Air temperature and water temperature

[pep10]

hey guys,

if I've got a given body of water and i know the air temperature above it, does anyone know how i might go about calculating the temperature of the water? surely there must be an equation or two that converts between the two bodies... any help would be gratefully received!

many thanks, pep10

 

[nasu]

You need to be a lot more specific. With what you said so far, the temperature of water can be any value. There is no conversion formula as such.

For one thing, when you say "body of water" you mean something like a lake?
If this is the case, you can have different water temperatures for the same air temperatures, and viceversa. For example, you can have air temperature 20 C in the summer, with water temperature about the same and you can have air temperature 20 C at the end of the winter, with the water still frozen.

 

[pep10]

ok many thanks nasu... well I'm thinking in particular about stagnant bodies of water, perhaps fairly small, where maybe mosquitoes might breed. if I've got some time series data on air surface temperature in a particular region containing these bodies of water, I'm interested to know how these air temperatures might translate into the temperature of the stagnant water, since the development rate of aquatic mosquitoes depends crucially on this...

does that help?

 

[russ_watters]

Air conditions can vary greatly, but typically the water should be about equal to the average wet bulb temp.

 

[Integral]

Obtaining a temperature is never easy. To get a meaningful result you need good knowledge of the total energy exchange with the environment. In your case the air temperature is just a part of this exchange. You would also need to have information on ground temperature. Even then there will be unknown factors in the energy exchange which would make any calculations approximate at the best.

So the quick answer is, no there is no simple mathematical formula which will give you the answer you are looking for.

 

[nasu]

ok many thanks nasu... well I'm thinking in particular about stagnant bodies of water, perhaps fairly small, where maybe mosquitoes might breed. if I've got some time series data on air surface temperature in a particular region containing these bodies of water, I'm interested to know how these air temperatures might translate into the temperature of the stagnant water, since the development rate of aquatic mosquitoes depends crucially on this...

does that help?

It does help my understanding of your question.
Unfortunately, as other posters have already mentioned, there is no "translation" between the two temperatures.
Even if you take a series of measurements of both air and water temperatures over a period of time, I suspect that it will be difficult to find a simple correlation. The temperature of the water at any given moment depends not only on the temperature of the air at the same given moment but also somehow will depend on the (recent) history of the temperatures.
You may find some regularity and be able to predict water temperature, within some limits.