Water Class 7 Social science ( Geography ) NCERT Solution CBSE

Water
Class 7
Social science ( Geography )
NCERT Solution
CBSE

1. WATER Rivers, the waterfalls, raindrops, water in your taps. Childrens love to float paper boats in rain puddles. A liquid amount of water, especially the water in a lake river or sea.

2. The sun’s heat causes evaporation of water into vapour . When the water vapour cools down, it condenses and forms clouds. From there it may fall on the land or sea in the form of rain, snow or sleet.

3. Water cycle

4. The process by which water continually changes its form and circulates between oceans, atmosphere and land is known as the water cycle.

5. The major sources of fresh water are the rivers, ponds, springs and glaciers. The ocean bodies and the seas contain salty water. The water of the oceans is salty or saline as it contains large amount of dissolved salts. Most of the salt is sodium chloride or the common table salt that you eat.

6. WORLD- MAJOR SEAS, LAKES AND RIVERS

7. Distribution of Water Bodies The distribution of water in percentage: oceans : 97.3 Ice- caps : 02.0 Ground water : 0.68 Fresh water Lakes : 0.009 Inland seas and salt lakes : 0.009 Atmosphere : 0.0019 Rivers : 0.0001 100.00

8. Ocean Circulation Ocean Circulation is the large scale movement of water in the ocean basins.

9. The water of the oceans is not calm like that of ponds or lakes or other such bodies. It is always in a state of movement. It circulates in various directions, following different patterns under different forces. These movement are categorized as waves, current, and tides. It is a key regulator of climate by storing and transporting heat, carbon, nutrients and fresh water all around the world. The wet sand on the beach, the cool breeze, the sea bird, the smell of the salt in the air and music of the waves; everything is so fascinating.

10. W AVES

11. When the water on the surface of the ocean rises and falls alternate they are called waves. Waves travel at a speed of more than 700 km per hour. Waves are generally caused by the action of winds on the surface of ocean water.

12. TIDES

13. The rhythmic rise and fall of ocean water twice in a day is called a tides. It is high tide when water covers much of the shore by rising to its highest level. It is low tide when water falls to its lowest level and recedes from the shore. The strong gravitational pull exerted by a sun and the moon on the earth’s surface causes the tides. Tides are very long-period waves that move through the ocean in response to the forces exerted by the moon and the sun.

14. OCEAN CURRENTS Ocean Currents are streams of water flowing constantly on the ocean surface in definite direction. The ocean current may be warm or cold. The Labrador ocean current is cold current while the gulf stream is a warm current. The areas were the warm and the cold currents meets provide the best fishing grounds and also experience foggy weather of the world. Seas around Japan and the Easthern coast of North America are such example.