Use a Atmel ATTINY26
as a serial port based fan controller for a PC. Tracy’s machine is very noisy but has built in sensors for the CPU and case temperature. Use a PC app to do closed loop control on the temperature.
For measuring the vertical temperature gradient cheaply at different stations across about a heactare of land. A heactare is 10000 m^2 or about 100×100 metres. You could use a set of 1-wire temperature sensors in a local cluster.