Wednesday, July 10, 2019

It's Water-Wise Wednesdays with Frannie the Fish! {The Water Cycle: Part 6 - Condensation}

This is the sixth part of Frannie’s exploration of the water cycle. Please check out her previous blog on the overview of the water cycle and her deep dives into groundwaterdischargesurface water, and evaporation.

Welcome back to Frannie’s exploration of the water cycle! Condensation is represented by the white bead on Frannie’s water cycle bracelet. Before we can understand condensation, we have to look at one of water’s coolest properties.

Water droplets have 2 amazing superpowers. The first one is called “cohesion”, which means that the molecules like to stick together. You can see this water property in action with a very simple experiment.

1) Fill a glass of water to the rim.
2) Once it looks full, continue to add water drop by drop.

Even though the water is technically over the rim of the glass, it isn’t spilling because the drops are cohering to each other.

A water droplet's second superpower is known as "adhesion", which means that molecules like to stick to other things. You can see this water property in action in another very simple experiment.

1) On a warm day, fill up a glass with ice and water.
2) Leave it out on a table for a few minutes.

Observe the water that collects on the outside of the glass. The glass isn't leaking - water vapor from the air is cooling down and sticking, or adhering, to the outside of the glass.

After water vapor rises into the air, it starts to cool and seek out non-gaseous particles, known as Cloud Condensation Nuclei (CCNs). When water vapor makes contact with CCNs, it adheres. It then cools and transitions from vapor to liquid droplets, as clouds would have in low and intermediate elevations, or solid ice crystals, as clouds would have high up in the atmosphere. Clouds grow when more water molecules cool and cohere together in the process known as condensation.

Condensation is an exothermic process, which means it releases heat. Convection, which is movement of a fluid in response to heat, and advection, which is the movement of a material that is suspended in a fluid such as a CCN, are two other important processes at this stage in the water cycle.  They are responsible not only for carrying clouds over the ocean and land, but also for our next step in the water cycle – the precipitation of water from the clouds.

Join Frannie next time as she heads back down to the ground with precipitation!

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