Atmospheric Moisture Assignment (Cloud-In-A-Bottle Experiment)
This assignment is a little different. Instead of having you respond to critical thinking questions, you are going to perform an experiment and post an image of your results. For this assignment you will only need to submit an image, worth 20 points.
I. Complete the following for your assignment:
This week you are learning about atmospheric moisture, clouds, and cloud formation. For this assignment you are going to create your own “cloud in a bottle”.
Here is what you’ll need:
- A 2-liter clear plastic bottle with cap (I recommend using a clear, 2-liter, plastic soda bottle). Be sure to take the label off so you can see your cloud inside. Note: glass bottles/containers will not work. You will receive a “zero” for this assignment if you use a glass bottle because you will not be able to change the pressure and thus generate a cloud (this happened for the first time last year so please read and follow the instructions). Smaller plastic bottles can work but you may have difficulty viewing/taking a picture of your cloud.
- Matches (at least two).
- Small amount of warm/hot water (about 0.5 – 1 cup for a 2-liter bottle). The hotter the water, the better. But do notboil the water since obviously it may melt the plastic.
Process:
Fill the clear, plastic 2-liter bottle with the warm water and place the cap on. As the warm water evaporates, it adds water vapor to the air inside the bottle. This is the first step in cloud formation – saturation (aka humidity).
Now, you are going to change the air pressure in the bottle. Put the cap on the bottle, then squeeze and release the bottle and observe what happens. You’ll notice that nothing happens. Why? The squeeze represents the warming that occurs in the atmosphere. When you increase the pressure in the bottle by squeezing it, the air molecules collide and bump up against one another, creating friction. This friction generates heat. Releasing the bottle represents the cooling that occurs in the atmosphere. When you decrease the pressure, the molecules are able to spread out and away from one another, lessening the chance of friction. This spreading-out results in a loss of heat. If the inside of the bottle becomes covered with condensation or water droplets, just shake the bottle to get rid of them.
So, thus far you haven’t created a cloud. You’re still missing a piece. Take the cap off the bottle. Carefully light a match and hold the match near the opening of the bottle. This will allow some of the smoke to enter the bottle.
Then drop the match into the bottle and quickly put the cap on, trapping the smoke inside. Dust, smoke, or the particles in the air are a vital component to cloud formation. Water needs a surface to condense on – the smoke from the match will provide the surface.
Once again, slowly squeeze the bottle hard and release. What happens? A cloud should appear when you release and disappear when you squeeze. Why? By squeezing the bottle, air pressure and temperature dropped allowing water to condense on the smoke particles from the match and form a cloud! Ta-Da!
Take a picture of your cloud in the bottle and submit it for this assignment. This should be an original image that you have taken (since the point is for you to have completed the experiment yourself). Images taken from online and/or other sources will not receive any credit. You do not need to write anything unless you want to. I am simply giving you full credit for successfully completing the experiment and creating your cloud.
If your experiment did not work, try again! You may not have enough warm water and/or enough smoke in the bottle. If you squeeze and release the bottle multiple times your cloud should appear thicker. Here is link for a helpful video of what your cloud should look like – Making Clouds in a Bottle
Links:
https://www.youtube.com/watch?v=32uFVssBs6E
http://www.earthonlinemedia.com/ebooks/tpe_3e/atmospheric_moisture/title_page.html