What went wrong when the king rode under the arch?

It was too low and knocked off his crown

How does the chain of blame unfold in the poem?

Each accused person blames another, ending with the king's own changes

What are waves and where do they get their energy?

Waves are the movement of energy (not water) across the ocean surface; they get their energy from the wind.

When does a wave break?

When the depth of water becomes less than half the wavelength of the wave.

What are tides and what causes them?

The periodical rise and fall of the sea level, caused mainly by the gravitational pull of the moon and the sun together with the centrifugal force.

Distinguish spring tides from neap tides.

Spring tides are higher and occur when the sun, moon and earth are aligned (full and new moon); neap tides are lower and occur when the sun and moon are at right angles.

Name the three frequency-based types of tides.

Semi-diurnal, diurnal and mixed tides.

Why are tides important for human activity?

They aid navigation and fishing, help desilt sediments and remove pollution from estuaries, and are used to generate tidal power.

What are ocean currents?

Continuous flows of a large mass of ocean water in a definite path and direction.

Name the primary forces that influence ocean currents.

Solar heating, wind, gravity and the Coriolis force.

How are ocean currents classified by temperature?

Into warm currents (carrying warm water to cold areas) and cold currents (carrying cold water to warm areas).

Where are the world's best fishing grounds and why?

In the mixing zones of warm and cold currents, where mixing replenishes oxygen and favours the growth of plankton, the primary food for fish.

Movements of Ocean Water

Class 11 Geography · Fundamentals of Physical Geography · Chapter 13

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Summary

Ocean water is dynamic, moving horizontally as waves and currents and vertically as tides. Waves are energy, not water, moving across the surface; water particles travel in small circles while the wave train moves ahead, and waves break when the depth is less than half the wavelength. Waves get their energy from the wind, and their size depends on wind strength, duration and fetch. Tides are the periodical rise and fall of the sea level, mainly due to the gravitational attraction of the moon and, to a lesser extent, the sun, together with the centrifugal force, which create two tidal bulges. Tides are classified by frequency (semi-diurnal, diurnal, mixed) and by the sun-moon-earth positions: spring tides (higher, when sun, moon and earth are aligned, at full and new moon) and neap tides (lower, when sun and moon are at right angles). Tides aid navigation, fishing, desilting and tidal power generation. Ocean currents are continuous flows of water in a definite direction, driven by primary forces (solar heating, wind, gravity, the Coriolis force) and secondary forces (density differences). They are classified by depth (surface and deep-water) and by temperature (warm and cold). Currents influence climate, fog and the world's best fishing grounds where warm and cold currents mix.

Movements of Ocean Water

Key terms

Wave

the movement of energy across the ocean surface, where water particles travel in small circles.

Tide

the periodical rise and fall of the sea level, mainly due to the gravitational pull of the moon and sun.

Spring tide

a higher-than-normal tide when the sun, moon and earth are in a straight line (full and new moon).

Neap tide

a lower-than-normal tide when the sun and moon are at right angles to the earth.

Ocean current

a continuous flow of a large mass of water in a definite direction.

Gyre

a large circular system of ocean currents produced by the Coriolis force in the ocean basins.

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Waves are essentially the movement of which across the ocean surface?

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Movements of Ocean Water

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Summary

Key terms

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Practice quiz · Movements of Ocean Water

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