The Importance of Water Cycle

​Points to Remember:  The water part of the Earth is called hydrosphere or “water sphere”. This covers about three-fourths of its surface.  Water cycle is a continuous process of changing liquid water into water vapor (gas) when heated and turns back to liquid water when cooled above and below the surface of the Earth. Water is transferred from the Earth’s surface to the atmosphere through evaporation. Bodies of water, clouds, evaporation, and condensation including living things all play important roles in the water cycle.  The Sun plays a major role in the water cycle. It is the main source of heat that causes evaporation process

​Processes involved in water cycle:

1. Evaporation - is the process of changing liquid water into water vapor (gas) and rises into the atmosphere. Roughly 80% of all evaporation comes from oceans while the remaining 20% comes from inland water and plant vegetation. More evaporation happens when the temperature is high and with faster wind speed.

2. Transpiration – takes place during evaporation process wherein water particles are released from the leaves of the plants and vegetation. The rate of transpiration gets higher with higher temperatures.

 Respiration - takes place when animals and humans breathe out water particles through their lungs and when they perspire, which evaporates into the atmosphere in lesser amounts. Animals contribute to the water cycle through respiration, perspiration and urination.​

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​3. Condensation - is the process of changing water vapor (gas) into tiny droplets of liquid water in the form of clouds in the atmosphere. Condensation can be high in the atmosphere or at ground level. Water vapor condenses around tiny particles called cloud condensation nuclei (CCN). The cloud condensation nuclei can sometimes be specks of dust, salt, or pollutants. As tiny water droplets combine with each other, clouds develop, and precipitation may occur.

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4. Precipitation - is the process by which the tiny condensed water droplets falls back into the Earth’s surface in the form of rain, hail, snow and sleet. Although there is a continuous cycle of water, you might wonder if there will come a time when we will run out of water. Did you know that 97% of the water found in our surrounding is salty? Thus only 3% of this water is fresh or potable. This very small amount of freshwater is 67% locked in the form of ice mainly found in Greenland and Antarctic. Therefore, only about 1% of freshwater is found in rivers, lakes, ponds, and in the atmosphere in the form of water vapor.​

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