Doesn't your powerful fan cause your temperature to run warmer at night on calm clear still nights though?
Why would that be true?
Thermal dynamics?
Do you have a thermodynamic explanation? Because I can't come up with one. The only possibility could possibly be the fan exhaust getting resucked into the bottom of the FARS like it did with those old ASOS hygrothermometers. I've actually noticed slightly cooler mins due to the faster response time.
I'm not adiabatically mixing the low levels with my little 12V fan. The radiational cooling outside of the sensor chamber remains unchanged...I'm just pulling the air in.
I know meteorologists talk about this all the time. Wind overnight makes it warmer than it otherwise would be with no wind. I believe the term is radiation inversion. It doesn't always happen, but knowing that cold air sinks, you can imagine.
The exact text excerpt I read was:
"A strong radiation inversion occurs when the air near the ground is much colder than the air higher up. Ideal conditions for a strong inversion (and hence, very low nighttime temperatures) exist when the air is calm, the night is long and the air is fairly dry and cloud-free.
A windless night is essential for a strong radiation inversion because a stiff breeze tends to mix the colder air at the surface with the warmer air above. This mixing, along with the cooling of the warmer air as it comes into contact with the cold ground, cause a vertical temperature profile that is almost isothermal (constant temperature) in a layer several meters thick. In the absence of wind, cooler, more dense surface air does not readily mix with the warmer, less dense air above, and the inversion is more strongly developed."