Is there a difference in air pressure between your head and toes?

It has been a lovely day in England today, with highs of 20 degrees (that's 68 F) and a gentle breeze. It has been the sort of weather for relaxing in the sun with a cool drink and a sun hat, and maybe a good book, because it is not often we get the chance to produce some vitamin D in this country. But I couldn't just sit around all day. During the peak of the midday sun, I retreated to the relative safety and coolness of my geek cave and tinkered with my Raspberry Pi Sense Hat data logger.

The 8-by-8 LED matrix on the Sense Hat, which is useful for anything your imagination can conceive. 

The Raspberry Pi Sense Hat data logger uses the brilliant Sense Hat to log temperature, pressure and humidity from its many sensors. You can grab my code from the link above, or read about other Sense Hat projects, and if you have a Raspberry Pi then this is an brilliant add on device that will guarantee hours of fun.

It was this tinkering that made me ponder the question raised in the title of this post.

Is there a difference in air pressure between your head and toes?
Assuming that you have toes on the ends of your feet (as I do), and not growing out of your forehead (as I don't), then there should be a difference in air pressure between these two points due to the difference in height between them (assuming that you are standing vertically). More to the point I wondered whether it was possible to measure this difference. Sadly, Raspberry Pi is not maneuverable enough to lift off my desk (so many things plugged in) which led me to look for barometer apps in the app store.

I soon found Barometr by SeNSSoft for my Lumia 950.

Air pressure at ground level

Air pressure at head height.
And there you have it. The answer is 'Yes', about 0.2 hecopascal (or about 0.1 hecopascal if your name is Frodo).