After the students responses, tell them that it looks sort of like a tornado. Ask students if they know some places that have several tornados a year. Instruct students that the prairies get a lot of tornados. Instruct students that they get a lot of thunderstorms which produce tornados. Thunderstorms are caused from water on the ground being evaporated, or water in a gas form going into the air caused by heat, and then forming clouds full of rain.
Air carrying precipitation, or water in the clouds, also comes from the Gulf of Mexico.
Point out on the map of United States where the Gulf of Mexico is. Tell the students that the prairies get a total rainfall of six to twenty-four inches a year. Tell students what the local rainfall is and compare with six to twenty-four inches a year. Choose a student to measure vertically six inches with the ruler on the chalkboard. Have the student draw a line showing six inches with the chalk.