Day 5 – Bubble Charts

Rack Top Temp Bubble Chart

Bubble charts visualization takes accuracy to the next level because they can show three variables at one time.  In this case the parameters are rack, top temperature, and time. Each vertical line is a specific rack.  The graph above is displaying the top temperatures.  The bubbles on that vertical line represent the temperature of the rack during the time period (the temperatures are rounded to the closest 2°F increment).  The size of the bubble indicates how long the rack was at that temperature.  For example: the top temperatures at rack 6 were roughly 68°F, 70°F, 72°F, 74°F, and 76°F.  The larger bubbles at 72°F and 74°F indicates that rack is operating at those temperatures the majority of the time.


  • It is instantly obvious that racks 12, 17, and 20 have persistent hot spots.
  • There appears to be multiple racks that share the same temperature profile.  Racks 1 – 4 are all operating in the same temperature range.  Racks 5 – 10 are also similar.
  • Rack 15 seems to be an outlier operating cooler than its surrounding sensors.  Possibly an airflow issue?
  • Racks 31 – 34 are the coldest of the bunch.  There may be an excessive amount of floor tiles in this region.


  • Bubble charts can only show one measured parameter at a time. In this case, it represents rack top temperatures .Bubble charts are not good for comparing rack top and rack bottom temperatures
  • Also, bubble charts should be reviewed over a specific time duration.   The chart above displays data over the course of a week.  You could certainly look at data over the course of a month or longer, but it becomes more  difficult if you would like to compare two time periods such as one week versus another week.

Previous Posts
About the Data
Day 1 – From 10,000 Feet
Day 2 – Rack by Rack
Day 3 – Learn to Love Graphs
Day 4 – Wordle
Today – Bubble Charts
Tomorrow – Bubble Charts Delta

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