# What Makes Thunderstorms? See Convection

#### Summary

In this class lab activity, students will create convection currents in a plastic container that illustrates how the movement of warm and cold air in the atmosphere creates thunderstorms.

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## Learning Goals

Students will observe and record what happens to warm water and cold water and relate their observations to the water cycle and the creation of clouds and thunderstorms.
Vocabulary:
-Evaporation
-Condensation
-Precipitation
-Convection
-Current

## Context for Use

This activity can be done as a whole class or in partners or small groups, depending on the size of the class. It can easily be done in the classroom. Students should have already studied the parts of the water cycle.

## Description and Teaching Materials

Convection is the transfer of heat by the movement or flow of a substance from one position to another. The purpose of this activity is to see convection.

Colored illustrations, instructions, and opportunities for further study are available at http://eo.ucar.edu/webweather/tornact2.html.

Materials:
-One clear plastic container about the size of a shoebox
-Red food coloring
-Ice cubes made with water dyed with blue food coloring
-Colored pencils
-Index card

Instructions:
1.Fill the plastic container 2/3 full of room temperature water.
2. Let the water sit for 30 seconds or until it is completely still.
3. Place a blue ice cube at one end of the plastic container.
4. Add two drops of red food coloring to the water at the opposite end of the plastic container. Be careful not to disturb the water.
5. Observe where the red and blue food coloring goes.
6.Using the red and blue pencils to draw what you see happening in journals.

Where did the red go?

Water is flowing from one position to another; heat is being transferred; convection is occurring in the container! The cold, blue water sinks, while the warmer, red water rises. The red water stays higher than the blue.

## Teaching Notes and Tips

If available, a good follow-up to this activity is using a convection box, where the movement of warm air is shown by the movement of smoke over a flame and cold air is shown "sinking." Convection boxes are part of the Air and Weather kit of District 279.

## Assessment

Students should show their observations in their science journals. They should be able to articulate that cold air moves downward and pushes up the warm air that rises and the cycle continues as thunderclouds are formed. Students can work in their groups to explain on white boards what convection has to do with making thunderstorms.

## Standards

Grade 4 Earth Science: The student will describe the water cycle involving the processes of
evaporation, condensation, precipitation and collection.