Hi, I've read the document provided for the topic Sun's Radiation Effect on Two Coolers Placed Under a Parasol at https://www.comsol.com/model/sun-s-radiation-effect-on-two-coolers-placed-under-a-parasol-12825. It has provide a formula " Tamb = Tavg+dTcos(2pi*(x-14)/24)." to define the ambient temperature for a simple 24 hour periodic sinusoidal distribution around an average temperature.
May I know what is the theory behind the formula? why does it use x-14? Please help.