the water cycle

Since its beginning, the earth had only a certain amount of water. Those water molecules have been used and re-used, cycled and recycled, over and over again. They have been drunk by every animal, used by every plant, evaporated countless times, come down again as rain, snow, sleet and hail, then through the same cycles again and again. You will see all three parts of the water cycle in this activity. 

MATERIALS: a hot plate or burner and stand; small beaker-150 or 250ml; Watch glass; ice cube

HOW TO DO IT: Put 1-2 cm of water into the beaker and put it over the heat to boil it. Put the watch glass over the beaker and put an ice cube on the watch glass.

When the water boils, the stream will rise to the cold watch glass and condense into water droplets. They eventually will fall back down again. The Inside of the beaker in analogous to the earth's atmosphere. The heat source is like the sun. The heat evaporates the water. The ice cube simulates the cold temperatures at higer altitudes which condense the vapor into droplets.