Vertical Lunar Chart, Explained
This chart was designed to highlight the relationship between the Moon and the tide. Specifically, this visualization is meant to highlight the spring tides and the neap tides.
About the data
NOAA makes predicitons for every high tide and low tide for each tide station. The data table has three columns: T, V, and Type. T refers to the predicted time, V to the predicted water level (in feet from bench mark), and Type to the type of tide (high or low). This data comes from NOAA's Tides and Currents Tidal Predictions portal.
| T | V | Type |
|---|---|---|
| 2019-11-08 01:22 | 0.921 | L |
| 2019-11-08 07:53 | 4.668 | H |
| 2019-11-08 14:14 | 1.265 | L |
| 2019-11-08 20:03 | 3.912 | H |
| 2019-11-09 01:54 | 1.132 | L |
| 2019-11-09 08:16 | 4.856 | H |
| 2019-11-09 14:48 | 0.888 | L |
Figure 1: A table showing data from November 8, 2019 and November 9, 2019 showing tidal high/low projections for Moss Landing, Ocean Pier station.
For this chart we also have age of moon data. That comes from the simple version of Ben Daglish Moon Phase Calculators. I use the 'simple' method of moon phase calculation for this visualization.
Making the vertical lunar chart
The vertical lunar chart visualizes the range of tide for each day, as well as that day's age of moon. So to start, we will need to have a spot for each day:
Now we need to add our y-axis. Because we are looking at the predicted range of tide, as opposed to the predicted water level, we will not have any negative values. We can calculate the range of tide for each day by taking the lowest low tide and subtracting it from the high tide.
Now we can add our daily tidal ranges as vertical lines:
Because tide corresponds to the age of the moon, it might be interesting to add the phase of the moon on top of the vertical line for each day's range:
Now we can remove the y axis to get rid of visual clutter:
And voila! The finished chart. Now you can go back to the live vertical lunar chart, or see next chart in the series.