Verification of an Equation for Trough and Ridge Motion
A formula for the propagation of trough and ridge lines was tested on synoptic maps. It was found that it works best on the 500-mb chart. At this level the systematic error was found to be small for troughs (< 1 long.° per day) but considerable for ridges (+ 3 to +5 long. ° per day). However, the error scatter was about the same for troughs and ridges. It was found that computations of ridges over elevated terrain such as the Rocky Mountains region have a larger positive systematic error than ridges over flat country. This was not found to be the case for troughs. It is concluded that better results can be expected the closer the actual streamline pattern resembles the model for which the formula was derived.