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

Why is the earth called the "Blue Planet"?

Because about 91 per cent of the planet's water is found in the oceans, giving it an abundant water surface.

What is the hydrological cycle?

The continuous circulation of water among the oceans, atmosphere, land surface, subsurface and organisms.

Name the four major divisions of the ocean floor.

The continental shelf, the continental slope, the deep-sea plain and the oceanic deeps (trenches).

Why are continental shelves economically important?

Their massive sedimentary deposits, accumulated over a long time, become a source of fossil fuels.

A flat-topped seamount that shows evidence of gradual subsidence to become a submerged flat-topped mountain.

What is the thermocline?

The boundary zone in the ocean (usually 100–400 m down) where temperature decreases rapidly with depth.

How does ocean temperature change with latitude and depth?

It decreases from the equator towards the poles (about 0.5°C per degree of latitude) and decreases with increasing depth.

What is salinity and how is it expressed?

The total dissolved salts in sea water, expressed as parts per thousand (‰); the open ocean averages about 35‰.

Name three factors affecting ocean salinity.

Evaporation and precipitation, fresh-water inflow from rivers (and freezing/thawing of ice), wind and ocean currents.

What is the halocline?

The zone in the ocean where salinity increases sharply with depth.

Water (Oceans)

Class 11 Geography · Fundamentals of Physical Geography · Chapter 12

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Summary

Water is a cyclic resource; about 91 per cent of the planet's water is in the oceans, which is why the earth is called the "Blue Planet". The hydrological cycle is the continuous circulation of water among the oceans, atmosphere, land and organisms through evaporation, transpiration, condensation and precipitation. The ocean floor is divided into four major divisions: the continental shelf (the shallow extended margin, average width about 80 km, a source of fossil fuels), the continental slope (which marks the end of the continents), the deep-sea plain (the flattest, smoothest region) and the oceanic deeps or trenches (the deepest parts). Minor relief features include mid-oceanic ridges, seamounts, submarine canyons, guyots (flat-topped seamounts) and atolls. Ocean temperature decreases from the equator to the poles and with depth; the thermocline is the boundary zone of rapid temperature decrease, and the temperature structure has three layers. Salinity, the total dissolved salts (expressed as parts per thousand), averages about 35‰ in the open ocean and is affected by evaporation, precipitation, river inflow, freezing and currents; it changes with depth at the halocline, where salinity increases sharply.

Water (Oceans)

Key terms

Hydrological cycle

the continuous circulation of water among oceans, atmosphere, land and organisms.

Continental shelf

the shallow, extended margin of a continent, average width about 80 km, a source of fossil fuels.

Deep-sea plain

the flattest, smoothest region of the ocean floor (3,000–6,000 m deep).

Guyot

a flat-topped seamount that shows evidence of gradual subsidence.

Thermocline

the boundary zone in the ocean where temperature decreases rapidly with depth.

Salinity

the total dissolved salts in sea water, expressed as parts per thousand (about 35‰ in the open ocean).

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About what proportion of the planet's water is found in the oceans?

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Water (Oceans)

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Practice quiz · Water (Oceans)

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