Today we start even later, it finally is now really the weekend. We make our way to UNIS around noon. We want to test and calibrate the new rapid temperature sensor. The measuring element is a 12µm thick platinum wire. This is only about 20x wider than the wavelength of red light.

It is extremely fast due to the low mass and should measure small turbulences (flux) in the atmosphere. Based on two measuring points, the linear characteristic is recorded. We take the first in an anteroom to a climate chamber in which normally ice cores are sawn and examined. The second we get in an even colder climate chamber of biologists.

We then put the sensor, including autopilot and battery in the coffee kitchen fridge and hope for a quick confirmation of our calibration. Far from it.

The fast sensor (red) and the slow reference (green) oscillate around happily. Nevertheless, the reference adapts, albeit slowly. Once we shield the sensors with a cardboard lid, both temperature measurements are quiet. The inside of a fridge is anything but stable. The temperature has leveled out only after about half an hour.