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Sky Color for Kids


Science Project:  Sky Color for Kids
A clear, blue sky north of Hilo on the island of Hawaii
Image courtesy Forrest M. Mims III
Web Id: P11
Purpose: In this activity we will introduce children to the colors of the sky. Children love to look at clouds. Here we will focus in on the sky in which clouds float. Children will learn why the sky has such a wide range of colors.
Age Range: 6 to 10
Time Required: You can teach children the basic facts about sky color in two brief sessions of 5 to 10 minutes each. For best results, one session should be indoors and the other outdoors or in a room with a window or windows having an unobstructed view of the sky. For a more memorable experience, spend some time with your students so they can more fully appreciate and talk about the sky and its appearance and colors.
Background:

The sun is blinding white, but a clean sky is blue. How can this be? Click here to find out.

Young students need to know that white light from the sun is actually a combination of the colors violet, blue, green, yellow and red. We know this because of the rainbow that is formed when rain droplets divide the white light from the sun into its various colors.

Why is the sky blue? Molecules of air scatter the blue colors of sunlight much more effectively than the green and red colors. Therefore, a clean sky appears blue.

Air pollution and natural haze can cause the sky to appear light blue or even milky white. Air pollution can cause the sky over the horizon to appear brown or gray.

Significance:

Many people, and this includes children, do not pay much attention to the sky when they are outdoors. Teachers can prove this simply by asking their class ‘What color is the sky today?’ Chances are that most students will not know. The significance of this project is that students will learn to appreciate the colors of the sky and what they mean. They will learn how natural haze, air pollution and giant volcano eruptions can alter the color of the sky.

Procedure:

The best way for kids to learn about sky color is for them to look at the sky on different days. This is best done outdoors, but sky watching can also be done through a clean window, preferably when the sun is away from the window.

Explain to children that a deep blue color means a very clean sky. A deep blue sky can occur when a cold front brings in clean air from the north. A deep blue sky can also occur when clean air from over the ocean blows over the land.

A medium blue sky suggests there might be plenty of water vapor in the sky. It can also mean the presence of sulfur from coal burning power plants, chemical factories and natural sources.

A pale or milky white sky suggests the possibility of considerable air pollution, often in the form of sulfur from coal-burning power plants. In some areas this condition occurs mainly in summer when the air is still and pollution accumulates.

Smoke can cause the sky over the horizon to look gray or dark gray.

Pollution from cars and trucks can cause a layer of brown or brownish orange pollution over the horizon.

Major volcano eruptions can cause a hazy sky that can last for several years and cause the sky to appear brown.

Discussion is an important part of sky watching. Ask children to describe the sky as they see it.

What color is the sky near the horizon?

What color is the sky well above the horizon?

What color is the sky straight overhead?

Ask your students to classify the sky according to the colors recommended by the GLOBE Program:

Deep blue (unusually clear)
Blue (clear)
Light blue (somewhat hazy)
Pale blue (very hazy)
Milky (extremely hazy)

Severe air pollution, including smoke plumes from agricultural and forest fires and giant volcano eruptions that may occur every 10-20 years, may alter these colors.

Teachers and parents, please be aware that some boys may be red-green color blind. While they should be able to see the blue hue of the sky as well as other children, they might not perceive subtle differences in the colors of a polluted sky the same way.

Caution: Always be safe and alert to your surroundings when sky watching. Children should be careful if they are walking while looking up at the sky. The sky scatters much of the sun’s ultraviolet rays, so sky watchers should wear sunglasses if at all possible, especially during the summer. Children should never look at or near the sun! Instead, they should watch the sky with their backs to the sun.

The projects that follow might make good science fair projects, so keep that in mind as you try them.

Project Links:

What Color is the Sky? is a Scholastic site with various sky activities and good ideas for discussing sky color with very young students.

The GLOBE Program has a very nice protocol for Observing Visibility and Sky Color.

Sun and Sky includes a variety of unusual sky color photographs.
Real Time Data Source:

MODIS Rapid Response
LANDSAT Image Viewer
MY NASA DATA Source:

Aerosols and Carbon Monoxide
Project Ideas:

1. Make a Sky Calendar. You will need a set of colored pencils or crayons and a calendar for this project. The GLOBE Program calendar is excellent, because it includes spaces to both color the sky and write down what you see. You can also use a calendar from a store or a calendar printed by a computer. Or you can make your own calendar using a ruler and a blank sheet of paper. Be sure to keep your sky calendar in a safe place.

After you get your calendar, practice making different shades of blue on a sheet of blank paper using crayons or colored pencils. Begin your sky calendar by coloring in the first day with the color of the sky. Each day you should color the next box in the calendar with the sky color. You should do the project for at least one week. For best results, do the project for one month. This will provide you with a record of the sky color for your area. The sky calendar will reveal much about air pollution and haze–if they are present. If possible, protect your sky calendar by sliding it inside a plastic sheet protector.

Tip: See the ‘Going Further’ section below for how to make a sky calendar using a camera.

2. Make a Sky Bottle. You can use water and a few drops of milk to demonstrate a clear and a hazy sky. Pour some clean water into a clear bottle and pretend it is the sky. Then place a drop of milk in the bottle and shake the water. The milk can be thought of as natural haze or air pollution. The ‘sky’ will not be quite as clear after you shake the sky bottle, especially if you dim the lights and shine a flashlight through the bottle. Add another drop of milk and shake the bottle again. The ‘sky’ will look hazier than before. Continue adding drops of milk to increase the haze in the sky bottle.

If you place the flashlight close to the bottle, you might notice that the beam of light looks bluish. That’s because the molecules in the milk scatter the red colors of light, leaving behind the blue colors. The same thing happens when sunlight passes through the sky.


Tip: If you don’t have a bottle, use a glass of water for your ‘sky.’ Stir the water with a spoon after adding each drop of milk.

3. Paint the Sky. There is a difference in the color of the sky overhead and the color of the sky over the distant horizon. Children can learn that the horizon is the best place to look to check on the cleanliness of the sky. Have children face away from the sun and look up into the sky. If it is a fair day with little haze, the sky overhead will be blue. Next, have the children look down to where the sky meets the horizon. Chances are the sky over the horizon will be a very different color than the sky above. If there is no air pollution, the sky over the horizon will be very light blue. Air pollution or natural haze might cause the sky to look more white than blue. Air pollution, blowing dust and smoke can all cause the sky over the horizon to appear gray, dark gray or brown. Children can try to capture these subtle color differences using colored pencils, crayons or paints.

4. Look at Your Shadow. The sky controls how your shadow appears. On a day when the sky is clear and deep blue, shadows appear dark and very sharply outlined. On a hazy day, shadows are fuzzy and not as dark. Children can see this for themselves when they go outdoors when the sun is not blocked by clouds. They can also notice the difference in how the ground under a tree looks on a clear blue day and a hazy day. On a clear day, the leaves form distinct, dark shadows on the ground. On a hazy day, the shadows are not as dark. Children can sketch their shadows on clear and hazy days to illustrate the effect of the sky.

Note: Mention of commercial products does not imply that they are endorsed by NASA.
Analysis Ideas:

Using your Sky Calendar, Sky paintings, or Shadow drawings, think about how the sky has changed over a week or a month’s time. What are some factors that could explain these changes?
Related Projects:

GLOBE
Questions:

1. Which sky is cleaner: (a) Deep blue, (b) light blue, (d) milky blue?

2. Air pollution can cause the sky to be (a) white, (b) brown, (c) gray, (d) all the above.

3. What is the best way to protect your eyes when looking at the sky?

4. Can the the color of the sky tell you anything about the weather?
Going Further:

Here’s a good project idea for your school science fair: Make a sky photo album using pictures of the sky that you make with a disposable film camera or a digital camera. You can even use a cell phone camera, but the pictures will not be very sharp. Try to take pictures when the sky is very clear, hazy and polluted. For best results, take pictures of the sky over the horizon with your back to the sun. After you have a collection of pictures showing the color of the sky, place them on your science project poster and add explanations that describe each picture.

You can expand this idea by making the sky calendar described above using photographs instead of coloring each day with colored pencils or crayons.

Project ideas contributed by Forrest M. Mims III