What is the water cycle?

As the title suggests, this blog post seeks to define what the water cycle is, how it works and the role of glaciers in the water cycle.

What is the water cycle?

According to the National Oceanic and Atmospheric Administration, the water cycle is “the continuous movement of water on earth and in the earth's atmosphere.” 

How does it work?

At a basic level the water cycle is understood as a cycle of evaporation, condensation and precipitation. For the sake of understanding, let us begin with a water molecule in the form of a snowflake. The snowflake lands on the surface of the earth, perhaps it meets the surface of a glacier and becomes ice. In time, that ice will melt, eventually becoming water. As water, the molecule might join other water molecules as runoff into a river, lake or ocean, or it might evaporate and become a cloud, eventually returning to the earth as precipitation. When the water joins a lake or a river, it infiltrates and percolates into the ground where plants absorb the moisture and underground water sources are replenished.

Water molecules on the glacier have several paths for transformation. An obvious transformation is from solid (ice), to liquid (water) during a melt for example. Less obvious water molecule transformations that can take place on a glacier are sublimation and deposition.

Sublimation is a process where snow and ice are transformed directly into water vapour, skipping the liquid state completely. An example of this is shown in the image below.

sublimation on the mountain

What looks like rolling clouds is actually sublimation in action according to veteran guide Corin Lohmann. The molecules transformed by sublimation will eventually be transported and converted into precipitation and continue their journey through the water cycle.

The opposite of sublimation is deposition where water vapour transforms directly into a solid form. Frost would be the solid form that most readily comes to mind.

There are many ways to study water and its cycles. There are hydrologists, who study the movement of water on the earths surface and glaciologists, who study the physical properties of snow and ice, to name a few.

*the thumbnail image is licensed under the Creative CommonsAttribution-Share Alike 4.0 International license.

Rachael Thomas

Rachael is an Urban Planning and Sustainability student at Concordia and a concerned, sometimes anxious and curious global citizen with regards to climate change. Also a former visitor of the Athabasca glacier, the experience of leaving the walking tour left her both amazed and concerned with a sense of dread for the future of the glacier and the ecosystems it interacts with. Together with the generous funding of ECO Canada, the mentorship of Megan Lohmann and the power of a Concordia University library card, this series will explore what a glacier is, the role of the Athabasca glacier as a water source, how the glacier is impacted by climate change and what concerned climate citizens like you can do to mitigate the damage of climate change in our everyday lives.

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