Clouds

Clouds float and change across the sky Some are billowy, I do not know why. They can be white and pink and gray They change with the weather everyday. Are they the pillows in the sky? Or are they blankets for planes that fly by? I like to sit and spend the day Watching the clouds drift away. Author: Genevieve A. Davis

Clouds are part of our daily experiences. At one time or another, we have been awestruck and mesmerized as we gazed up at the clouds. Children and adults can watch them move and see them create wonderful art forms right before our eyes. They affect us in many ways. They can be a determining factor in planning our outdoor events. “Why is it always cloudy on weekends?” “Will clouds cover the eclipse of the moon or a coming meteor shower?” Baseball players often like to play when it’s cloudy because clouds keep the sun out of their eyes.

Clouds contribute to our demeanor. Some clouds cause us to dream, to slow down the pace of life. At times clouds, which provide the steady rain that we can hear on the roof, cause us to be somber or pensive. Other times, in strong winds, storm clouds seem to be musical or perhaps frightening. Leah Polacco’s book Thunder Cake is a story about how Patricia Polacco conquered her childhood fear of Michigan thunderstorms with the help of her caring grandmother. This book can be a great story starter for young children who may have experienced similar emotions during a loud thunderstorm.

Other emotions are also tapped when weather-watching. It is a wonderful experience to see the sun peak in and out of clouds, especially if we are trying to keep warm with the sun’s rays. Watching the moon dance in and out of the clouds can give special significance to tall stories around an autumn campfire or other outdoor experiences.

Clouds are great communicators. They tell us many things. Clouds give us an indication about what the weather is going to be like. When we see fluffy cumulus clouds that look like small pillows in the sky, we expect a beautiful day. Seeing the high cirrus “mares’ tails” often indicates that it might rain a day or two in the future. Many sayings have been developed over the centuries relating weather predictions to the clouds, such as “Red sky at night, sailor’s delight. Red sky in the morn, sailor be warned!”

Clouds are the basis for the Concept Explorations in this chapter for many reasons. First, they are a major factor in our daily lives. Clouds are everywhere in the whole wide world and provide endless fascination to all who observe them. We interact with clouds in one way or another each day. This factor gives reality to your children’s learning. Having a basic knowledge about the nature of clouds also is critical for comprehending many other natural scientific processes. The interconnectedness we have with nature provides wondrous phenomena to ponder and explore.

Clouds are the basis for the nature of our environment. Without clouds we would have no precipitation. Without precipitation there could be no lakes, no rivers, no streams no erosion and no weathering of rocks. Without precipitation, vegetation as we know it would not exist. Animals would have no food. In this sense, looking at the nature of clouds gives us a basis for looking at all of nature.

Clouds give us opportunities to observe change. Developing skills in observing changes is an important part of science and mathematics. Documenting changes helps to develop the concept of order and sequence. Documenting changes is also valuable for developing skills in organizing, analyzing, and displaying data through basic charts and graphs. Obviously, these skills are also paramount in developing other basic mathematics skills such as determining length, volume, mass, temperature, and speed.

As you look at the development and understandings of your students, you can select and plan activities from the explorations presented in this chapter that present opportunities for your children to apply specific skill areas.

Science Concepts for Teachers

The science conceptual framework included here is designed to give background information about clouds, their formation, and their effect on climate and the environment. Its purpose is to give you background knowledge to assist you in your teaching. It is not intended as instructional material for the children, but instead to give you a framework to ensure that what you teach is indeed accurate and factual in nature. Having a basic knowledge of how clouds form and change is valuable for you as a teacher. This knowledge will help you recognize opportunities to share with your students about the roles clouds play in many natural processes. Throughout your life, your knowledge will continue to grow. In addition, as scientists uncover new ideas and knowledge, you will be able to better understand these processes and patterns of nature. These developments assist us in communicating ideas to our students.

The concepts and information provided here should only be presented to the children at an introductory level. For example, when a thunderstorm occurs, you might ease the distress of some of the students by pointing out characteristics of the storm clouds. As you and your class observe the development of the storm, you might encourage your children to predict what will happen. However, it would not be appropriate to expect your children to understand the specifics of lightning and thunder.

What Causes Clouds?

Clouds form when there is more water vapor in the air than the air can hold. When this occurs, water molecules will form around hygroscopic particles, forming water droplets or, if it is very cold, ice crystals. Hygroscopic particles are extremely small particles of matter that are suspended in air. Many hygroscopic particles are minute particles of salt that are formed by the evaporation of water sprayed by ocean waves.

The greater the amount of water in the air, the larger the water droplets become. At some stage, the water droplets can no longer be suspended by the air and precipitation occurs.

The larger the cloud, the greater the amount of moisture in the air. It is difficult to imagine how much water is in a cloud until that cloud emits a heavy rain. For example, during a 24-hour period, 43 inches of rain fell over a portion of Texas. If you have ever seen a flash flood caused by the action of a downburst, you can start to visualize the amount of water that is in a cloud.

Clouds often indicate an upward movement of air. As air rises, it becomes less dense and the air temperature lowers from 2 to 5 degrees Fahrenheit (1 to 3 degrees Celsius) for each 1,000 feet of height. This lowering of the air temperature increases the humidity. At 100% humidity, the air cannot hold any additional water vapor. At that point, water droplets (or if the air temperature is below 32 degrees F, or 0 degrees C, ice crystals) are produced, forming clouds. Fog is simply a cloud that is at the surface of the earth.

Types of Clouds

Each cloud has unique properties that meteorologists use to classify clouds. They have identified three basic types of clouds: cumulus, stratus, and cirrus.

Cumulus clouds are low-altitude, billowy clouds that are usually dark on the bottom while the top resembles a giant white cotton ball. Small cumulus clouds can indicate “fair skies.” A cumulus cloud may be relatively tall, extending from a base at around 2,000 feet to a top near 10,000 feet above the ground. Large cumulus clouds cast dark shadows and may be a source of moisture, but generally produce no more than a summer shower.

Stratus clouds are wispy foglike clouds that hover a few hundred feet above the ground, sometimes obscuring hills or tall buildings. They may begin as ground fog and can be a source of drizzle. They tend to cover most, if not all, of the sky.

Cirrus clouds are generally the highest clouds, forming “mares’ tails” at altitudes between 20,000 and 40,000 feet. The clouds may appear as delicate white filaments, feather-like tufts, or fibrous bands of ice crystals. Cirrus clouds are not a source of precipitation.

Because clouds actually are much more diverse than just the three basic types discussed above, meteorologists also classify clouds by identifying characteristics that include properties of two of the basic forms of clouds. For example, cirrocumulus clouds have properties of both cirrus and cumulus clouds. They have the loosely packed sheets of small white cloud segments often associated with cumulus clouds, but these segments can dominate and cover the sky, as is typically seen with stratus clouds. Cirrostratus clouds show the characteristics of both cirrus and stratus clouds.

Clouds that are delivering rain are often given the suffix -nimbus. For instance, a cumulonimbus cloud is a large cumulus cloud associated with thunderstorm clouds. These clouds can vary considerably in altitude from ominously dark lower portions below 5,000 feet to white anvil-shaped tops that may reach upward to 50,000 feet. They contain large amounts of moisture, some of which may be in the form of hail. The cumulonimbus cloud may appear alone or as part of a wall of advancing storm clouds.

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