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Weather or Not (Cloud Formation/Condensation)

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  • As the saying goes, "April showers brings May flowers." but where does rain come from? Most people realize that it has something to do with clouds, but what causes clouds to form in the first place? This investigation goes deep inside a cloud to discover exactly what makes them tick. If you ever wanted to find out how clouds rain on a parade, I've got a challenge for you!

    Here's what you'll need to participate:

    • 2 clean, large glass jars the same size (pickle or mayonnaise jars work well) or two identical clear plastic glasses
    • 2 large (12-inch) latex balloons
    • a pair of scissors
    • some warm water
    • some chalk dust or smoke
    • 4 to 6 large thick rubber bands
    • a red crayon
    • a freezer, refrigerator, ice chest, or cold day

    Begin by cutting the ends off of the two balloons, then get a couple of dusty chalkboard erasers and stand ready.

    If you have ever watched clouds, sometimes it seems that they form out of nowhere. Clouds form because as the air cools, the water vapor contained in it begins to condense. But is temperature the only factor that controls how fast a cloud forms? In this experiment, you're going to see if the amount of dust present in the air has an effect on cloud formation as well. Using two jars, you are going to set up a controlled experiment that will produce a cloud in a bottle!

    Okay, here's the challenge question:

    Does dust in the air help to make clouds form?

    What you do:

    Begin by predicting which jar will form a better cloud — one with dust and water or one with pure water. Make sure you explain why you think this might happen. After you've made your predictions, put a few drops of warm water into the bottom of each jar. Take one cut balloon and stretch it completely over the top of the first jar and wrap 2 or 3 rubber bands around the top edge to make sure that the balloon makes a tight seal. Next, clap a dusty chalkboard eraser over the top of the second jar and seal it up with the second balloon the same way you did the first. Label this jar with the crayon by putting a big X on the side. Place both jars in a cool place for about 10 minutes.

    When the time is up, take the two jars out and compare the insides. Are they the same? Try pulling up on the top of the two balloons. Any changes in the jars? How might this experiment help meteorologists predict the weather?

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    Notes to Teachers

    Curriculum Focus: Science/Weather/Cloud Formation

    Learning Outcomes:

    • Observe the condensation of water in two sealed jars — one with just water, and one with water and chalk dust.
    • Predict how the dust will affect cloud formation.
    • Discuss how the presence of dust helps meteorologists make forecasts.

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    Web Links

    Try these sites for more cloud and weather-related information and activities.

    Cloud Catalog
    This targeted site contains descriptions and images of the various types of clouds in our atmosphere. There is a glossary of important terminology provided for the less familiar terms.

    Dan's Wild Weather Watch Page
    A complete weather center for all grade levels. There are learning centers for each area of weather, from clouds to radar.

    USA Today: Weather
    This site offers a comprehensive view of all aspects of weather, focusing on current weather events as well as historical information. It offers support materials for the study of weather.

    The Weather Underground
    This site provides weather forecasts, current conditions, and curriculum materials. There is free downloadable software for interactive weather maps, as well as organized interactive units about weather observation and hurricanes. Other units are in the works for the coming seasons.

    The Weather Channel
    Complete weather information is provided for the United States and for countries around the world. Weather history, weather vocabulary, and lots of other related material is included. Teacher resources — on topics such as heat index, wind chill, and becoming a meteorologist — and classroom support are available.

    Online Guide to Meteorology
    Multimedia modules that introduce and educate students on selected topics in atmospheric science are provided here, complete with data, explanatory text, large images, maps, and even eyewitness accounts of a tornado.

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