely to fall at any given place.
- Forecast is not possible to predict the situation of localised areas.
- The predictions that can be expected are warnings for heavy to very heavy rainfall events, and these are routinely forecast four to five days in advance.
India Meteorological Department
- India Meteorological Department was established in 1875.
- It is the National Meteorological Service of the country and the principal government agency in all matters relating to meteorology and allied subjects.
- The Director General of Meteorology is the Head of the India Meteorological Department, with headquarters at New Delhi.
- For the convenience of administrative and technical control, there are 6 Regional Meteorological Centres at Mumbai, Chennai, New Delhi, Calcutta, Nagpur and Guwahati.
- IMD is under the Ministry of Earth Sciences (MoES).
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