Grobhead - Buys Ballot's Law only applies at the surface. As Steve says, at altitude it would apply to temperature rather than pressure system. His example of the jetstream is very instructive. Imagine the wind is a low-level jet. If coming from the left, the aircraft is flying towards the cold sector, so the temperature is reducing. From what my students have said, his CD is good.
Also, as explained at constant flight level there is no particular reason for a change in temperature due to change in altitude.
Steve - glad I got it right! Over 4 years since I sat Met.
Last edited by Send Clowns; 10th June 2005 at 11:48.