How cold is it really?

It’s that time of the year here in Pittsburgh, when I start cursing the first human who moved north of the tropic of Cancer from the bottom of my heart. For, once again, it takes me 10 minutes from when I’m “ready to leave” to when I actually leave the house after putting on many layers of socks, boots, half a dozen sweaters and coats, a couple of scarves, a hat and, of course, two pairs of gloves. (Whew! It was exhausting just typing all that!)

pit winter

It’s not the actual below-freezing temperatures which get to me, mind you. It’s the wind – the terrible wind which whistles through the little holes in your hat and freezes your ears, finds the little spot of skin that you forgot to cover up and turns it into ice as you wait for the bus in the morning.

You might’ve noticed this too: some days the temperature might read 0 degrees and it feels like you’re living in the Tundra and on other days – especially those days when it’s sunny outside and there is not a whiff of wind in sight – 0 degrees is quite manageable! Which is why, when I check the weather in the morning, I pay little attention to the temperature listed; my eye automatically goes to the “feels like” temperature or “wind chill factor” given by the weather channels. Of course, what the weather “feels like” varies from person to person and is also affected by factors such as how long you stay outside, whether you’re standing in the sun or the shade, and what you’re wearing. The wind chill factor is just a way to quantify the terrible cold and to give you something to substantiate your claim when you say “OMG! It felt like -40 degrees outside!”.

Turns out the wind is more evil than we thought. Our body constantly generates heat, which gets transferred to the air molecules surrounding our body. When the wind blows, it steals these warm air molecules away from our immediate surroundings, causing us to generate more heat to warm up the air that replaces it – which makes us feel colder. It’s akin to when you blow on your steaming cup of coffee to get it to be slightly cooler so you can actually drink it. Every time you blow on it, the heat from the top of the beverage is transferred to the air you’re blowing, and the beverage loses a little bit more heat.

A way to quantify this effect was originally concocted in the 1930s, by two men (Paul Siple and Charles F. Passel) who were working in Antarctica. They filled plastic containers with water and hung them from a pole outside their window. Every day, they measured the temperature outside, the speed of the wind, and the rate at which the water in the container turned to ice, and came up with an equation to measure the effect of wind on the temperature. Weathermen started using this to report “feels like” temperatures in the 1970s. However, there were soon noticeable inconsistencies, such as how “feels like” -40 degree weather with wind seemed to be more manageable than “feels like” -40 degree weather without wind. It was soon discovered that these researchers had over-estimated the effect of the wind chill.

National weather agencies became worried that this over-estimation could lull people into a false sense of how cold it really is. For example, suppose the weather agency reports a miscalculated “feels like” temperature of -35 degrees instead of the correct “feels like” temperature of, say, -20 degrees. Everyone will prepare for a really cold day and bundle up, but to their surprise, it’s not as bad as they feared. These ordinary citizens now have a misconception about how to dress for -35 degrees – a misconception that could prove to be dangerous. If, at a later time, the thermometer really drops to -35 degrees but there is no wind, everyone will dress as though it’s -20 degree weather. Conceivably, this could be quite dangerous and maybe even fatal!

treadmill-coldIn order to stop misleading people, US, Canada and UK devised a new experiment in 2001 to re-evaluate how the wind chill factor is calculated. Twelve volunteers donned winter coats and walked on a treadmill inside a wind tunnel. Their internal temperature was measured using a rectal thermometer, and a small probe measured the skin temperature at their nose, forehead, cheeks and ears. They walked for 90 minutes at three different temperatures: 50oF (+10oC), 32oF (0oC), and 14oF(-10oC) when the wind was blowing at 4.5, 11 or 18 mph (7.2, 17.7, or 29 km/h)

Based on the measurements made, they came up with the following formula:

Tfeels like = 13.12 + 0.6215 * T0  – 11.37 * V +0.16 + 0.3965 * T0 * V+0.16,

where V is the wind speed and T0 is the temperature as seen on the thermometer. What this equation tells us is that the difference between actual temperature and “feels-like” temperature increases proportionally with increasing wind speed. Today, this is the formula used by the weather agencies to calculate the little number that appears on your phone.

Of course, knowing how the wind chill is calculated does not help me as I shiver my way to school in the morning, but at least now I know how prepared I need to be. Then again, does any amount of preparation help one survive Pittsburgh winters? I guess I should just be glad I don’t live in Oymyakon for now!

Seeing Isn’t Believing

Quick – which of these lines is longer?

If you're reading this, you're taking too long to answer the question.

If you’re reading this, you’re taking too long to answer the question.

If you said the one on the right, congratulations! You’re wrong, of course, but your brain is working perfectly well. This is an example of an optical illusion, an image specifically created to trick your brain. You probably saw a lot of these as a kid, and you may have even thought they were fun. I know I did. I remember finding optical illusions in books, learning about the trick, and then quizzing classmates about them (I was a strange kid). I got satisfaction from knowing the trick to the picture, especially when others couldn’t see the illusion.

Once I got through graduate school, though, I realized that there are a lot of times where knowing the trick just brings up more questions. For example, let’s look at those lines again:

If you're reading this, you're taking too long to answer the question.

Yup, still lines.

The right one still looks longer, right? But we absolutely know that these lines are the same length! That’s why, to me, the big question is this:

Why does the illusion still work, even after we know the trick?

Continue reading

Desensitizing an academic

When my research manuscript was rejected from my first choice journal, I felt my heartstrings tug. I swallowed my emotion, and methodically analyzed every comment from the reviewers. I considered the reviewers’ reasons why my experiment was insufficient and (begrudgingly) assessed why my conclusions were inadequate. I finally addressed each suggestion with new time-consuming experiments. After six full months of poring over this manuscript, bright eyed and hopeful, I submitted it to a second journal. When it was rejected again, I cried.

My adviser had a different reaction to the ordeal. The first time my manuscript was rejected, he read over the reviewers comments with a steely glare. He remained stoic, other than a slight frown. He finally exhaled a stern “Okay.” Over the course of those next six months, he calmly pored over all my edits. Our discussions on each reviewer’s comments were always sharp and concise. My adviser’s reaction the second time my manuscript was rejected: steely glare, slight frown, stern exhale, “Okay.”
Continue reading

Why computer scientists and linguists don’t always see eye-to-eye

Linguists have many theories about how language works. How much should computer scientists who work on language care?

Linguists have many theories about how language works. But how much should the computer scientists who work with language care? (CC image courtesy of Flickr/surrealmuse)

“You’ve just explained my entire life to me.” This was the last thing I was expecting to hear from Lori, my graduate advisor, in the midst of a discussion of my career plans. I gave a stiff smile and shifted uncomfortably in my chair. “What you just said,” she continued, “that’s why I’m here, not in a linguistics department. In a linguistics department in the 80’s, I might have felt like a hypocrite.”

What I’d said hadn’t been a deliberate attempt to enlighten a researcher 30 years my senior. I’d simply mentioned my preference for application-oriented research groups, because I care more about producing useful insights than true theories. Apparently, though, the distinction between usefulness and truth struck a chord with Lori: in the field she and I work in, what’s useful isn’t always true, and what’s true is often not useful. Lori, a linguist in a school of computer science, has found her career path to be largely determined by that distinction.

Continue reading

Brain Power on the Baseball Field

titlePictureI was sitting in my college dorm room, working on some engineering homework, but I just couldn’t focus. My mind kept wandering back to the game. How could I have played so poorly? My teammates must hate me. Did I cost us a chance at the playoffs?

In college I played on the varsity baseball team and studied mechanical engineering. I worked hard on the practice team for 2 years and finally got my shot to start at third base as a junior. But things weren’t going according to plan. Third base has a long throw across the infield to first base, and I was having trouble making the throw accurately. By itself, this wasn’t unusual; every player goes through his funks and eventually works out of it. But despite hours of extra practice, I was stuck in a rut. My frustration culminated in a game in which I committed 4 throwing errors and we lost to an important division opponent by 1 run. My teammates had battled tooth and nail to make it a close game, and I literally threw it all away.

Continue reading

Measuring the Worth of One’s Salt

The crowd milling around the salt boutique is a mix of young bohemians and bourgeois baby boomers, all looking to add some flavor to their lives. The description of every product is written in transcendent prose that describes how each salt formed in a distinct, yet ‘natural’ environment, free of human interference. This salt was then harvested, often times with wooden tools, and transported thousands of miles for your purchasing pleasure. These specialty salts come in a variety of colors and have distinctive names representing their proud origins. For these distinctive salts, you can expect to spend about fifty times more per ounce than you would pay for your average table salt at a supermarket.

Salt_Pic_#1

From left to right: Specialty salts Himalayan Pink Mineral Salt and Kala Namak Black Indian Salt, and generic table salt

Continue reading

On Mathematics, Mandelbrot, and Beauty

I have a confession to make. I suck at math. I always have, and maybe always will. Despite possessing two engineering degrees and being very close to completing a third, I can’t say that I am comfortable with math. So you might be surprised if you ever drop by my office on a Sunday afternoon. You’ll find me with a broad smile on my face, leafing through a big fat book titled something like ‘Advanced Engineering Mathematics’. I read it because I want to, and I read it because it is fun.

“But math is hard!”, you say. I agree, but great difficulty does not always breed contempt. On the contrary, years of struggling with math have actually pushed me to a level where I have started to see the beauty in it.

To the uninitiated, the very notion of finding beauty in numbers and rigid logic might seem absurd. Nothing could be farther from the truth. Case in point – the pictures below:

Continue reading