Evaporation Rates

Most recent answer: 06/30/2011

Q:
I have placed a 5 gallon plastic bucket suspended by a styrofoam flotation collar into a 125 foot diameter concrete tank. Both bucket and tank are filled with water. The tank and bucket have no cover or obstruction and are exposed to identical environmental conditions. If the bucket is my control and the tank is my unknown would I experience the same rate of evaporation in both vessels? ie: 1/2" loss in both assuming zero leakage in the larger concrete tank or is the leakage in any way proportional to the exposed surface areas of each vessel?
- Chris (age 53)
Centreville, VA USA
A:
I can make a guess, and would be interested in what you find. Evaporation requires heat. Out in the big tank there are probably some convective rolls in the water, keeping the heat stirred up. Your bucket is partly insulated from that. My guess is that the evaporation from it will be a bit slower. Of course, if the whole thing is exposed to sunlight or otherwise heated from above, the opposite effect might show up.

Mike W.

(published on 06/30/2011)