Swell Waves

17.10.2024

Swell Waves

Why in the news?                                                                                                                                                                                                                                      Recently, the Indian National Centre for Ocean Information Services (INCOIS) in Hyderabad, has issued extensive advisories for swell waves for Andaman and Nicobar and Lakshadweep islands as well as parts of coastal areas.

About Swell Waves:

• A swell is the formation of long wavelength waves on the surface of the sea. These are composed of a series of surface gravity waves.
• Swell waves organize themselves into groups of similar heights and periods and then travel long distances without much change.

Formation Of Swell Waves:

• They occur not due to the local winds, but rather due to distant storms like hurricanes, or even long periods of fierce gale winds.
• During such storms, huge energy transfer takes place from the air into the water, leading to the formation of very high waves. Such waves can travel thousands of kilometers from the storm center until they strike shore.

Features of Swell waves:

• Swells have a narrower range of frequencies and directions than locally generated wind waves, because swell waves have dispersed from their generation area, have dissipated and therefore lost an amount of randomness, taking on a more defined shape and direction.
• These waves can propagate in directions that differ from the direction of the wind, in contrast to a wind sea.
• Their wavelengths may rarely exceed more than 150 m. Swell wavelength, also, varies from event to event. Occasionally, swells which are longer than 700 m occur as a result of the most severe storms.
• It occurs without precursors or any kind of local wind activity and as a result.
• In India early warning systems like the Swell Surge Forecast System launched by the Indian National Centre for Ocean Information Services (INCOIS) in 2020 give forewarning seven days in advance.

                                                                 Source: The Hindu

Consider the following statements regarding Swell wave:

Statement-I:It is the formation of long wavelength waves on the surface of the seas.

Statement-II: It is formed due to the presence of the local winds.

Which one of the following is correct in respect of the above statements?

A.Both Statement-I and Statement-II are correct, and Statement-II is the correct explanation for Statement-I.

B.Both Statement-I and Statement-II are correct, and Statement-II is not the correct explanation for Statement-I.

C.Statement-I is correct, but Statement-II is incorrect.

D.Statement-I is incorrect, but Statement-II is correct.

Answer C