Air refraction as function of TEMPERATURE

Sep 2017
I have been looking for a chart/function but couldnt find.

I need it to do studies on a Schlieren set-up, which relies on the difference of density, thus variations of the air refraction, to make air flow visible.

Hereby I attach a video that explains it better

So, I would appreciate if anybody has such information: Air refraction ~ Temperature (standard Pressure conditions)
Apr 2015
Somerset, England
Surely its not going to be a function of temperature alone?

The humidity will also change with temperature, and this will in turn affect the refractivity.
Jun 2016
I am not sure that there is a significant change of refraction with temperature at standard pressure, however there is a change with density.

Naturally (if pressure is constant) changes in temperature will cause changes in density, but it is the changes in density that are showing on the Schlieren.

So you need to look for the effect of air density on the refractive index;
then look, separately, at the effect of temperature on the air density.
Apr 2015
Somerset, England
My Kaye and Laby publishes refractive index data for air including some formulae for the temperature variation.

They have an online version these days.