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Water and Oceans
Factfile |
 Water and Oceans |
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The Water Cycle |
- The amount of water in our oceans and seas stays about the same - but how does that happen? After all, seawater has been around for millions and millions of years, why haven't we run out of it? The amount of water in the sea actually stays about the same because of the Hydrological Cycle or Water Cycle and here is how it works:
The Sun is the power source behind the Water Cycle. As the Sun heats up rivers, lakes, oceans and even puddles, the heat causes the surface of the water to Evaporate. This means the water has turned from a liquid to a vapour, water in a gas form and invisible in the air. The vapour is then lifted up into the atmosphere on warm air currents.
As the vapour reaches the cooler layers of the atmosphere, it cools down. As it does so, it condenses, or turns back to into tiny droplets of water, forming the clouds, mist or haze that covers our planet. (Our ever-changing cloud patterns are a result of old clouds constantly re-evaporating and forming new ones).
Once formed, these clouds might get blown on land (clouds protect our Earth from the heat of the Sun). As the clouds grow in size, the clouds will become too heavy with droplets. Eventually, these then fall back to Earth as Precipitation. (Depending on other conditions at this time, Precipitation can fall as rain, snow or hail). Once on land, the Water Cycle can start again.
Animals and plants also contribute to the Water Cycle. Animals and plants loose water in the form of water vapour through their pores. This process is called Transpiration. Think of your breath on a very cold day. The steam that you blow out is in fact water vapour. Once you have blown it out, it will start the process of returning to the atmosphere (and so start the Water Cycle process again).
Each time a drop of water goes through the Water Cycle, it is purified or cleaned and animals and plants can use it again and again (and again!). However, this also means that at some point in the past, the water in your next glass of water could have been a gas, solid or liquid many times over. Just think, it is quite possible that a dinosaur could have swum the water you are about to drink!
As water is essential for all life on Earth - so how important is seawater here?
The Water Cycle
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