Pedantic: 1 atm = 1.01325 bar (exactly). They're nearly equivalent units, even more so when you consider that Earth's atmosphere varies by more than 1.325% on a given day. But in a strict sense they're not the same.

A variation on the survey foot.

The US survey foot, as you probably know having brought it up but elaborating for the audience, is the old US foot before it was averaged with the British foot to create the international foot. It is 500000/499999 international feet.

I suppose I think a bit differently. I don't know the typical pressure inside a steam engine. However, I do know what one bar, or one pascal means.

I can also guess what ninety atmospheres entails in terms of engineering, because I know that's the pressure at about 900 m water depth (by virtue of the SI units, which are based off water: P = hρg), which few submarines can even reach.

The same thing goes for 'as long as/as big as xxx football fields': which one? American or association? I know what a square metre is, I know what a square kilometre is, just use the damn units.

I really think pop-sci and science education should emphasise standard units (read: SI, not USC) and being able to estimate orders of magnitude.

There's a pedantic comment below (I saw it coming a kilometre away), but why not make life simple and just say 'about 90 atmospheres'?

You don't need to know the typical pressure , but you definitely get the idea the pressure built inside a steam engine is much higher than atm.

The steam pressure is not about the numbers so much but a kind of hyperbole , "you know that thing which hauls tonnes of steel purely on pressure made in a steam boiler , yeah the pressure on Venus is 4 times that pressure "

I found it an interesting fact.

> a kind of hyperbole

I didn’t think of it that way initially, but this makes sense, thanks.

Why reference submarines? What submarines can reach is irrelevant as a comparison when you know a number

Otherwise, it's your reference to submarines that contextualizes the number, same as the insides of a steam engine does for others

> it's your reference to submarines that contextualizes the number

I realised that after the fact. What I meant to say is that standard units should be used, and individuals should be left to contextualise said units of their own accord, instead of it being done for them.

Or both, numbers plus example don’t take much space.