Need help to calibrate my Sense hat thermometer

[/RaspberryPi]

Hi,
I bought a Raspberry pi 3 a while back but decided only recently to add a Sense Hat on it to use it as a home-made weather station. The problem, as some of you may know, is that there is a problem of accuracy with the temperature sensor when the Sense hat is put directly on the Raspberry pi, certainly due to the high temperature of the cpu just below it.
Instead of going the easy way by buying a ribbon and separate the hat from the motherboard (too pity...), I decided to find a mathematical solution instead. The only formula I found on the web ( Part 3. Sense HAT Temperature Correction · initialstate/wunderground-sensehat Wiki · GitHub ) seemed a bit odd to me and so I changed it a bit to be more accurate while still being easy to understand:
Ts = Te + ( Tc - Te ) / L ))
with:
Ts = the temperature from the sensor
Te = the external temperature
Tc = the temperature from the cpu
L = a factor of thermal loss
By modifying that formula, I get the following one to calculate the external temperature from the sense hat:
Te = ( L * Ts - Tc ) / ( L - 1 )
The problem is that the Loss factor (L) that I thought would be constant is not. In fact, it seems like it increase by 0.015 to 0.02 for each additionnal degree of my CPU. So the more it heat, the less my formula is accurate... There must be some missing parameters but I can't find which one and how to make my formula more relevant... Could someone help me with this?
Thanks in advance.

submitted by /u/Danthbyrth
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