 Welcome to San Francisco Public Library's Stamp Challenger Self. I'm librarian Joseph. You might remember me from previous challenges as presenter and a host. For this week, I'm super excited to introduce five amazing stamp challenges produced by Yale 2020 interns. For today's challenge, Sharon will guide us on how to make clouds in a jar. Are you ready? Sharon, take over. Hi everyone, welcome back to another episode of Stamp Challenge Yourself. I'm Sharon and I'm a Yale 2020 intern at the San Francisco Public Library. Today, I'll be leading you through the cloud in a jar challenge where I will be explaining more about the concepts of evaporation and condensation, which are processes that are part of the cloud formation process. Now that you know what we'll be doing today, let's begin. So the few materials that you'll need for this experiment are a glass jar with a lid, one third cup of hot water, four to five ice cubes, hairspray and a few drops of dye. Now feel free to pause the video and gather your materials before coming back to start this experiment. Now that we have all our materials ready, let's begin by putting blue dye into the warm water in order to later be able to distinguish between the cloud and the blue water. So take a few drops and drop it in and swirl it around to mix the dye. With your dye warm water, start by pouring the hot water into the jar. Then swirl it around the side to warm the sides up a bit. After this, take your lid and put it upside down. Then take your ice cubes onto the lid and then put it right on top. Now let this set for about 20 seconds. A few moments later. When it has been 20 seconds, carefully remove the lid, keeping the ice on top, and take your hairspray and spray a bit of it into the jar. Then quickly put on your, and now all you have to do is sit back and wait for the cloud to form. When you see a good amount of condensation form, remove the lid and watch the cloud escape. Now that you created your very own cloud, you must be wondering how does this work? Well to answer that, we need to first understand how clouds form. So we begin the cloud formation process with the sun heating up the earth. More specifically, our oceans inland. From there, the heat from the sun causes the air and water molecules at ground level to heat up and rise to become water vapor. This process is called evaporation, which is a process where water changes from a liquid to a gas. Although this process does not require the sun, it does happen quicker when the sun is present because the heat it gives off warms up the water molecules to move faster and faster and become gas. We represented evaporation by pouring warm water in the jar and trapping it because by doing so we created water vapor. Now to continue with the cloud formation process, as the water vapor created from evaporation rises higher and higher, the cool air of the atmosphere causes the water vapor to turn into sticky water droplets. From there, these sticky droplets combine with other particles floating around in the sky and form clouds. This intriguing process is condensation. Condensation was represented in our experiment when the water vapor from the warm water rose up and cooled down and became water droplets due to our ice cubes at the top. Then, by spraying hairspray, which is sticky, the fumes of the hairspray help the water droplets cling together and form our miniature cloud. Now that you have a better understanding of our cloud concepts, how about some cloud trivia? As you answer these questions, feel free to pause the video if you feel that you need more time. Question number one. What evaporates quicker? Warm water or cold water? The answer is warm water because the rate of evaporation actually increases as the temperature increases. Question number two. What happens when the water vapor hits the cool air? When the water vapor hits the cool air, it actually becomes liquid again. Question number three. What is it called when water droplets form a cloud? Condensation is the process where water droplets form a cloud by combining with particles in the sky. Well, that is all the time we have left for today. I hope you had fun creating your very own cloud in a jar. If you enjoyed this experiment, make sure to check out sfpl.org so you can access the many resources we have provided. Also, make sure to check out our Instagram at sfpubliclibrary and at the mix at sfpl to get notified when we have other STEM challenges. Anyways, thanks for watching. Bye!