As Cyclone Arnab approaches, a look at the science behind naming of cyclones

Cyclones are often identified by names such as Arnab, Amphan, Fani and Biparjoy, but have you ever wondered who chooses these names and why? The process is not random. Tropical cyclones are named according to systems established by meteorological organisations, with rules that vary across different ocean basins.

Naming a cyclone makes it easier for weather agencies, governments, the media and the public to identify a storm and communicate warnings. It also helps avoid confusion when multiple weather systems are active at the same time. However, not every tropical disturbance receives a name. A system must meet the relevant meteorological criteria before it can be named.

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How are cyclones named around the world?

According to the World Meteorological Organization (WMO), cyclone names are selected through regional arrangements involving national meteorological services. Countries in a particular region submit names that are compiled into lists and used when tropical cyclones develop. The exact process differs from one region to another, as there is no single worldwide list for all cyclones.

The names are generally selected in advance rather than chosen after a storm develops. They are expected to be short, easy to pronounce, appropriate across the countries in the region and distinguishable from other names in use. This helps people recognise a storm quickly, particularly when official warnings are being issued.

The terminology also depends on where the storm forms. These weather systems are broadly the same type of tropical system, but they are commonly called hurricanes in the Atlantic and northeastern Pacific, typhoons in the northwestern Pacific, and cyclones in the Indian Ocean and South Pacific.

The practice of naming storms has evolved over time. The US National Oceanic and Atmospheric Administration (NOAA) explains that meteorologists began using names to identify tropical storms more systematically during the 20th century. In the Atlantic, the United States began using women's names for storms in 1953. Male names were subsequently introduced into naming systems in the eastern North Pacific in 1978 and the Atlantic in 1979.

Today, the Atlantic uses six rotating lists of names, with each list returning every six years. However, a name may be retired if a storm is particularly deadly or destructive. Retiring a name prevents it from being reused in that region because of the devastation or loss of life associated with the storm.

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How are cyclones named in India?

India follows a regional naming system for tropical cyclones developing over the North Indian Ocean, which includes the Bay of Bengal and the Arabian Sea. The India Meteorological Department (IMD), through its Regional Specialised Meteorological Centre in New Delhi, is responsible for naming these systems.

According to the Ministry of Earth Sciences, Government of India, the naming system involves 13 countries: Bangladesh, India, Iran, the Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, the United Arab Emirates and Yemen.

The list introduced in 2020 contains 169 names, with each of the 13 countries contributing 13 names. These names are arranged in a list and used sequentially. The system allows participating countries to contribute names instead of leaving the naming process to a single country.

A cyclone is assigned a name when its maximum sustained surface wind speed reaches 34 knots, or approximately 62 kilometres per hour. This means a weather system is not named merely because it develops over the sea or is forecast to bring rain. It must first meet the prescribed wind-speed threshold.

The names are used in sequence from the regional list. A storm is not named according to which country it is expected to affect, and the name does not indicate where it will make landfall. A name contributed by one country can be assigned to a cyclone that eventually affects another country.

Unlike the Atlantic system, in which names of particularly destructive storms may be retired and replaced, the North Indian Ocean system does not reuse a name once it has been used. This is why the region has a large list of names contributed by all participating countries.

Also Read: Cyclone likely to form over Bay of Bengal in few days, rain alert for Andhra Pradesh, Odisha: IMD

Does a cyclone's name tell us how dangerous it is?

No. A cyclone's name is an identification tool, not a measure of its strength. The severity of a storm depends on factors such as wind speed, rainfall, storm surge, its movement and the vulnerability of the areas in its path.

A name makes it easier for officials and the public to follow updates about a particular system, but people should rely on official forecasts and warnings to understand the risks. The naming system is ultimately designed to make communication clearer and help people respond to a developing storm.