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SAI INTERNATIONAL SCHOOL
                         STD VII                                                SUBJECT - GEOGRAPHY
               TOPIC-CH – 5- WATER(LESSON NOTES)

               Sub-topic- TIDES

               NOTES- Level of the ocean water goes up and down each day, and we call these tides.
               High tide is when the water level is highest, and low tide is when the water level is lowest.
               Ocean tides are mainly caused by the gravitational pull of the moon and the Sun. The moon's
               gravity pulls the ocean toward it during high high tides. During low high tides, the Earth itself
               is pulled slightly toward the moon.

               High Tide/ Spring Tide-The highest tides, called spring tides, are formed when the earth, sun
               and moon are lined up in a row. This happens every two weeks during a new moon or full
               moon.

               Small Tide/ Neap tide-Smaller tides, called neap tides, are formed when the earth, sun and
               moon form a right angle. This causes the sun and moon to pull the water in two different
               directions. Neap tides happen during a quarter or three-quarter moon.

               How are tides helpful or human:


                   1. Fishing: As many fishes come near to the shore with high, it helps in fishing.
                   2. Tidal Zone Foods: Edible sea creatures like Crabs, mussels, snails, seaweed etc.also
                       come near to the shore.
                   3. Navigation: High tides help in navigation. They raise the water level close to the
                       shores which helps the ships to arrive at the harbour more easily.
                   4. Tidal Energy: Hydro electricity is generated.
                   5. Keeps the mouth of the river clean.


               Draw the diagram in the notebook-
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