Guidelines for contouring:

General

1. Use a pencil with a good eraser. Draw the initial lines faintly. Go back over your contours once you are happy with your analysis to thicken and darken them.

2. Remember to draw contours at the specified intervals.

3. Do not draw contours far beyond where there is data.

4. Contours do not fork.

5. Remember to label contours.

6. Values are higher on one side of the contour and lower on the other side.

7. Contours pass through stations that have the same value.

8. Draw contours smoothly.

Rules for drawing isobars

(Isobar: "iso" means "same"; "bar" refers to pressure; therefore an isobar connects points of equal pressure)

1. All points on an isobar have the same pressure. Draw a line through a specific data point only if it has the exact pressure of that isobar.

2. Each isobar has a higher value side and a lower value side.

3. Isobars never cross.

4. Isobars either form closed curves or go off the edge of the map. They don't end in the middle of the map.