I honestly thought* when I saw this that it was how Trump “won” the election, but as probably all my readers already know, Buys Ballot’s law is:
the relation of wind direction with the horizontal pressure distribution named for the Dutch meteorologist C.H.D. (Christophorus Henricus Diedericus**) Buys Ballot, who first stated it in 1857.
It’s a rudimentary method of estimating the position of varying centres of local atmospheric pressure from the prevailing wind direction.
Obvs.
Basically, it works around the relationship that (theoretically) states that the angle between the wind and the pressure gradient is a right angle. That means that in the Northern Hemisphere a person who stands facing away from the wind has high pressure on the right and low pressure on the left; in the Southern Hemisphere, the reverse is true.
We’re in the Southern Hemisphere [checks quickly… yep], so that means that if I stand with my back to the wind, then the low pressure area will be on my left (to be more accurate, it’s actually just slightly forward of my left), and the high pressure area on my right.
But why would I need to know this? Well, I probably wouldn’t, because I’m not a seafarer, miles out in the oceans. And if I did need to know it, then I’d just look at the nearest computer and it would show me where everything was. But in 1857 and for a long time before and afterwards, that wasn’t an option, because the internet was still dial up and that meant that you had to be attached to a really long cable.
Not possible in the middle of the South Atlantic (I am reliably informed).
So this law allowed sailors to estimate where the storm centre was, and thus allowed them to try to avoid it. Of course, you might not have been able to avoid the storm completely, but you could avoid the most dangerous quadrant – that is, the section of the ocean in front of you where the chances of damage from the storm was highest (Northern Hemisphere – front right, Southern Hemisphere – front left).
Less damage in those days (and maybe still even these days) meant more chance of survival.
There are a lot of factors that can mess up the wind/pressure relationship – it doesn’t work near the Equator, for example. But we’re not [checks quickly… nope] near the Equator. And though technology has far outpaced Buys-Ballot and his work, his law obviously still holds true. We just do things differently now.
Next time it’s a bit windy, cancel a marathon give it a go, then impress your friends by comparing your estimates with your modern day synoptic chart.
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* I didn’t, this was just for comedic value.
** Crazy name, crazy guy.