|Time Needed:||One 45 minute class period|
|Concepts:||What causes precipitation|
|Purpose:||The purpose of this experiment is to simulate the process whereby the condensed water vapor (cloud) turns into precipitation (rain). Students will use the simulation to construct their own hypothesis of how the precipitation process occurs.|
Students will work in cooperative groups with one student recording information onto the Lab Sheet.Materials for each group:
The teacher will then ask students what happens when a mass of warm air containing water vapor is cooled. (The water vapor in the air condenses onto tiny suspended particles in the air and forms a cloud.)
Now the teacher will ask students to get into groups and come up with a hypothesis to answer the question:
What causes precipitation?
Next the teacher will distribute the materials and explain the directions for the simulation.
Compare your simulation to Earth's water cycle. Which stage of the simulation represented:
Discuss in your group what happened to cause the condensation to turn to precipitation. The condensed water droplets in the cloud (steam) accumulated and increased in size eventually falling back to the surface as precipitation.
Students will discuss their findings and compare their simulation with the natural process. (The sun heats the earth's water causing it to evaporate. The warm air rises and expands. As the warm air rises, the water vapor in the air condenses in the cooler air above and forms a cloud. As the condensed water vapor accumulates, the water droplets grow in size and become too heavy to be contained in the cloud. The water droplets fall to earth as rain or precipitation.
Following the class discussion, groups should record their Concluding Hypothesis, turn in Lab Sheets, and return to their desks.
This experiment adapted from resources provided at http://www-k12.atmos.washington.edu/k12/modules/nw_wx_watch/tchrpg_ex5.html