The next, and last, step in our study of the correlation of the various weather elements concerns the sequence of weather changes at a station before, during, and after the passage of a cyclone and of an anticyclone.

A. Cyclones.—I. Select some station which the weather maps show to have been directly on the track of a well-developed cyclone, i.e., to have been passed over by the center of the cyclone. Note the weather conditions at this station, before, during, and after the passage of the storm. Tabulate your observations according to the following scheme:—

Weather Changes at ________________________ during ______________.

In the last column of the table enter the direction and the distance of the cyclonic center from the station, at each observation.

II. Select a station which was north of the track of a cyclone, and tabulate (in a separate table) the weather conditions at that station before, during, and after the passage of the center.

III. Do the same for a station which was south of the track of a cyclone. Repeat these observations for several stations.

B. Anticyclones.—Make a similar series of observations for the passage of an anticyclone centrally over, north and south of, several stations.

Study the sequence of the weather changes shown in the various tables. Deduce a general rule for these changes and write it out.