Why is it in the News?

As a result of the low-pressure area formed over the Atlantic Ocean moving into the Indian Ocean, high swell waves in the range of 11 m were formed.

What Are Swell Waves?

• Swell waves are characterized by the formation of long wavelength waves on the surface of the seas, propagating along the interface between water and air.
• They are commonly known as surface gravity waves due to their nature.

Origin:

• Unlike waves generated by immediate local winds, swell waves originate from distant weather systems.
• These waves are the result of prolonged wind action over a significant area of water, known as fetch.
• Even after the wind subsides or shifts, or the waves move away from the wind source, swell waves persist and continue to propagate.

Influencing Factors:

• The speed of the wind, the extent of ocean surface area affected by consistent wind direction (fetch), and the duration of time the winds persist over the same part of the ocean are all contributing factors to the formation and behavior of swell waves.

Characteristics of Swell Waves:

• Limited Frequency and Direction Range: Swell waves exhibit a narrower range of frequencies and directions compared to wind-generated waves occurring locally.
• Defined Shape and Direction: Swell waves assume a more distinct shape and direction, displaying less randomness than waves generated by local winds.
• Directional Orientation: Unlike wind waves, swell waves are characterized by the direction from which they originate rather than where they are headed.
• Wavelength Variation: Swell waves typically possess long wavelengths, although this can vary depending on the size of the water body.
  • Generally, their wavelengths seldom exceed 150 meters.
  • However, on occasion, particularly severe storms may produce swells with wavelengths surpassing 700 meters.

What are the Differences Between a Normal Wave and Swell Waves?

Normal Waves:

• Random Nature: Normal waves encompass any spontaneous disturbance occurring in the sea, exhibiting a wide array of forms, types, shapes, heights, periods, directions, and speeds.
• Varied Characteristics: Waves can manifest in diverse forms and attributes, subject to the prevailing conditions in the ocean.

Swell Waves:

• Deep-water Linear Waves: Swell waves are a distinct category of deep-water, linear waves originating or emerging from a chaotic wave system during external weather events due to wave dispersion.
• Defined Characteristics: Swells travel in a specific direction as uniform, high-speed, long waves that maintain consistency over time, with speeds determined by their wavelengths and periods.
• Extensive Travel: Swell waves traverse significantly greater distances compared to typical wave packets, exhibiting remarkable endurance.
• Independence from Local Weather: Swell waves remain unaffected by local weather systems, retaining their characteristics even in the presence of nearby weather phenomena.