On Wed, 01 Sep 2004 13:41:14 +0000, dr-solo wrote:


running waterfall drops temp if air temp is lower than water temp.

Ok,

I talked to my 60+ year old physcist (spelling?) and learned a lot about
water flow. It's very complicated, but I will try to condense down what I
learned. From our conversation, I believe the above statement is false.
Here's why:

when water flows down a waterfall it has some amount of kentic energy
(provided realistically by the pump) this kentic energy in one way or
another is turned into heat. Let's assume for a moment 100% humidity,
then there would be no lose of water or energy due to evaporation. This
means all that KE is passed to the water, warming it up. On the flip side
of this is 0% humidity where almost all the energy will be used in
evaporation. Now the amount of KE is dependant upon the height of the
waterfall or the energy provided by the pump (minus friction and other
fluid loses). Thus it could be assumed that the larger the pump, the more
energy the waterfall *could* pass to the pond, given a high humidity. Now
what does this have to do with the outside tempature... Well if the
amount of energy necessary to drop the water temp is less than the
amount of energy being imparted to the water than there would be a
net gain of heat in the pond.

What does this all mean? From our conversation -- it is possible that
given the right circumstances that a pump ***COULD** (not saying WILL)
increase the temp in a pond.

Again this would mean a pump that in imparting greater energy to water
flow (minus friction and the such) than is being removed by evaporation
and tempature cooling could increase a ponds tempature.


"Nathan A. Smith" wrote:
1. To run the waterfall or to not run the waterfall...
2. When to stop feeding...


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