Yesterday I was out walking in Bucharest, and got an emergency warning on my phone, saying that there could be heavy rainfall : “25 l / sqm”. I am aware that weather forecasts use the “litru pe metru pătrat” unit of measurement, which as a unit is equivalent to just mm in the SI system ( http://www.meteo.md/index.php/clima/terminologie-si-unitati-de-masura/unitati-de-masura-si-corelatia-lor/ ) – But it seems a bit convoluted, it does not roll off the tongue more easily, nor produce a clearer mental image of what is being conveyed. At least to me. So I am curious to hear any reason why l / m^2 would be a preferable unit.
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I’m Romanian and don’t know it either. I just learned that 60l/M2 is a lot and 20l/M2 is not so much, so I got used to it and know what to expect
1 L/m² = 1 mm
You can express it either in mm or l/m², they are equivalent.
Imagine one buchet with water in one meter square aka a square with sides long as 1 meter
https://en.wikipedia.org/wiki/SI_derived_unit
Not everyone is as smart as you. Most people don’t know that liters can be converted to meters
Because the litre expresses the volume of the water, which is more relevant in this context
I personally think of it as an emphasize on the volume of water that hits a surface of 1m^2, as opposed to mm that, for me, is not immediately linked to water. I guess it’s easier to visualize for some people, myself included, like having a hole of 1m^2 and pouring, say, 40l in it.
Un metru cub = 1000 litri
Metru pătrat este aria cubului.
Deci a plouat 1 mc/50 pe o arie de 1 mp
Acum tb sa vizualizezi 😁
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> So I am curious to hear any reason why l / m2 would be a preferable unit.
Easier for people to understand.
It’s because you’re comparing a simplified contraction of an unit of measurement (mm of rain) to a another unit of measurement named in it’s (nearly) full form (l/m²).
Millimeter of rain is actually a layman’s term which when laid out would be something like cubic millimeter per square millimeter and since cubic millimeters are directly related to liters and square millimeters to square meters, you saying “mm of rain” would be like us saying liters of rain (without explicitly mentioning the m²) – which is something that people actually use a lot here as well.
Also, there’s another component of measuring rain that’s usually omitted when talking about it and that is time – the amount of rain that we measure is actually always taken in relation to a time frame (yearly, monthly, daily and so on, or specific rain event or sensor sampling rate).
So, in conclusion, a complete description for a “unit of rain” would be a unit of volume over a unit of area during a unit of time. You use simply the unit of volume (as do we usually – “A plouat 60j de litri”), while the local authorities usually report in unit of volume over unit of area.
Regardless, I’d say that working with liters is superior to mm in a few key areas such as agriculture where you also apply other stuff that’s usually measured in liters and not cubic mm (irrigation, fertilization, pesticides etc.), but I kinda agree with you on the redundancy of always reminding people that we’re talking about a square meters.
Trust me, even Romanians don’t know how a liter of liquid on a square meter looks like. It’s just something authorities use because there is no other way to say it.
Because agriculture standards, I guess. That information it’s not that useful for the usual pleb, but for people involved into agriculture.
There are some calculations that can help the people involved into wheat farming, what to expect on the yield side, based on the quantity of rain from a certain period of growth.
Profit margins are tight, so you have to be aware of all the conditions, otherwise you’re going to get bankrupt.
LE: This rain quantity information is used also by hydrologists to check if a flood can be expected on river basins. That’s a serious shit and if you don’t make the calculations as close to reality as possible, people will die, houses are going to be destroyed, businesses as well, etc.
First of all I’ll be a bit pedantic, mm is not SI, m is.
Second of all I don’t think I agree with l/m^2 not paiting a cleare mental image. It’s volume divided by area, which while it is lenght, it’s a more clear type of lenght in my opinion, which is height. Also the base idea is that on average X amount of volume of water will rain over Y amount of area, not that we will have Z height of water, which because of drainage will not be true anyway.
The reason certain systems might seem more convoluted will also be related to what we’re familiar with, compared to what is actually convoluted.
Because it makes sense ? Volume over area. All the information is there, right in the message.
A bucket has 10 liters or ~~2.5 gallons , 1 square meter is = ~~1 square yard so imagine buckets on a 1/1 meter or 1/1 yard . You’re welcome everybody
Edit :added gallons and yards
Considering that Romanians are taught how to convert units before highschool, why would it bother you?
Don’t you think it’s silly to measure water, a liquid, using a length unit (meters) instead of the volume unit (m^3)? It is normalized to a given surface (m^2) to indicate the severity of the rainfall, since there was also a time interval for which the alert was given.
Yes, simplified, the ratio results in a height of water of some mm and it can be indicative of how tall the column of water would get if the water would not infiltrate into the ground, but it is not how water is measured. Again, in a given time interval.
For me it’s interesting to know why you think it would be better to express the expected water volume in a non-scientific way. Except from oversimplifying and not giving positive examples of how science can be used in a domestic setting. And dumbing everyone down not to know how water is measured.
Yes indeed! I always ask for 0.3 mm / sqm or 0.5 mm / sqm of beer when I buy a bottle of beer!
Believe it or not, the rain water is taxed and included in the monthly water bill by the water/sewage companies.
It makes more sense, like it’s logical :3