Rules of Isoplething

  1. Never violate a valid data point. Only in extreme and defendable circumstances should data be omitted. Analyze for all given data.
  2. Interpolate as much as possible. Allow for extreme packing of isolines if that is defendable.
  3. Smooth isolines and, whenever possible, keep pacing consistent.
  4. Do not analyze for what does not exist. Do not assume data.
  5. There should be no features smaller than the distance between data points.
  6. Isolines cannot intersect nor can they suddenly stop. Just as data is continuous, so are isolines. The exception to this is naturally at the end of a page.
  7. Label all closed isolines with appropriate markings (i.e. "H" or "L") in bold and large letters. Label the maximum and minimum values with a small underline.
  8. Label the ends of the lines neatly and consistently. Make sure that any abbreviations are understandable. Title the map and include time.
  9. Analyze in even multiples of the interval of analysis.
  10. Remember that each line must represent all areas with the specified value. On one side of the line, values will be lower than the value on the line and on the other side, values will be higher.
  11. Use a good pencil and initially sketch lines lightly. If needed, make them smooth by darkening the lines after you know where they should be placed.
  12. Have a good eraser handy.
  13. Start with a line that gives you a good understanding of what is happening. This may be in the middle or near the extremes. Use this line as a guide to draw the rest of the isolines.
  14. When the lines become tricky to draw, consider all the alternatives. There may be a better way to draw the analysis.
  15. Remember that the data is only a reflection of the actual atmosphere!