Measurements of Damping of Temperature Fluctuations in a Tube

Using field measurements we evaluate a previously deduced semi-empirical model for the dampening of temperature fluctuations in a circular tube. The measurements show that the model is a reasonably good approximation, and the previous recommendation of using a tube length of the order of 1,000 times the inner diameter of the tube to remove most of the temperature fluctuations seems to hold. Part of the difference between the empirical results and the model is possibly due to deviations from the idealized conditions assumed in the model such as no inclusion of the influence from the ambient atmospheric stability. Limitations of the measurements are also likely to affect the evaluation.