# World HELP

Discussion in 'Earth Science' started by URI, Nov 25, 2006.

1. ### URIIMURegistered Senior Member

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729

What we want is for you to determine the rate of water evaporation from various water sources in your area.

Equipment needed.

(a) Simple digital scales
(b) a few prepared plastic bottles

Method

You will need a few of the same type of plastic drink bottle with a screw cap. These bottles should be clean and rinsed several times in tap water.

Remove the base of each bottle. These bottles are then labled and used to collect water samples. They are weighed before hand (with the screw cap) and after the water sample has been collected, and these weights are recorded along with the Id of the bottle. In this way you can find the weight of water in each bottle.

To collect the water sample, first remove the screw cap, and immerse the whole bottle in the water to be sampled. bring the bottle to the surface of the water with the based uppermost and the screw cap end down. With the base slightly out of the water screw on the bottles cap. Remove the bottle out of the water, dry and label. The here aim is to capture the surface layer on the water intact.

What we will determine is the decrease of the water evaporation rate between clean (no surface film) fresh water and the resident water in your area.

Weight bottle and sample.
Record the weight of water = total weight - bottle weight on a sheet of paper and enter the ID of the bottle and the type of water sample.

Set up the sample bottles in some exposed place where wind and sun can cause the water sample to evaporate. One bottle, called the control, should be filled with tap water (or rain water would give a better baseline).
The bottles with the samples will be upside down, so sit the bottles in wide mouth jars so the sample bottles can be stable when upright.

At 24 hour intervals, record the weight of each bottle.

Calculations

Measure the diameter of the base, and calculate the area.
Let D be the diameter (length from one side of the base to the other side), then the radius of the base is equal to D/2
So the area is (pi times D times D) divided by 4

Next work out the weight of the evaporated water per unit area, that is per square centimeter or per square inch, depending on the units of your length measuring device.

So evaporation rate/ unit area/ day = weight of water evaporated divided by the surface area.

Any questions are welcome.

Once we know what the water evaporation rate is in your area (dams, river, sea etc) compared to clean fresh water we may be able to apply more pressure on the society to clean up its act.

The World thanks you.

Direct results to http://omegafour.com/forum

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729
bump

5. ### phoneticstroking my banjoRegistered Senior Member

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2,157
Won't the bottles fill with rain, skewing the results?

7. ### URIIMURegistered Senior Member

Messages:
729
>> Won't the bottles fill with rain,

not a good idea to leave them in the rain!!, LOL

Clarifications
(a) All samples to be tested should be kept for the duration under the same conditions (sun, wind, shade etc ) but do not leave them in the rain.
It is just as easy to leave all the test cans in a sheltered spot as to leave them in an exposed location. The relative water evaporation rates evaluated will be meaningful.

Any time period is suitable, all we want is the relative water evaporation rates.

(b) The "other" samples that should be tested should be drawn from local surface waters, such as coastal water (sea) lakes and rivers.

The fresh tap water control is used so that the rough results you obtain can be directly correlated with other results obtained.

We just want rough results at this stage, FROM EVERYONE ALL OVER THE WORLD

8. ### URIIMURegistered Senior Member

Messages:
729
Schoolchildren
get you and your friends to do this experiment, it is fun and we might save the Earth.