Collecting Data: You’re Doing It Wrong

Sometimes, how you get your information is just as important as where you get it.

I’m not a meteorologist, nor do I play one on TV. My scientific background is in the realm of astronomy. While I’m not a professional astronomer, I am a professional historian and in the field of history, I’m a historian of science. When you study the history of science you obviously learn things about how science is done. You also learn how science is presented to the general population. Sometimes, in the case of Carl Sagan’s Cosmos, the presentation is amazing and changes lives. Other times, things get bungled but the general population doesn’t realize it.

This happened to me last night, and it started as soon as I left the library.

Last night a huge storm rolled through Queen Creek, Arizona. When I left I got caught in a microburst. Rain was falling in sheets and it was falling sideways because the wind was so strong. My fuel light came on during my trip to work so, rain or not, I needed gas. When I pulled off at the local convenience store and gas station, I was getting soaked standing under the awning because the rain was able to just blow through underneath it. However, it passed quickly and by the time I was done and safe in my car, I could actually see through my windshield again.

Still, apparently the storm moved in the direction I was going because as I drove the roads home, I drove right back into the storm that hovered over me when I first left work. It was pouring so hard that the road was flooded in several places and forced me to pull over once because the amount of rain hitting the windshield made it impossible to see. I had zero visibility and was forced to wait it out simply because there was so much rain.

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You're not a meteorologist just because you stand in front of a map on TV.

Then, when I got home, I found out that, when it comes down to it, none of that rain mattered because only a third of an inch fell at Sky Harbor International Airport. I turned to my wife and asked, “So, the only rain that matters is what falls at the airport? That storm I came through; they’re not going to count that as part of the rain fall because it didn’t fall on the airport?” It seems incredibly stupid and short sighted to gauge an area’s rainfall solely by what falls in such a small space. In astronomy, it’d be like looking at one tiny patch of sky and then deciding the entire universe looks just like that.

To get an idea of the enormity of this practice of gathering data in such a small space, let’s take a look at the sizes involved. Phoenix, Arizona is a big place, encompassing 519 square miles. If we care only about the rain in Phoenix, and not the rest of the Valley, then we’ll begin our calculations there.

According to their website, Phoenix Sky Harbor International Airport covers an area of 3,000 acres. That’s around 4.7 square miles. Which means the weather people on the telly are measuring rainfall for .9% of the total area of Phoenix. Keep in mind, there’s a decimal in that percentage and we’re only measuring precipitation for nine-tenths of one percent of the total area of Phoenix.

Look around you. Does your living space look like mine? It’s not messy, but it could use some tidying? Okay, now go tidy nine-tenths of one percent of it and invite your spouse to see if they even notice the difference. Gauging an area’s total rainfall from such a small place seems totally useless to me and, keep in mind, with that calculation we’re assuming that all of the airport is acting as a rain gauge.

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This was Phoenix... yesterday.

However, millions of people work in Phoenix and live elsewhere in the Valley and, likewise, millions were affected by the storm I went through and the sheets of rain falling from the sky. What about them? They too got soaked and flooded while only a third of an inch fell upon the runways. For that, the scale becomes even more absurd. The overall area of the Valley of the Sun is 16,573 square miles. If we are to only measure rainfall at the airport, then we are considering .03% (that’s three-hundredths of a percent) of the total area. I’m not sure how you clean three-hundredths of your house…. Maybe you wipe off a corner of a kitchen counter. Then again, that might be too much.

In comedy, we find truth and the best stand-up comics in the world are also some of our greatest philosophers. So I think George Carlin said it best when he said “Present temperature is sixty-eight degrees at the airport, which is stupid ‘cos I don’t know anyone who lives at the airport.”

Note regarding the picture of the sexy weather woman: Appearances can be deceiving. See the image below? Just another weather woman, right? No, actually she’s Jackie Guerrido and she really is a meteorologist.

2 comments

  1. you know, i have often wondered about this and my conclusion is: people just don’t care about rainfall amounts that much. the only solace i’ve ever found is in METAR weather information from airports. viz:

    http://weather.noaa.gov/weather/current/KDVT.html
    http://weather.noaa.gov/weather/current/KSDL.html
    http://weather.noaa.gov/weather/current/KLUF.html

    the ones nearest queen creek don’t seem to track precipitation:

    http://weather.noaa.gov/weather/current/KIWA.html
    http://weather.noaa.gov/weather/current/KCHD.html
    http://weather.noaa.gov/weather/current/KFFZ.html

    i should make a map to aggregate all this data automatically. One Day(tm).

    1. I’d love to see some kind of Google Map mashup using that information!

      And you’re right. People probably don’t care about rainfall amounts all that much, but I think the Phoenix area is a bit of an exception because we just don’t get any around here. And when we do, I think it’s completely unsatisfying for someone who watched hell rain from the skies at their house in Mesa to hear on the news that we only got a fraction of an inch. 🙂

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