Calculating dispersive path delay due to the atmosphere

I've posted a simple command-line program to compute the dispersive path delay due to the atmosphere using ATM (more precisely my re-packaging AATM). The program is available at:

http://www.mrao.cam.ac.uk/~bn204/alma/aatm-dispersive.html

I had not appreciated that even at 330GHz, the dispersive wet delay is about 10% of the non-dispersive wet delay.