# Still Water as an Approximate Blackbody

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1. Aug 24, 2015

### ecastro

Can the temperature of a still water be calculated using Planck's Blackbody Radiation? For instance, I have the intensity image of water (of course, this is considered still, as it seems that it is currently stopped in time), and I want to calculate the temperature of the water, is it possible?

Thank you in advance.

2. Aug 24, 2015

### Bystander

https://en.wikipedia.org/wiki/Infrared_thermometer
In principle, given emissivity as a function of wave length and temperature. You might be able to "calibrate" an IR thermometer versus a regular thermometer to do the "heavy lifting;" but, I'd be very suspicious of angle of incidence, container effects, and other interference.

3. Aug 24, 2015

### ecastro

But can I calculate it theoretically?

4. Aug 24, 2015

### Bystander

"Is it theoretically possible to calculate it?" Yes, given emissivity as a function of wavelength and temperature and a long enough path length (deep enough water).