Buys Ballot's Law - Landsman (and Meteorologist) vs Mariner

Perhaps not exactly the burning issue of the day but got curious about it.

Some references say back to the wind and other say face the wind. It’s hard to imagine a mariner going out on the windward bridge wing and tuning his back to the wind. Makes more sense you’d face into the weather.

The Dutchman Buy Ballot and the Americans who first deduced the law stated it as back to the wind.

From Wikipedia:

A version taught to Naval Cadets in WW2 is: “In the Northern Hemisphere, if you turn your back to the wind, the low pressure center will be to your left and somewhat toward the front.” (Aerology for Pilots, McGraw-Hill, 1943, pg 43)

Bowditch uses back to the wind.

Results from Google

Face the wind: 1,430,000 hits
Back to the wind: 2,380,000 hits

From the books here:

Heavy Weather Sailing by K. Adlard Coles
"Obeying Buy’s Ballot’s Law, as Humphrey Barton puts it in his book Vertur XXXV, "Face the wind and the centre of the depression is approximately 100° degrees [90° to 135°] on your right.

American Merchant Seaman’s Manual - No mention of Buys Ballot but instead “Universal rules of the winds” says “standing with back to the wind”

Merchant Marine Officers’ Handbook - Buys Ballot’s Law has it’s own section’s - “Face the wind…”

Meteorology for Seaman by C.R. Burgess - Buys Ballot’s is a footnote - back to the wind

The Oxford Companion to Ships and the Sea call Buys Ballot Law “a rough and ready method of discovering the direction of the centre of a circular storm” - face the wind.

From Bowditch


My own application of Buys Ballot Law (as a mariner with a BS degree in Meteorology) was to face the wind, throw your right arm as far back as it can go, and you’re pointing at the center of the low pressure system. Not sure where I got that from. I’d like to think it was on my own, but it probably wasn’t.

But you seem to be missing a critical distinction in face v. back, that is what direction the low is. For face the wind, it’s to the right, for back to the wind, it’s too the left. Half-full v. half-empty?

Also, you don’t have to go on the wing to know what direction the wind is from. If you’re using this, the sea state will probably tell you the wind direction without going outside,


This is exactly how I learned it, don’t remember where or when. No need to consider the other option of “back to” because I’ve never used it. Better not confuse myself.

This is well understood of course, for a “rough and ready” estimate staying inside is usually going to be good enough. It’s just harder for me to imagine a mariner facing “back to” when outside (or inside either for that matter).

I like going outside from time to time to get the full “feel”. Also sometimes I discover the pilot flag wrapped tightly around the halyards hours after the pilot has disembarked or some such.

That’s how I learned it at Ft. Schuyler. Never heard of the “back to the wind” technique.

I would venture to say, “face to the wind” is thought to be more accurate (due to our face’s sensitivity) than “back to the wind”. That “accuracy” is of course somewhat relative.

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Also need to consider North or South hemisphere of course.

Also, throwing your arm back won’t work if you have your back to the wind and use your left arm. Probably why we learned to face the wind…

I probably didn’t learn it at Ft. Schuyler. Charlie Thor would not have approved of such an easy and practical application. But the MT guys might have learned it there.

Read somewhere “back to the wind” but face to and throw right arm makes more practical sense since your arm can only go so far back which happily matches where the low posit likely be!


David Burch has several posts on the subject:

He uses back to and connects “left” side and “low” pressure.

Screen shot from his video:


I agree the ‘face to the wind’ method is best due to the face’s sensitivity. As intuitive as it appears, some students have trouble with this simple exercise. I’ve often heard head boat passengers declare with great assurance that "the wind just died’ when the boat does a 180 from upwind to downwind.

I never thought to much about it once I was out of the classroom apart from having the cyclonic circulation firmly in my understanding. Back in the day I have had to use the knowledge to avoid typhoons and hurricanes before weather fax machines and decent forecasts were available.

Buy Ballot first stated his law in 1857 and it appeared in Bowditch “before 1900”. Wikipedia doesn’t say exactly when.

In that time period landsman presumably would get wind direction from various source such as weather vanes on barn cupolas and the like. No need to face in any particular direction. Makes a little more sense in stormy weather to put your back to the wind while looking.

At sea it makes more sense to face the wind to determine wind direction.

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I don’t think I’ve ever used the law to determine the location of the center of the low. More to just connect what’s being observed to the weather map. Even then only in the more complex situations where there are multiple lows bouncing about.

Or this situation: If the GPS Fails I’m Riding the Isobars Home

As long as you know right from left either will work

Recalling ‘Meteorology’ with CuNimb Jim at Royal Air Force Navigation School circa 1970, the Buys Ballots Law emerged. Guys were then more concerned with the goings-on above the tropopause and the vagaries of ab initio astro-fixing, so the ‘B-B Law’ morphed into “If you stand with your back to the wind, while keeping low pressure on your left, you know you’re in the Northern Hemisphere”…

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Yes, of course. I never encountered the “back to” until a few years ago. I was surprised when I checked Bowditch to see that they use “back to” as well. It is in fact the correct wording of the law.

This is from David Burch.

These days we see the law with wind on the face and wind on the back, but if we stick to history it is best to use the law with wind on the back.

“Back to” is the more technically correct statement of the law but facing the wind seems more salty.

The OP was a salty vs sciencey comparison of the references I had on hand here.

This rule is, I imagine, more reliable well offshore. As a coastal sailor in the PacNW of the US, I can say that it can get pretty complicated in coastal waters. Particularly on a coast where we have mountains fairly close to shore, because the land topography interacts with the wind and you can see that effect even before an onshore wind makes landfall. Just as light bends to a more “normal” (perpendicular) path as it passes into a denser medium, the wind at the coastline tends to shift to more perpendicular to the coast as it passes inland. And of course, being the E. shore of the N. Pacific, we can get pretty darn complicated low pressure systems coming ashore here. (screen shot of N.E. Pacific @ 0900 GMT 12 June…amazingly like a winter pattern for June!!; but the effect I’m talking about is too local to show on this)

Here’s a zoomed in shot of the S. WA Coast between Grays Harbor & the Col. R. entrance. If the wind arrows show up well enough, I think you can see the WIND REFRACTION AT A COASTLINE beginning to occur offshore of Willapa Bay and continuing into the SW corner of WA.

Not a dramatic shift, maybe 15-20 degrees, but if you’re in a sailboat on a coastwise race like our Oregon Offshore, it can make a difference. If you were trying to sail up the WA coast right now, being close inshore could make the difference between close hauled and a close reach on port tack. Big difference in boat speed.

Another one is the right hand rule, similar to the one in physics.

From here.
The thumb pointing up is a reminder that low pressure leads to rising air. This is a way to remember the low pressure circulation. Low pressure tends to bring in stormier weather.

The advice from the Old Farmer’s Almanac and the like is based on Buy Ballot’s

  • When the wind sets in from points between south and southeast and the barometer falls steadily, a storm is approaching from the west or northwest, and its center will pass near or north of the observer within 12 to 24 hours, with wind shifting to the northwest by way of south and southwest.

I edited the OP to add a graphic from Bowditch.

In the northern hemisphere, if the wind veers (direction of wind changes clockwise SE to SW) the low will pass to your north. If the wind backs (direction of wind changes counter-clockwise SE to NE ) the low will pass to the south.