In this really cool science experiment we will learn about the water cycle and the role of plants and trees
in it. In the process we will learn about transpiration, precipitation, and evaporation. Plants put down
roots into the soil to draw water and nutrients up into the stems and leaves. Some of this water is
returned to the air by invisible transpiration. Transpiration rates vary widely depending on weather
conditions, such as temperature, humidity, sunlight availability and intensity, precipitation, soil type and
saturation, wind, land slope. In this experiment we will make the invisible both visible and measurable!!
Materials For Water Cycle Transpiration Experiment
- Medium to Large Clear Plastic Bag (the more clear the better!)
- Some String
- Measuring Cup
Process For Water Cycle Transpiration Experiment
1) Start first thing in the AM before sun is really out strong. This experiment works best on sunny hot
2) Make a hypothesis about how much water you think you will capture in your bag through transpiration.
3) Lay out your clear plastic bag, string, and scissors,
4) Cut off about a foot of string.
5) Go to your yard and find yourself a nice green plant or tree, Something with big green leaves!
6) Stuff as much green leaves of the plant or tree into your plastic bag. Don't break off the vines, stems,
or branches - leave them attached.
7) As tightly as you can use the string to tie the open part of your plastic bag closed around the
branches, vines, or stems. The goal is an air tight bag.
8) Go check your bag every hour to see the changes. Document the results.
9) Let it sit until the sun goes down.
10) Remove the string from the bag. Without spilling take your bag inside and use the measuring cup to
see how much water you captured from plan transpiration.
The Science Behind Plant Transpiration Experiment
- Condensation builds in the clouds. Water precipitation falls to Earths surface in the form of rain
and snow. This water infiltrates the beneath the ground and also falls or runs into oceans, rivers,
and streams. Some of this water evaporates back into the air which makes its way back up into
the clouds to condense again. Note: Condensation is the change of the physical state of matter
from gaseous phase into liquid phase and is the reverse of vaporization. Precipitation is any
product of the condensation of atmospheric water vapor that falls under gravity.
- Some of the water that infiltrates beneath the surface makes it's way back up to the clouds via the
plants and trees. This process is called transpiration. Transpiration is the process by which
moisture is carried through plants from roots to small pores on the underside of leaves, where it
changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of
water from plant leaves.
- Studies have revealed that about 10 percent of the moisture found in the atmosphere is released
by plants through transpiration.
- One neat thing about transpiration and evaporation is that it is invisible to us. We cant usually
see it happening. However the science experiment above, we will make it visible and
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