Carrion Luggage

It Fell from the Sky

Here's a potentially misleading headline from PopSci.

    There are actually 9 types of precipitation  
It’s more complicated than just rain, sleet, and snow.

There's a persistent myth that's been floating around for as long as I can remember that the Inuit have multiple (the actual number changes and is ultimately irrelevant) words for snow. This is at best a misunderstanding,   and doesn't take into account that where English uses an adjective + noun formation, the language in question uses a noun+suffix formation, where the suffix functions as an adjective.

Or so the Wiki link there says, anyway. Regardless, my point is that this study of precipitation seems to result in nine names for precipitation rather than the common three.

Most of us generally think of precipitation in terms of three varieties: rain, snow, and sleet.

Well, okay, but there's also hail. And frogs and dust and bird poo and locusts, but I'm willing to limit this discussion to some type of water falling from the sky.

Which leads me to the simplest way to describe precipitation: water falling from the sky. It's a legitimate point of view to note that rain, sleet, snow, and hail are all forms of water.

It's probably not very helpful, though. Even in hydrology, you need to know whether the water falls as snow and melts slowly (or not at all), or as rain and runs off quickly.

The next obvious possible categorization, then is: liquid or solid? This lumps sleet and snow into the same category, which, as far as I'm concerned, is absolutely fair. And it implicitly includes hail.

What I'm getting at here is that this starts to look less like science and more like purely human definition. Like how big is a pebble? A rock? A boulder? The dividing lines are kind of arbitrary. Or how a planet is defined. Or hills vs. mountains, or oceans vs. seas.

In fact, a team of researchers including NASA engineers spent almost a decade analyzing weather data to fine-tune these categories.

Now, I am not saying this was a waste of resources. There are, as the article notes, good reasons to categorize things as they did. All I'm saying is that a different team of researchers, perhaps in a different country, could very well have come up with different categories.

As they explained in a study recently published in the journal Science Advances, they aren’t trying to nitpick—they’re hoping to save lives.

Another "categorization" example is the hurricane scale. It is, as far as I know, based on sustained wind speed. But the cutoffs are somewhat arbitrary. For example, look at Category 2 on the scale, here.   Wind speeds for that category are given in mph, knots, and km/h: 96-110, 83-95, and 154-177, respectively.

One can tell at a glance that the Saffir-Simpson scale is American in origin, because it's based primarily on miles per hour. If a more civilized country had produced it, perhaps Cat 2 would have been 155-174 km/h. In practice, there's little difference between that and the current Cat 2 definition, but it does give primacy to SI units rather than Imperial ones. And this isn't even getting into how that scale may not be adequate for risk assessment.

The headline article also gives a temperature range in Fahrenheit. So, yeah, definitely US.

It’s understandable to think that snow only enters a forecast when the temperature drops below freezing, but that’s actually not the case for meteorologists.

Temperature changes with altitude, so no, I don't find it all that understandable to think that.

The article describes the methods they used to record ground-level precipitation, and they're interesting, but I don't really have any comments on them. Except for this bit:

To start, they installed a specially designed camera array from NASA called the Precipitation Imaging Package (PIP) at seven strategic sites across the United States, Canada, and Europe.

I feel like the sample size here should be questioned. While pretty much the entire world experiences precipitation—even Antarctica and the Atacama desert, to a very small extent—the patterns are different everywhere, and, moreover, the bulk of the world's population lives in Asia. If you're going to make categories based on how people are affected, maybe take into account the majority of the people?

So, what are the nine technical categories to be on the lookout for this fall and winter?

Oh, yeah, and they left out the entire southern hemisphere.

You can read these categories at the link; what they are determined to be may be important to know, but irrelevant to the point I'm making here.

Which is that ultimately, categorization, while sometimes useful, is a human activity subject to human biases.

Also that frozen precipitation of any kind sucks ass. Admittedly, that's my bias.