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When 85 degrees isn’t 85 degrees

* Today’s weather post is brought to you by the dying hiss of a fan as the power goes out for the third time in the past hour, your high school geometry class, and that friend in the U.S. who says, “Oh, yeah, it’s 85 degrees here, too. It’s soooo hot.” *

I love it when I’m visiting the States and people ask me, “So, is it, like, really hot over there where you live?”

I LIVE ON THE EDGE OF THE SAHARA DESERT. I’m pretty sure hell has cooler days than we do.

But I’ve come to understand that “hot” can look very different, depending on where you’re standing on the planet, and depending on lots of magical atmospheric alchemy stuff that pretty much only a scientist can explain.

Let me just qualify this by saying that I’ve experienced plenty of places with hot weather. I’ve been to deep south Georgia in the summer, to Texas and Arizona and El Salvador. I grew up sleeping in an attic bedroom with no air conditioning. But none of those places even comes close to the suffocating-under-a-wet-blanket feel of “hot” in sub-Saharan Africa.

So what gives? Why does 85 degrees here make me want to punch someone in the face, while 85 degrees in Michigan is perfect for a day out at the park? I’m no weather expert, but I can share with you a few important things I’ve learned on this subject.

First: geometry. (Shout out to my 9th grade geometry teacher, Mrs. Ferrin: you were right — geometry IS useful in real life!)

The earth is curved, which means that the angled places don’t receive as much direct energy from the sun. So while the areas near the equator (i.e., Dakar) are bearing the full brunt of the sun’s wrath, the areas further away (i.e., Detroit) are getting the more pleasant diluted rays that create temperate weather like fall and spring. It’s also why there is very little variation in the time the sun sets here — it’s dark by 7:30 year-round — and only two seasons: hot and rainy, and slightly less hot and dry.

Or, you can think of it like this: Imagine Dakar and Detroit are standing next to each other, and Cyclops from the X-Men takes off his sunglasses and looks directly at Dakar. Dakar gets vaporized. Detroit — you just get a sunburn.

Here’s a handy science illustration to help explain.

sungeometry
There are, of course, other factors that contribute to what real meteorologists call the “heat index.” I call it the anger index because it’s directly related to the probability that I will explode at the slightest provocation; for example, Rick asking me what’s for dinner.
You might be thinking —“yeah, what about humidity?” (We’re lucky enough to live in an area where the desert meets the ocean, so we hit the weather jackpot of desert heat/dust AND humidity that makes it feel like you’re breathing with a plastic bag over your head.) But humidity doesn’t tell you the whole story. Apparently what you need to forecast the heat index of a given day is something called Dew Point.
I have tried to understand dew point — I really have. It sounds simple: “the temperature at which a given concentration of water vapor in air will form dew.” I still have no idea what that means in terms of how hot it feels. All I know is that if the dew point is over 70 degrees, you’re basically sitting in a pool of sweat because your perspiration doesn’t evaporate. Meteorologists say a dew point over 70 makes “hot” feel “oppressive.”
Today the dew point in Dakar is 78.
I’ll let you do the rest of the math:
  • Multiply number of power outages by the ridiculously expensive rate you are charged for said power
  • Compound by the fact that central air doesn’t exist in Dakar
  • Add frustration of non-functioning AC split unit, even though you can’t afford to run it during the day anyway
  • Add a layer of dust to the exponential power of ten

(or, you can just use this handy heat index calculator from the weather prediction center)

And you end up with today’s heat index of: 102.

That’s right. There’s a 102 percent chance that someone in my family is going to ask for a grilled cheese sandwich and get served up a heaping plate of OH NO, YOU DID NOT JUST ASK ME TO TURN ON THE STOVE.

So there you have it — an explanation of why 85 degrees isn’t always 85 degrees.

* Full disclosure: I sleep with the AC on in my bedroom at night during hot season, which goes a long way in keeping me sane — as long as the power doesn’t go out. There’s nothing more groan-inducing than the sudden silence of a power outage at 3 a.m. I also make up errands during the day and drive as slow as possible so I can bask in the direct vent of freon in our pickup truck.

1 comments On When 85 degrees isn’t 85 degrees

  • After reading all of your blogs, I’m wondering if you are punching them in the face with your “fat fist”? These are amazing !!! I’m sorry it’s so hot..

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