Why Does 60-Degree Water Feel Colder Than 60-Degree Air?

istock.com/nikamata
istock.com/nikamata

A question from reader Josh: "Why does 60-degree weather feel warm to us, but if we get in the ocean or pool and it's also 60 degrees, we feel freezing?"

If the air and the water are the same temperature, what accounts for the difference that we perceive? It's a matter of heat transfer, the transition of thermal energy from a hotter object to a cooler object.

As long as the temperature of your body is higher than the temperature of the surrounding medium (air or water, for example), your body will give off heat. As soon as the surrounding temperature becomes higher than that of your body, though, you'll start to absorb heat.

The amount of heat that moves between your body and the surrounding medium and the speed at which it moves, both of which are important to the sensation or warmth or cold that we feel, depends on how good a conductor the medium is. The reason the water feels colder than air is because water is the better conductor of the two. When you hop into that 60-degree pool, heat escapes your body much more easily than it would if you were standing beside the pool in 60-degree air. Because the water takes more heat from your body, and quicker, it feels colder.

More on Temperature

The Fahrenheit temperature scale was proposed in 1724 by physicist Daniel Gabriel Fahrenheit (1686-1736). The scale is based on three reference points of temperature set by Fahrenheit: the 0-degree point was set by placing the thermometer in a brine of ice, water, and ammonium chloride; the 32-degree point was set by placing the thermometer in water that had ice forming on the surface; the 96-degree point was set as the temperature given when Fahrenheit placed the thermometer in his mouth or armpit. Later, other scientists redefined the scale slightly (hence, normal body temperature is 98.6 and not 96). Fahrenheit's scale has been replaced in most countries by the Celsius scale, but is still used for non-scientific purposes here in the US and a few other countries (hey there, Belize!).
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40 degrees below zero is the same temperature on both the Fahrenheit and Celsius scales.
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The "451" in Fahrenheit 451 refers to the temperature at which the paper of a book spontaneously ignites when exposed to heat. Modern scientific sources give the actual average temperature as 572°F (and author Ray Bradbury's contemporary sources would have given him 842°F), though Bradbury's title temperature still has a nicer ring to it.

Why Are There No Snakes in Ireland?

iStock
iStock

Legend tells of St. Patrick using the power of his faith to drive all of Ireland’s snakes into the sea. It’s an impressive image, but there’s no way it could have happened.

There never were any snakes in Ireland, partly for the same reason that there are no snakes in Hawaii, Iceland, New Zealand, Greenland, or Antarctica: the Emerald Isle is, well, an island.

Eightofnine via Wikimedia Commons // Public Domain

Once upon a time, Ireland was connected to a larger landmass. But that time was an ice age that kept the land far too chilly for cold-blooded reptiles. As the ice age ended around 10,000 years ago, glaciers melted, pouring even more cold water into the now-impassable expanse between Ireland and its neighbors.

Other animals, like wild boars, lynx, and brown bears, managed to make it across—as did a single reptile: the common lizard. Snakes, however, missed their chance.

The country’s serpent-free reputation has, somewhat perversely, turned snake ownership into a status symbol. There have been numerous reports of large pet snakes escaping or being released. As of yet, no species has managed to take hold in the wild—a small miracle in itself.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

If March 15 Is the Ides of March, What Does That Make March 16?

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iStock.com/bycostello

Everyone knows that the soothsayer in William Shakespeare's Julius Caesar was talking about March 15 when he warned the Roman emperor to "beware the Ides of March." We also all know Caesar's response: "Nah, I gotta head into the office that day." But if March 15 is the Ides of March, what does that make March 16?

At the time of Caesar's assassination, Romans were using the Julian calendar (introduced by Julius Caesar himself). This was a modified version of the original Roman calendar, and it is very similar to the one we use today (which is called the Gregorian calendar). A major difference, however, was how Romans talked about the days.

Each month had three important dates: the Kalends (first day of the month), the Ides (the middle of the month), and the Nones (ninth day before the Ides, which corresponded with the first phase of the Moon). Instead of counting up (i.e., March 10, March 11, March 12), Romans kept track by counting backwards and inclusively from the Kalends, Ides, or Nones. March 10 was the sixth day before the Ides of March, March 11 was the fifth day before the Ides of March, and so on.

Because it came after the Ides, March 16 would’ve been referred to in the context of April: "The 17th day before the Kalends of April." The abbreviated form of this was a.d. XVII Kal. Apr., with "a.d." standing for ante diem, meaning roughly "the day before."

So, had Julius Caesar been murdered on March 16, the soothsayer's ominous warning would have been, "Beware the 17th day before the Kalends of April." Doesn't have quite the same ring to it.

This story first ran in 2016.

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