When water evaporates, it is going to a lesser state, therefore it cools down. So, depending on the amount of evaporation (which is dependent upon the dewpoint), THAT will determine the amount of temp drop.

So now it's up to the small engine guy to figure out a chart that states what the temp change of the pond is in relation to the water temp, ambient temp and dewpoint. wink grin

That's where my brain said TMI to figure out between these ears......... laugh

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