Is warmth/temperature sensed linearly or on a different scale?
The human sensation of warmth is not the measurement of static temperature.  Humans detect the rate at which heat is leaving (or entering) their body.  For instance, if you are sitting in your 0 degree car in the morning, your hand in the open air will feels warmer than your hand touching the steering wheel, despite them both being at 0 degrees.
The reason is that heat conduction from your hand to the steering wheel is much faster than convective heat transfer from the air.  So you feel &quot;colder&quot; touching the steering wheel, but it's really that you're losing heat faster.
Scholarpedia's article on temperature receptors:
http://www.scholarpedia.org/article/Thermal_touch#Temperature_receptors

...Cold receptors respond to decreases in skin temperature over a range
of 5-43 °C...
...In contrast, warm receptors signal that skin temperature has
increased...