Fetch
Topic: Movements of Ocean Water: Waves, Tides and Currents · NCERT: Class 11, Ch 13 "Movements of Ocean Water"
Meaning
Fetch is the stretch of open water that the wind blows over in one direction without a break. The longer the fetch, the more time and distance the wind has to pass its energy into the water. Wave height depends on three things together: how strong the wind is, how long it blows, and the fetch. A small lake or a sheltered bay has a short fetch, so its waves stay small. A wide, open ocean has a long fetch, so its waves can grow very large.
Example
The Southern Ocean around Antarctica has strong westerly winds blowing over thousands of kilometres of water with no land in the way. This huge fetch raises some of the biggest waves on Earth.
Don't confuse with
- Wave height: the result (the distance from trough to crest). Fetch is one of the causes that decides how high the waves can grow.
Related concepts
- Wave
- Orbital motion of water particles
- Wave height
- Wavelength
- Swell
- Breaking of waves
- Longshore drift
- Kallakkadal