Cloud Cover

Objective

In this activity, students measure and record the percentage of cloud cover at a selected field site over time.

Making the connection:

  • By measuring and recording cloud cover over a period of time, students can discover how it varies at their field site.
  • By doing this activity with Soil Biodiversity, they can discover what effect cloud cover has on the types of creatures and on the soil at their field site.
  • By doing this activity with Air Temperature, they can see how cloud cover can affect air temperature.
  • By doing this activity with Soil Properties, they can see how cloud cover affects soil properties.

Activity

Hypothesize

What is the percentage of cloud cover at your site?

Plan it!

  • If you haven't already done so, choose a field site and map it in your field journal.
  • If you are doing this activity with Air Temperature and Soil Properties, you should do all of the activities at the same time and place. If you haven't yet done so, decide how often to take cloud cover readings. If you are working with a group or as a class, you should decide together. As you decide, think about these questions:
    • How might your results be affected if you take daily readings?
    • How might your results be affected if you take monthly readings?
    • How might your results be affected if you take annual readings?
    Most scientists would agree that taking readings at least once a week will give you the most accurate record of changes in cloud cover over time.
    Observing cloud cover more often will provide more data, but it is important to be consistent in the frequency of the measurements and in the time of day at which they are taken. Help students create a plan that works with their schedule.

Do it!

  1. Choose a spot in your field area in which to observe the sky. If you are also measuring the air and soil temperature, you should measure the cloud cover at the same time and place.
    By gathering the data at the same time and place, students are able to control those variables. Discuss variables and controls with your students and have them name other variables and suggest ways to control them.
  2. Look at the Environmental Factors worksheet . Imagine that the visible sky is a circle divided into four pieces, just like the circle on your worksheet. Each piece, or quadrant, represents 25% of the whole sky.
  3. Look at one quadrant of the sky. Is it covered by clouds? Is it completely clear? Or somewhere in between?
  4. Sketch the cloud cover for that quadrant on the Environmental Factors worksheet .
  5. Look at each of the other three quadrants. For each, sketch in the cloud cover you see.
  6. Estimate the total cloud cover. If one quadrant is completely filled with clouds, then the cover for that day is 25%. If two are covered, then the cloud cover is 50%. If three are covered, then the cloud cover is 75%. If all four are covered, then the cloud cover is 100%.

Record it!

Remember, be sci-wise!

  • Take the cloud cover readings at the same time of day each time.
  • What if a quadrant has some clouds in it, but isn't filled with clouds? To be counted, a quadrant must be more covered with clouds than not. Do not count a quadrant that has some clouds in it, but is less than half-filled with clouds.

Assessment and Reflections

  • What was the percentage of cloud cover at your site?
    Answers will vary.
  • Based on the data you collected, was your hypothesis correct or incorrect? Why?
    Answers will vary.
  • How did the cloud cover change at your site over time?
    In most places, students should notice some general seasonal trends in cloud cover.
  • How might the time of day have affected the data?
    In some places, clouds tend to gather at certain times of day, particularly during certain seasons. For example, some places experience frequent afternoon rain showers during the summer, although the sky will be perfectly clear during the rest of the day.
  • What patterns or links did you notice between the weather and the cloud cover?
    Students should see a relationship between cloud cover and precipitation or stormy weather.
  • What patterns or links did you notice between the season and the cloud cover?
    In some places, some seasons are rainier or cloudier than others. This will vary depending on where you are.
  • What relationship did you find between the cloud cover and air temperature?
    A high percentage of cloud cover can be associated both with cooler temperatures, as it blocks some of the sun's radiation from reaching the Earth, and with warmer temperatures, as it prevents some of the heat from escaping into the atmosphere.
  • What relationship did you find between the cloud cover and soil temperature?
    Generally, soil temperature fluctuates less than air temperature does, and cloud cover should not have a marked effect on soil temperature.
  • If you continued recording the cloud cover for a whole year, what differences would you expect to find?
    This will vary depending on the field site location. Students might find that certain seasons may experience more consistently cloudy weather, along with increased precipitation.
  • Complete this section on the Factors That Affect the Soil Overview worksheet .
  • Looking at the bigger picture, how might the data you collected here help you to answer your research question?
    Answers will vary, but students should begin to make the connections between the data they gathered in this activity and data they have gathered in other activities.

Extension Activities

  • Have students learn the meteorological terms for different percentages of cloud cover. For example, a day with 100% cloud cover is considered overcast.
  • Have students record the cloud cover each hour for a whole day. Does the percentage change? Would they expect the same thing to happen every day?

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