The scrolling charts below represent the HDF channel, one of the two sensor channels coming from my Raspberry Pi Shake & Boom. They display differences in micro-barometric pressure in units of Pascal (Pa) in real time.

In a similar way to the seismometer, the upper trace is the actual raw data and the lower trace a waterfall plot in real time. The vertical axis, in this case, is in units of Pascals (or Newtons per square metre). The Pascal (Pa) is the official SI unit of pressure. One “Standard Atmosphere” of pressure is defined as 101,325 Pa by the IUPAC, the International Union of Pure and Applied Chemistry.

This live stream, under “quiet” conditions, exhibits very small pressure differences (due to infrasound changes) of the order of 0 to 1 Pa. This is extremely low when we consider that a change in the weather of 1 millibar barometric pressure is equal to 100 Pascals.

If there is a sudden change in “micro-pressure” such as from a passing helicopter, a large meteor, military jet or some nuclear or other sub-surface explosion, this will register as a much larger signal from the background level.

The horizontal axis is time over the last 5 minutes or so. 

So if ever you are browsing this page and happen to see a large increase in signal intensity I would be happy to receive your comments post hoc.

Thanks!

Steve