Have you ever wondered why it rains when it does? Or how puddles disappear? All of this is part of the water cycle, or the hydrologic cycle. When you look at an ocean or a lake, it might seem like it is always the same, but water is actually always moving. That's why it's called the water cycle- it never ends! Pretty cool, huh? Let's talk about how it works.
Let's start with clouds. You may know that clouds are made up of tiny invisible water droplets. But where do these water droplets come from? They start with a process called evaporation.
So now we know how water droplets get into the air, but how do they become clouds? That happens once lots of the individual droplets travel way up through the atmosphere and start to come together. This process is called condensation.
Once clouds have formed through the process of condensation, all that's left is for it to rain again so the water droplets return to earth. But how does that happen? Eventually, enough water droplets come together so that a process called precipitation occurs.
What happens when the water reaches the earth's surface? It flows on the earth's surface and some of it soaks into the ground- this is called recharge. The water gets soaked into the soil and travels down deep into the ground until eventually it becomes groundwater and is stored in a below-ground aquifer. These aquifers are where most people get their drinking water from!
Water doesn't just stay still when it reaches an aquifer though. It is constantly involved in a process called groundwater flow, where it slowly moves through all the different rocks and soil particles in the ground to get deeper and deeper. Eventually, sometimes years later, the groundwater droplets will reach a discharge area like a lake or a stream.
And what happens next? Well, eventually the water will evaporate and move through the water cycle again!
Water Cycle Experiments
Want to learn more about the water cycle? Try one of these fun experiments to see how each of the three processes work!
Evaporation: Get two bowls of the same size and pour one cup of water into each bowl. Measure the depth of the water in each. Place one bowl in a sunny area and the other in a shady spot. Leave the bowls for one hour, then measure the depth again. Is it the same? Does the sun affect the result?
Condensation: You will need a clear plastic cup with a wide rim and another clear cup with a smaller rim for this experiment. Ask your mom or dad to pour some hot water into the cup with the wide rim, and then place the cup with a smaller rim upside down on top of the water to cover it up. Watch the cups for 2 minutes to see what happens. Feel the inside of the top cup. What process did you just observe?
Evaporation, Condensation & Precipitation: Fill a small Dixie cup with water and place it in a sealed plastic bag. Tape the bag inside on a window that receives a lot of sunlight. Observe what happens- you will see the water disappear and droplets form on the outside of the bag and then run down the sides. Can you name which process of the water cycle goes with each observation?
Pictures provided by http://www.openclipart.org