Answer the following questions.
(i) What is precipitation?
(ii) What is water cycle?
(iii) What are the factors affecting the height of the waves?
(iv) Which factors affect the movement of ocean water?
(v) What are tides and how are they caused?
(vi) What are ocean currents?
ANSWERS
(i) Sun’s heat causes water to evaporate. When the water vapour rises, it begins cooling. The condensing water vapour forms droplets of water. Masses of such water droplets form clouds and float in air. When these droplets become too heavy to float in air, they fall upon land or sea in the form of rain, snow or sleet. This is known as precipitation.
(ii) The water present on the Earth’s surface (on land and in water bodies) gets evaporated by the Sun’s heat. The water vapours rise, condense and form clouds. When the clouds become heavy, the condensed water vapours fall back upon land or sea in the form of rain, snow or sleet. The processes of evaporation, condensation and precipitation continue in a cyclical manner. This way, water continually changes its form and circulates between oceans, atmosphere and land. This continuous circulation of water is known as the water cycle.
(iii) Waves are formed when winds scrape across the ocean surface. Winds blowing at very high speed form huge waves. An earthquake, a volcanic eruption and underwater landslides also affect the height of waves. Such phenomena can shift large amounts of ocean water, thereby causing huge waves to be formed.
(iv) The movements that occur in oceans are broadly categorised as waves, tides and currents.
The factors affecting these movements of ocean water are as follows:
(a) Waves are formed as a result of winds, earthquakes, volcanic eruptions and underwater landslides.
(b) Tides are caused by the strong gravitational pull exerted by the Sun and the Moon on the Earth’s surface.
(c) Another factor affecting the movement of ocean water is temperature. Ocean currents are...