Heavy rainfall is expected in Andhra Pradesh, Telangana and Odisha due to cyclonic storm 'Roanu', which will intensify into a "severe cyclonic storm"  according to the India Meteorological Department.

The cyclone will make a landfall in Bangladesh on the intervening night of May 21 and 22 "heavy to very heavy rainfall" is expected in Andhra Pradesh, Telangana and Odisha.

What is a tropical cyclone?

A tropical cyclone is an intense low pressure area or a whirl in the atmosphere over tropical or sub-tropical waters, with thunderstorm activity and winds at low levels, circulating either anti-clockwise (in northern hemisphere) or clockwise (in southern hemisphere). From the centre of a cyclonic storm, pressure increases outwards. 

How do they form?

Warm, moist air derived from tropical oceans with surface temperature near of 27 degrees Celsius or above. Winds blows from different directions and converge, causing hot air to rise and form storm clouds.

Winds with no big variation in height (low wind shear) allows the storm clouds to rise vertically to high levels. With the spin induced by the earth's rotation, clusters of storm clouds rotate, resulting in a tropical depression and If it continues, the depression becomes a tropical storm, cyclone or super cyclone depending on its intensity.

Why cyclones are named?

Cyclones are named to provide ease of communication between weather scientists and people. As tropical belt is prone to cyclones, names prevent the confusion.

Do all cyclones have names?

The usual practice for a storm to be named when it reaches tropical storm strength (winds speed of 62 kmph)

How cyclones are named?

Within the North Indian Ocean, tropical cyclones are named by the India Meteorological Department (IMD/RSMC New Delhi).

There are eight lists of names submitted by eight countries and they are used in sequence.

The names of cyclones in Indian seas are not allocated in alphabetical order, but are arranged by the name of the country which contributed the name.