Vertical Chart, Explained

This is the most visually complex chart in the series. It is meant to show how the tides correspond to the lunar dar, which is slightly longer than the solar day, by showing how the time of the predicted high and low tides shift as the Moon ages.

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.

Making the vertical chart

The vertical chart visualizes the range of tide for each day, as well as the time of day for each high tide and low tide. We can start by putting a horizontal line to show the water level bench mark for the Moss Landing station:

The y axis and sea level

Now we can add a line for every day, where the line starts at the highest high tide and ends at the lowest low tide. The range closest to now is on the left, and as they move to the right, they get further into the future:

There is now a line for each day showing the range of tide.

Now we can add each tidal prediction for each day. We can visualize these predictions as circles. Each circle's height corresponds to the predicted water level (V in the table). Each circle is on the line that corresponds to its date (T in the table):

There is now a dot at each data point.

We can sort of see a pattern emerging amongst the circles. We can make the circles a bit bigger, so they are easier to see, and we can also vary the color based on the time of day of the prediction. Dark circles will be predictions that occur between 6 p.m. and 5:59 a.m., and light circles will be predictions that occur between 6 a.m. and 5:59 p.m.:

Now half the dots are light, and half the dots are dark.

Now we can vary the size of the circles depending when the predicted time. Dark dots will peak in size at midnight, and light dots will peak in size at noon:

Now the dots are of varying size

We can add a legend to the chart, and clean it up a bit:

Finished vertical chart

And voila! The finished chart. Now you can go back to the live vertical chart, or see next chart in the series.