56 ms·

I thought these crazy Americans wouldn't surprise me anymore with another strange unit of measurement and here's the acrefoot

by dsab 3y ago

artursapek 3y ago
[flagged]
- flangola7 3y ago
  [flagged]
epistasis 3y ago
Using awkward units of measurement that have little compatibility results in a multiplication of even more awkward units. If you don't have a good, easy way to convert between acres and square feet, you instead need to imagine some unit custom built for the application. So rainfall is typically measured in inches, crop areas in acres, simple we will just invent an acre-foot and now people can convert their rainfall needs into water amounts. Maybe. There's probably a lesson for system design here.
codyb 3y ago
Seems fairly intuitive? Width and length of an acre with a depth of a foot
- petschge 3y ago
  until you try to convert to (millions of) gallons.
  - kevinpet 3y ago
    Ah yes, since we all have an intuitive grasp of what millions of gallons, and can visualize what that means over however many 40 acre farms.
    - epistasis 3y ago
      But your equipment for handling water is almost certainly going to measure things in terms of volume/minute, where the volume unit will not be acre-feet. Perhaps it's gallons. Or hogsheads. The acre-foot is a useful measure only for certain scales of volumes, but there's a need to convert between small and large scales of volumes all the time. If we didn't have the metric system, sure, the acre-foot makes sense to use. And in the metric system, perhaps people will occasionally talk in terms of hectare-cm instead of liters or m^3 (I don't know enough about non-US water systems to know what they typically use). But regardless of liters or m^3 or hectare-cm, these can all be converted by moving a decimal point rather than multiplication or division with multiple significant figures. We have a better system, we have just chosen not to use it.
amalcon 3y ago
"Volume that can flood a defined area A to depth B" isn't a totally unreasonable way to measure large volumes of liquids that are replenished by falling from the sky over an area. Of course it's a bit odd because it uses acres and feet for the area and depth, instead of reasonable units like meters, but those are just the usual strange units.
- epistasis 3y ago
  The point is that because our unit of area, the acre, has a very difficult conversion from our units for length, and there are even extremely difficult conversions for different scales of length, we invest yet another unit. Whereas in a more rational system, the unit for volume would be based on the unit for length in such a way that one could easily convert square-kilometer-inches into cubic meters without a calculator, for example.
  - amalcon 3y ago
    I would contend that in the context of reporting specifically on a water shortage, a unit like km^2*cm is actually superior to m^3. First of all, that conversion is actually nontrivial to do in your head. Yes, it's easy enough if you're focused on it it (factor of 10,000). Someone who doesn't frequently convert volumes could easily have an off-by-1000 error while casually reading an article. This is a kind of error that science teachers see all the time. Second, the direct "depth of flooding" value is useful both on the production side (rainfall) and for two of the largest consumers (agriculture and lawn care). The conversion therefore needs to happen twice, which is one of the usual thresholds for delaying the conversion into M-K-S.
electroly 3y ago
To be fair it's really just an application of the same strange units. Once you've committed to acres for land and feet+inches for rainfall, acrefeet is the only option you've really got for volume of rainfall. We have to fix land (square kilometers) and rainfall (millimeters) before we can fix volume of rainfall (cubic meters).
VoodooJuJu 3y ago
It's not strange. It's an emergent domain-specific measurement that means something to practitioners within that domain. What's strange is chopping off the head of a bunch of French aristocrats because ergot poisoning drove you mad, and then replacing old emergent domain-specific measurements with something new because those old measurements just aren't rational, and you're clearly very rational, obviously, because what could be more rational than tearing a bunch of people from their homes and chopping off their heads? Their world order was clearly arbitrary and irrational, and evil! So with that oppressive old world order extinguished, you're now impelled to conjure new, more rational unit definitions like "one ten-millionth of the shortest distance from the North Pole to the equator passing through Paris", which is in no way arbitrary, and is of course very rational and sensible. And from this day henceforth, the ploughman shall no longer measure his land in terms of the area that a pair of oxen can plow in a day (1 acre), but in terms of the square of "one ten-millionth of the shortest distance from the North Pole to the equator passing through Paris" - the meter! The meter is rational, scientific, even noble, yes indeed.
rqtwteye 3y ago
It could be worse. Schoolbustenniscourt comes to mind. Or footballfieldgiraffe
mywittyname 3y ago
It's typical to measure large surface areas in acres and the depth of water in a foot. So this seems like a very appropriate unit of measurement. An acre of water a foot deep. It makes thinking about large volumes of water easier - especially in the context of lakes and rivers. I have no clue how to begin thinking about 5,000,000,000 kiloliters or 130,000,000 gallons. But I can visualize an acre, and I can visualize a foot. Plus, think about rates of change. If 5 acre-foot of water is moving through a channel every hour, and you have a 500 acres reservoire, then the water level drops by 3 inches a day.

I thought these crazy Americans wouldn't surprise me anymore with another strange unit of measurement and here's the acrefoot

by dsab 3y ago

I thought these crazy Americans wouldn't surprise me anymore with another strange unit of measurement and here's the acrefoot

artursapek 3y ago

[flagged]

flangola7 3y ago
[flagged]

epistasis 3y ago

Using awkward units of measurement that have little compatibility results in a multiplication of even more awkward units. If you don't have a good, easy way to convert between acres and square feet, you instead need to imagine some unit custom built for the application. So rainfall is typically measured in inches, crop areas in acres, simple we will just invent an acre-foot and now people can convert their rainfall needs into water amounts. Maybe. There's probably a lesson for system design here.

codyb 3y ago

Seems fairly intuitive? Width and length of an acre with a depth of a foot

petschge 3y ago
until you try to convert to (millions of) gallons.
- kevinpet 3y ago
  Ah yes, since we all have an intuitive grasp of what millions of gallons, and can visualize what that means over however many 40 acre farms.
  - epistasis 3y ago
    But your equipment for handling water is almost certainly going to measure things in terms of volume/minute, where the volume unit will not be acre-feet. Perhaps it's gallons. Or hogsheads. The acre-foot is a useful measure only for certain scales of volumes, but there's a need to convert between small and large scales of volumes all the time. If we didn't have the metric system, sure, the acre-foot makes sense to use. And in the metric system, perhaps people will occasionally talk in terms of hectare-cm instead of liters or m^3 (I don't know enough about non-US water systems to know what they typically use). But regardless of liters or m^3 or hectare-cm, these can all be converted by moving a decimal point rather than multiplication or division with multiple significant figures. We have a better system, we have just chosen not to use it.

amalcon 3y ago

"Volume that can flood a defined area A to depth B" isn't a totally unreasonable way to measure large volumes of liquids that are replenished by falling from the sky over an area. Of course it's a bit odd because it uses acres and feet for the area and depth, instead of reasonable units like meters, but those are just the usual strange units.

epistasis 3y ago
The point is that because our unit of area, the acre, has a very difficult conversion from our units for length, and there are even extremely difficult conversions for different scales of length, we invest yet another unit. Whereas in a more rational system, the unit for volume would be based on the unit for length in such a way that one could easily convert square-kilometer-inches into cubic meters without a calculator, for example.
- amalcon 3y ago
  I would contend that in the context of reporting specifically on a water shortage, a unit like km^2*cm is actually superior to m^3. First of all, that conversion is actually nontrivial to do in your head. Yes, it's easy enough if you're focused on it it (factor of 10,000). Someone who doesn't frequently convert volumes could easily have an off-by-1000 error while casually reading an article. This is a kind of error that science teachers see all the time. Second, the direct "depth of flooding" value is useful both on the production side (rainfall) and for two of the largest consumers (agriculture and lawn care). The conversion therefore needs to happen twice, which is one of the usual thresholds for delaying the conversion into M-K-S.

electroly 3y ago

To be fair it's really just an application of the same strange units. Once you've committed to acres for land and feet+inches for rainfall, acrefeet is the only option you've really got for volume of rainfall. We have to fix land (square kilometers) and rainfall (millimeters) before we can fix volume of rainfall (cubic meters).

VoodooJuJu 3y ago

It's not strange. It's an emergent domain-specific measurement that means something to practitioners within that domain. What's strange is chopping off the head of a bunch of French aristocrats because ergot poisoning drove you mad, and then replacing old emergent domain-specific measurements with something new because those old measurements just aren't rational, and you're clearly very rational, obviously, because what could be more rational than tearing a bunch of people from their homes and chopping off their heads? Their world order was clearly arbitrary and irrational, and evil! So with that oppressive old world order extinguished, you're now impelled to conjure new, more rational unit definitions like "one ten-millionth of the shortest distance from the North Pole to the equator passing through Paris", which is in no way arbitrary, and is of course very rational and sensible. And from this day henceforth, the ploughman shall no longer measure his land in terms of the area that a pair of oxen can plow in a day (1 acre), but in terms of the square of "one ten-millionth of the shortest distance from the North Pole to the equator passing through Paris" - the meter! The meter is rational, scientific, even noble, yes indeed.

rqtwteye 3y ago

It could be worse. Schoolbustenniscourt comes to mind. Or footballfieldgiraffe

mywittyname 3y ago

It's typical to measure large surface areas in acres and the depth of water in a foot. So this seems like a very appropriate unit of measurement. An acre of water a foot deep. It makes thinking about large volumes of water easier - especially in the context of lakes and rivers. I have no clue how to begin thinking about 5,000,000,000 kiloliters or 130,000,000 gallons. But I can visualize an acre, and I can visualize a foot. Plus, think about rates of change. If 5 acre-foot of water is moving through a channel every hour, and you have a 500 acres reservoire, then the water level drops by 3 inches a day.