Page 101 - Journeys Through Society-7

shape and rotates eastwards. This makes water and of moisture, which they shed as they blow across. Why
winds deflect to the right in the northern hemisphere do you think the temperature of winds must drop to
and to the left in the southern hemisphere. This is shed moisture?
known as the Coriolis Effect. Cold ocean currents are dense and flow below the
surface of oceans. They reduce the air temperature of
the places they flow close to. Coastal deserts form in
this manner, the Atacama Desert in South America is
one such example.
Places where warm and cold currents meet create
ideal conditions for fish to breed in huge populations,
thereby causing valuable fishing grounds to develop.

Tides

Ocean currents The periodic rise and fall of the sea level, usually twice
a day, in a particular place is known as a tide. Tides are
There are certain factors that cause and influence the caused by the gravitational pull of the Moon and the
direction of ocean currents. They are as follows: Sun, and the Earth's rotation. When the gravity of the
• Difference in temperature Moon pulls the Earth at a particular location, a high
• Difference in salinity tide occurs. When it releases its pull, the water level
• Earth’s rotation comes down and a low tide occurs.

• Planetary winds
• Shapes of coastlines

AI Fact Technology Literacy

It shows how significant AI can be, by creating new tools
that can produce a much more detailed and precise view
of the plastic pollution problem in rivers that drain into
the world’s oceans.
Formation of Tides
Warm and Cold Ocean Currents
Exceptionally high tides are caused during the full
Ocean currents that move from the Equator to the moon and new moon days. Such tides are called
poles are warm ocean currents, for example, the Gulf 'spring tides'. On the other hand, when the Moon is in
Stream which washes the shores of the Gulf of
its first and last quarter, exceptionally low tides occur.
Mexico. Ocean currents that move from the poles to These are called 'neap tides'.
the Equator are cold ocean currents, for example, the
cold Peruvian current which washes the western Importance of Tides
shores of South America. Tides have great commercial importance especially
Warm ocean currents are light and flow along the for the fishing and shipping industries. Heavy
surface of oceans. They move about 40 per cent of the freighters can enter shallow ports only at high tide,
heat from the Equator to the poles. They modify the when the water is deepest. Fishing boats are also
temperature of the places they flow close to. When subject to the rise and fall of tidal waters. Tidal energy,
winds blow across warm currents, their temperature which can be harnessed during a high tide, is an eco-
increases. This enables them to absorb huge amounts friendly source of energy which never gets exhausted.

94