Late Friday evening (Iowa time), a massive volcanic eruption happened near Tongo, a place north and east of New Zealand. The eruption generated a shock wave / sonic waves in the air that have continued to transverse the globe up until at least the time of this writing. Like waves you see in water, these waves create vertical displacements of air causing surface air pressure fluctuations. The featured movie presents an animation of minute interval pressure data observed from NWS/FAA ASOS stations. The data is presented in the form of "sparklines". Each line represents the map location of an observation time series lasting 15 minutes. The north/south variation in the line represents a change in pressure with the color being the magnitude over the 15 minutes. As you play the movie, you can at least readily notice the propagation of the wave across the country. Others on the Internet have computed this wave to be traveling at approximately the speed of sound! There are many other nuances that can be seen in the plot, including many smaller waves coming after the first wave. So, do you know what is even crazier? There was another wave transversal earlier this Sunday morning from east to west as the initial wave from Tonga made its way east around the globe and arrived at the USA. The one minute data is not available from it yet, so check back later for another lapse from it.

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Tags:   tonga   volcano   pressure