# RBSE Class 11 Geography Notes Chapter 17 Hydrological Cycle and Distribution of Water Bodies

Go through these RBSE Class 11 Geography Notes Chapter 17 Hydrological Cycle and Distribution of Water Bodies contain important concepts so that students can score better marks in the exam.

## Rajasthan Board RBSE Class 11 Geography Notes Chapter 17 Hydrological Cycle and Distribution of Water Bodies

Hydrological Cycle

• In the hydrological cycle, the movement of water and its conversion into gaseous, liquid and solid states is included.
• Storage and flow of underground water, evaporation and humidity are included.
• Regular cyclic arrangement of water in the hydrosphere, atmosphere and lithosphere is included in the hydrological cycle.
• Water reaches the atmosphere in form of water vapour through evaporation and transpiration from the sea, lakes, rivers, terrestrial part and plants, etc. and under seasonal conditions, this water vapour forms clouds through condensation and it again reaches the hydrosphere and lithosphere in the form of rainfall.
• Cyclic stages of water occurring in different forms are included in the hydrological cycle.
• Only 1% of the water available on earth is transmitted in the hydrological cycle every year. Large part of the water involved in hydrological cycle is pure water.
• Water is stored in the oceans, ice caps and rocks for a long time, while it remains for the short time in the rivers and the atmosphere.

Mechanism of Hydrological Cycle

• Conversion of water into vapour and its accumulation in the atmosphere is an extremely important process on which the change of climate is dependent.
• Due to the energy received from the sun, water of the oceans enters the atmosphere in the form of vapour.
• Water vapour condenses and causes rainfall on the earth’s surface.
• In the major stages of hydrological cycle, evaporation and transpiration, precipitation and air circulation are included.
• In nature, hydrological cycle is the basis of climate, and life of the humans, vegetation, climate and all other living beings.

Water Bodies

• Area of the entire earth is 50.995 million sq. km. out of which the hydrosphere is extended on 36.106 million sq. km. area and the lithosphere is extended on 14.889 million sq. km. area.
• According to new exploration, land is found on 29.2% part and water on 70.8% part of the earth’s surface.
• Water and land parts are located opposite to each other on the earth’s surface. Examples: land part of Africa is located opposite to the Pacific Ocean, land part of America is located opposite to the Indian Ocean.
• The shape of the continents and oceans is almost triangular. The base of the oceans is in the southern hemisphere and the apex is in the north.
• Under the water bodies of the world, in addition to the vast oceans, inland seas like Mediterranean Sea, Red Sea, bays and lakes are also included.
• As the study of airmass has an important place in climatology, in the same way, water bodies have a special place in oceanography.
• In the factors affecting the structure of water bodies, the latitudinal distance, rainfall, snowfall, direction of sustainable winds, sinking or divergence of water, sea currents and oceanic vartex are included.

Distribution of Water Bodies

• Distribution of water bodies is based on the temperature and salinity of water.
• In the oceanic water bodies, Antarctica Coastal water body, North Atlantic Coastal water body, Antarctica Intermediate water body, North Pacific Intermediate water body, Central water body and Equatorial water body are included.
• Antarctica Coastal water body is found in the south of the Indian Ocean, and the Atlantic Ocean near the Antarctica continent. The salinity of water is 34.62% in this part.
• North Atlantic Coastal water body is found between Labrador Sea and Iceland and Southern Greenland.
• Antarctica Intermediate water body is found all around the Antarctica continent.
• North Pacific Intermediate water body has originated towards the north-east near 40 degrees northern latitude in the Pacific Ocean.
• Central water bodies are found between 35 degrees to 42 degree northern and southern latitudes in the regions of winter sub-tropical convergence.
• Equatorial water bodies are located along the equatorial line in the Pacific Ocean and the Indian Ocean.

### Hydrological Cycle and Distribution of Water Bodies Notes Important Terms

→ Water Cycle or Hydrological Cycle: The cycle of processes by which water circulates between the earth’s oceans, atmosphere and land, involving precipitation as rain and snow, drainage in streams and rivers, and return to the atmosphere by evaporation and transpiration.

→ Condensation: The process by which a substance changes from vapour into liquid state.

→ Precipitation: Rainfall on the earth’s surface in any form of water from atmospheric sources. It is deposited on the surface in the forms of dew, rainfall, hailstone, snow, sleet, etc.

→ Air Circulation: Movement of wind from one place to another place.

→ Transpiration: A physical process by which the moisture absorbed by the plants through their roots is returned to the atmosphere in the form of water vapour through minute pores on their leaves.

→ Surface Water: The stable water flowing on the upper part of the earth’s surface which is found in rivers, canals, open and internal seas and lakes.

→ Gulf or Bay: A deep inlet of the sea almost surrounded by land with a narrow mouth or a very large area of sea surrounded on three sides by a coast.

→ Climatology: The science under which the study of climatic elements, their origin and organisation, their effects and relations with natural environment is included.

→ Airmass: Airmass is that vast area of the atmosphere in which similarity is found in the climatic conditions : temperature and humidity in the horizontal plane on different heights.

→ Oceanography: The science under which the study of nature of water of the oceans, their depth, temperature and movement, vegetation and creatures in the oceans is included.

→ Mid Latitudes: Latitudes located between Tropic of Cancer Circle and Arctic Circle (23$$\frac{1}{2}$$ degree to 66$$\frac{1}{2}$$ degree North Latitude), and Tropic of Capricorn Circle and Antarctic Circle (23$$\frac{1}{2}$$ degree to 66 degree South Latitude).

→ Low Latitude: Latitude located between Tropic of Cancer Circle and Tropic of Capricorn Circle (between 23$$\frac{1}{2}$$ degree north to 23$$\frac{1}{2}^{\circ}$$ south latitudes).

→ Salinity: The amount of salt dissolved in the water of a reservoir (ocean, sea, lake, river) which is usually expressed as per thousandth part of the total water.

→ Westerlies or West Winds: Regular winds blowing from the sub-tropical high atmospheric pressure belt towards the sub-polar low atmospheric pressure belt in both the northern and southern, hemispheres.

→ Sub-Tropical Zone: The zone located between the tropical zone and the temperate zone (23$$\frac{1}{2}^{\circ}$$ degree to 40 degree North and South latitudes) is called the Sub-Tropical.