Science Answer The Following Questions In Short.[2 Marks Each]

The water cycle is important for us because of the following reasons:

• Water cycle helps in regulating weather on earth.
• Water cycle makes water available in its various forms on the earth. The most important is the rainwater.

This is because water vapour near the cold bottle collides with it, becomes cool, and condenses into water droplets. These water droplets collect and form a puddle of water around the bottle.

Some of the water flows in the form of rivers and streams, the rain water also fills up the lakes and pond, a part of rain water gets absorbed by the ground and seems to disappear in the soil. Some of this water is brought back to the air by the process of evaporation and transpiration.

Hot and dry regions like Rajasthan do not get adequate amount of water. They have to travel long distances for collecting drinking water.

Water in oceans, lakes and ponds gets evaporated due to atmospheric heat. Factories and thermal power stations produce a lot of steam and put it into the atmosphere. Plants throw out water vapour by transpiration. Animals excrete water vapour through respiration and sweating. All this vapour accumulates in the atmosphere.

We obtain food from plants, plants needs water to grow and cook their food by the process of photosynthesis. Water is used in industries for processing large number of things that we uses like fabrics, paper etc,

Roof top rain water harvesting-in this system rain water is collected from roof top to a storage tank through pipes. There is one more method in which rain water is allowed to go into the ground directly from the road side drains that collect rain water.

During the day time, sunlight falls on the water in oceans, rivers and lakes. The fields, roads, rooftops and other land areas also receive sunlight. The sunlight also carries heat with it. As a result, water from oceans, rivers, lakes and the soil, and other land areas gets continuously changed into its vapour.

First, take a clean glass and put some ice cubes in it. Keep it in the open air. After some time, small droplets of water will be observed on the outer surface of the glass. This is because water vapour in the air comes in contact with cold surface of glass and condenses. These droplets of water are due to condensation of water vapour present in the air.

1. Floods damage property.
2. Floods endanger lives of humans and animals.
3. Floods cause soil erosion.
4. Navigation is impaired.

• Rooftop rainwater harvesting: In this system, the rainwater from the rooftop is collected in a storage tank through pipes.
• A big pit is dug near house for collecting rainwater. This pit is filled with different layers of bricks, coarse gravels and sand or granite pieces.

On a clear day, water evaporates from the warm ground into the atmosphere. When night falls, the ground radiates the day's warmth into the skies. The ground becomes much cooler, causing the water vapour to condense. This condensed vapour is dew.

Excess of rainfall leads to many problems. It raises the water level in rivers, lakes and ponds. The water may then spread over larger area causing the situation of floods. The crop fields, forests, villages and cities may get submerged by water.

Yes, spreading of clothes near an angithi or a heater would help dry the clothes quicker. This is because heat generated from an angithi or a heater causes the water to evaporate at a faster rate.

A part of water absorbed by the plants is released by plant through their leaves into the air by a process called transpiration.
Transpiration is affected by the following factors:

• Temperature.
• Humidity.
• Windspeed.
• Time of the day.

On heating, ice (solid water) changes into liquid water and then into water vapour. On condensation, vapours convert into liquid and on freezing, liquid water forms ice.