Rain graph - intensity variation with magnification

Am I misunderstanding the display of the rain graph?
If I use the + / - it appears to me to change the displayed rain intensity. Me or a bug ?

Look at the scale on the left. They are different, most likely due to some earlier days with higher intensity/accumulation of rain.

if you want to have an impression of the rain intensity, the blue bars, you are better of with looking at the “rain-rate” graph. Click on the word “rain” in the lower right of this graph.
In the rain-rate graph the rain rate shares the vertical axis with the accumulated rain. 20 on the axis means both 20mm accumulated and 20mm/hour.
If your are fully zoomed in, each bar is 1 minute. If the bar is at 20mm/hour, it means that the average intensity during that minute would be the same as if it rained 20 mm in one hour. If you start zooming out, the blue bar spans a longer period. That might cause the average intensity during that period to change.
It is confusing and could be made better by using a higher resolution graph. If the graph would show you 600 points instead of 32, it wouldn’t need to do this and could stick to the 1 minute measurements, and when fully zoomed out just get the nearest value, or perhaps the max value.

the graph you showed has the same problem, but rain intensity is put into bins like “very light rain” and “heavy rain”, but it still uses the average and changes with the zoom level.

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The 1st pic at 10am shows 6mm /hr whereas the same day and time (second pic) 26mm/hr.

no, as mentioned that graph just classifies the rain intensities into bins. The vertical scale has no meaning at all for the rain rate in this graph. The lowest value of the bar is always “very light rain”. The scale doesn’t matter.

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