The Water Cycle Explained: How Water Shapes the Planet We Live On
Throughout the project, you’ll see a number of incredible athletes, however one of the key characters is water itself, simply because, our world is defined by it.
Water gives us the fluid we drink, the seas we sail on, and the snow we ski on. Most of our planet is covered with it. Most of our bodies are made of it. And it never stops moving.
The ocean’s currents and mountains rhythms are central to that – but they’re not the full story. The water on our planet is engaged in an endless cycle of renewal, from sea to cloud, to rain or snow, and back again.
But just how does this incredible journey work? And what role does the ocean play in it? Let's find out..
Water Cycle 101
The water cycle, also known as the hydrologic cycle, is how we explain the natural movement of water across the world. It's part of the mechanism of life on our planet: water from Earth’s surface evaporates into the atmosphere and then falls back down to the ground. It’s what creates clouds, rain and snow. It’s a process that’s been going on, continuously, for billions of years, and without it our planet would be uninhabitable.
The water cycle is a naturally occurring delivery system pumping life-giving water across the globe. It provides fresh water, which is needed for drinking, food production and generating power. The water cycle also has a big effect on our climate. It helps move heat around the earth and plays a big part in controlling temperatures. Over time, water has even helped shape the land, carving out valleys, eroding mountains and forming rivers.
Evaporation
The first phase of the cycle is called evaporation and this is where the ocean really comes into force. According to the United States Geological Survey (USGS), water covers 70% of the earth, and 97% of the earth’s water can be found in the oceans. The heat from the sun evaporates the water, turning it from a liquid to a gas, or vapor, which rises into the sky.
Water gives us the fluid we drink, the seas we sail on, and the snow we ski on.
Condensation and precipitation
Cooler temperatures far above the earth’s surface then condense the vapor back into tiny droplets of liquid that gather to form clouds. This is known as condensation. When the droplets in the clouds become too heavy, they fall back to the ground as rain, snow, sleet, or hail, which collectively we call precipitation.
Infiltration and groundwater
Some of the falling water seeps into the soil to be absorbed by plant roots and contribute to new growth, starting the cycle anew, in a process called “infiltration.” It can also continue to move downwards until it reaches the water table and joins a groundwater reservoir. Groundwater is vital as it feeds into our rivers and lakes, maintaining their levels and providing a source of water during times of less precipitation. It's also a crucial source of drinking water.
Surface runoff and rivers
Not all water infiltrates the soil. Some of it travels over the ground surface, particularly when the precipitation is heavy and falls faster than it can be absorbed, with the excess water flowing into streams and rivers. The process is known as “surface runoff” and carries water across vast distances, via rivers and streams, eventually depositing it back into the ocean.
The vital role of snow and ice
In colder climates, precipitation often falls as snow. The snow can accumulate and compact over time, forming ice and contributing to glaciers, locking the water into a solid state and preventing surface runoff. Snow and ice act as a natural reservoir that releases water into rivers when the weather becomes warmer – especially useful in regions where summer precipitation is low but demand for water is high. Learn more about snow science with scientist Todd Redpath.
This exchange of energy and the never-ending transportation of water around the Earth is happening every second of every day and the health of our ocean plays a crucial role in how our world functions. According to the UN, our seas generate 50% of the oxygen we need, and absorb 25% of the carbon dioxide and 90% of the excess heat from mankind’s emissions, making our planet’s waters even more vital as the climate crisis continues to exhort its toll. The water cycle clearly shows us that unless the ocean is thriving, the planet we live on cannot thrive either.