Katabatic Winds

If you have ever spent an evening on the slope of a mountain, you know the temperature will precipitously drop as soon as the sun sets. Part of this is the dry mountain air that does not hold on the heat well. However, most people also notice that the wind picks up dramatically, and you had better throw on another layer or two before it gets too cold.

By Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany - Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=2270406
The two forces (pressure gradient and gravitational force) producing Katabatic winds at the edge of an ice sheet or glacier.

These reason for this change in wind is the presence of katabatic winds. These winds, which roughly translate to, descending winds, in Greek, rush down the side of the mountain every evening. The katabatic winds are created by the sun heating up air during the day, causing it to rise up the side of a mountain or other slope. As the sun heats the air, it rises up like a slingshot being pulled back. As the sun sets behind the mountain, the dry mountain air rapidly cools and becomes denser. The dense air flows back down the mountainside, gaining momentum and it rolls down the slope — often creating a significant drop in wind chill.

Most katabatic winds are mild in nature, usually just 10 to 15 miles per hour, but some winds, such as those in Antarctica can reach hurricane speeds of up to 200 miles per hour. I have personally experienced 60 to 70 mile per hour katabatic winds in the Kali Gandaki river valley in Nepal, which sits in between two 26,000 foot mountains in a very dry high mountain plain.

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Incomplete Presidential Terms


A couple of years ago, I did a post on the eight Presidents who died in office and the Curse of Tippecanoe. This got me thinking about which Presidents did not complete their terms. There were, of course, the eight who died, plus one more, Richard Nixon, who resigned from office in 1974 facing impeachment and removal related to his role in the Watergate scandal.

The list of uncompleted Presidencies is below. The shocking thing is how often Presidents don’t complete their terms. We did well between Washington and William Henry Harrison, who was the ninth President in the 14th term. After that, it falls apart.

Incomplete Presidencies

PresidentElectedTermCause of DeathPresident NumberDeath Term Number
William Henry Harrison18401841Pneumonia914
Zachary Taylor18481849-1850Stomach Illness1216
Abraham Lincoln18601861-1865Assassinated1620
James A. Garfield18801881Assassinated2024
William McKinley19001897-1901Assassinated2529
Warren G. Harding19201921-1923Heart Attack2934
Franklin D. Roosevelt19401933-1945Stroke3240
John F. Kennedy19601961-1963Assassinated3544
Richard Nixon19691969-1974Resigned3747

Then, we went just two terms until Zachary Taylor died in the 16th term, and then only four more terms until Abraham Lincoln was assassinated in the 20th terms.This pattern of three to six terms until the next incomplete Presidency continued until Nixon, who resigned in the 47th term.

It is interesting to note that we are long overdue for a President to fail to complete his term, as Donald Trump is the 45th President, serving the 58th term — a gap of 11 terms since Nixon resigned.

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Lonely, I’m Mr. Lonely

Lonely, I’m Mr. Lonely, I have nobody for my own. I am so lonely, I’m Mr. Lonely, wish I had someone to call on the phone.

Where is the farthest you could possibly be from other people? The answer is the Oceanic Pole of Inaccessibility, more colloquially known as Point Nemo (Latin for no one).

This remote spot in the southern Pacific ocean is almost 1,700 miles from the nearest other inhabited locations, the Easter Islands, and the Pitcairn Islands, both of which are incredibly remote themselves. In other words, it’s as if you went from San Francisco to St. Louis and did not see another person in between.

The craziest thing about Point Nemo is that the closest humans to you would be orbiting the Earth, on the International Space Station, a mere 258 miles away.

As an added bonus, the most remote place on land is Bouvet Island, an uninhabited island in the south Pacific that is, oddly, claimed by Norway as a dependency.

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See a Double Sunset

sunsetA couple of years ago, I asked the question, can you see across Lake Michigan. The answer is no, but a related question is whether you can see the sunset more than once in 24 hours. The answer to that question is, yes. For example, astronauts in the International Space Station are traveling so fast at such a height, that they see sixteen sunrises and sunsets in a 24-hour period.


The world’s tallest structures: 2560 BCE to Present. Note that for about 4,500 years the Great Pyramid at Giza was the tallest structure in the world — until the Eiffel Tower was completed in 1889.

It is possible, however, to see multiple sunsets right here on Earth. The world’s tallest building is the Burj Khalifa — Dubai’s 160-floor, 2,722 foot glass, steel, aluminum, and concrete behemoth. The Burj Khalifa is so tall that the timing of the sunset is affected and requires a special schedule during Ramadan. Residents above the 80th floor must wait two extra minutes before breaking their fast at sundown. Residents above the 150th floor must wait three minutes. In fact, it could be possible to watch the sunset at ground level and then take a fast elevator to the top and watch the sunset a second time. Fear not, however, you don’t even need to travel to the Middle East to go on your double-sunset date. You could, instead, travel to the beach and watch the sunset while lying down (water is better, because terrain is not flat enough). Immediately after the sun passes below the horizon, jump up, and a portion of the sun will still be visible, making it possible to see the sunset twice.

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A Time to Pee

Q: Why can’t you hear a Pterodactyl going to the bathroom?
A: Because the P is silent

This one is just too good to pass up. Patricia Yang is a doctoral student at Georgia Tech who studies “how animals urinate, defecate, and digest.” According to a 2014 paper called, “Duration of Urination Does Not Change with Body Size,” Yang and her colleagues used high-speed cameras on animals at the Atlanta Zoo to measure the time it takes them to urinate. They found remarkable consistency in the time it takes mammals greater than about two pounds to empty their bladders. Virtually all mammals take about 20 seconds to pee.

In and of itself, this does not seem remarkable, but leave it to National Geographic to put it into context for us. Look at this chart (copied here) on their Voices blog! A Great Dane puts out about 0.4 gallons of urine in the same time that an African Elephant gushes out 42 gallons.


And on that note, I’ve gotta go!


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The Days Get Shorter in the Summer


As the Earth orbits the Sun, we experience seasonal changes.

I asked people if they know why the days get shorter in the summer, and they all replied, you mean the opposite. Actually, no, I meant what I said, the days get shorter in the summer and they get longer in the winter.

The first day of summer for those in the northern hemisphere is the summer solstice, which happens every year between June 20 and 22. On this day, the Earth’s 23.5 degree tilt is most tilted towards the Sun. Consequently we get the most sunlight, and we call that the longest day of the year. Therefore, if the first day of summer is the longest day of the year, then each subsequent day during the summer is getting shorter — the days get shorter in the summer.

This pattern progresses until the winter solstice, which happens, in the northern hemisphere between December 21-22, which is the shortest day of the year and the first day of winter. After winter begins, the days get longer until summer, and the pattern repeats.

I personally think we should just move to two seasons: summer and winter. Summer should begin on the vernal equinox, what we refer to as the first day of spring. For the first half of summer the days would get longer, and for the second half, the days would get shorter.

This would continue until we hit the first day of winter, which is currently the autumnal equinox, or the first day of fall. On the first day of (new) winter, the days would continue to get shorter, until current winter solstice, after which the days would get longer.

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Size Does Matter

Planet Mass

Together, Jupiter and Saturn make up 92 percent of the mass of all eight planets combined. On the other hand, Mercury is so light that hardly appears in this chart.

You probably know that the largest planet in our solar system is Jupiter and that the second-largest is Saturn. You also know that Jupiter is massive: 1.898 \times 10^{27} kg, more than 317 times the mass of the Earth. In fact, if you total the mass of all the planets, Jupiter would make up 71 percent of that mass.

The more interesting planet size, to me, is Saturn, the second largest planet in our solar system. Saturn is a gas giant and has a density of 0.687 \frac{g}{cm^3}. Water, by definition has a density of 1 \frac{g}{cm^3}, meaning that Saturn would float on water. Of course, being lighter than water does not mean that Saturn is not heavy. Rather, Saturn is so huge (764 Earths would fit inside it) that it weighs 5.683 \times 10^{26} kg, or 83 times the mass of Earth, and is 21 percent of the mass of all the planets, which is more that the mass of all the non-Jovian planets combined.

Bonus Fact 1: Saturn is so massive that one of its moons, Titan, is larger than the planet Mercury.

Bonus Fact 2: The third-largest planet is Uranus, which is the butt of so many jokes.

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Presidential Deaths

Abraham LincolnYesterday marked an interesting milestone. It had been 18,967 days since a US President died in office. The last President to die in office, John F. Kennedy, was assassinated  on November 22, 1963. Prior to the current record, the longest period of non-death was April 30, 1789, when George Washington was inaugurated, to April 4, 1841, when William Henry Harrison died of pneumonia after only 30 days, 12 hours, and 30 minutes as President.

As of today, eight Presidents have died in office:

Presidents Who Died in Office

PresidentElectedTermCause of Death
William Henry Harrison18401841Pneumonia
Zachary Taylor18481849-1850Stomach Illness
Abraham Lincoln18601861-1865Assassinated
James A. Garfield18801881Assassinated
William McKinley19001897-1901Assassinated
Warren G. Harding19201921-1923Heart Attack
Franklin D. Roosevelt19401933-1945Stroke
John F. Kennedy19601961-1963Assassinated

Interestingly, with the exception of Zachary Taylor, all of the Presidents who died in office were elected in twenty-year increments, which has led the speculation of the Curse of Tippecanoe, which posits that Presidents elected in years ending in zero are cursed. Combined with assassination attempts on Ronald Reagan (elected in 1980) and George W. Bush (elected in 2000), the conspiracy theories abound.

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Airport Runway Names

Chicago’s O’Hare International Airport has sixteen different runways (keep reading, that actually means eight, of which five are used). The two most used runways are  27L (landings) and 28R (take-offs). Runways are named based on their direction on a scale of 1-36, which, when adding a zero to the end, designate the compass direction of the runway as you look down from the beginning to the end.

The compass is a 360 degree marking of a circle, with 90 degrees facing East, 180 degrees facing South, 270 degrees facing west, and 360 degrees facing North. For example, a runway marked 27, faces the compass direction 270, which is West. A runway marked 5, faces 50 degrees or Northeast (the runway might be facing 45 degrees, but is rounded to 5, so as not to use 4.5).

The direction you are facing matters. If you are looking down the runway from the South end of runway 36, you are facing due North. However, if you were at the other end of the same runway, but facing the other direction, the same runway would be marked 18, as it is also facing due south. In this way, not only are you able to tell which runway you are on, but which direction you should use it. So, runway 27 will be marked runway 9 on the other end, and runway 5 will be marked runway 23 on the other end.

Finally, most major airports will have parallel runways, so L-C-R designations are used for left, center, and right. At O’Hare, the majority of landings occur on runways 27L, 27C, and 27R. These three parallel runways face west and allow places from the East Coast to land without turning around — three-at-a-time.

As you may have surmised, facing the other direction, the runways have the opposite designations. 27L is 9R, 27R and 9L, and the center runway, 27C, is 9C.

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Why Does Soda (or Beer) Explode When Shaken?

Soda is pressurized with carbon dioxide gas, making it bubbly and fun-tasting. When you open a can or bottle, the pressure is released, and the gas expands to fill the greater volume, in this case, into the air around you. In most instances, the excess gas is on the top of the liquid and is able to freely expand into the air.

When the can or bottle is shaken, however, the gas is mixed with the liquid inside. Some of this gas gets stuck on the sides of the can or bottle. When that gas tries to leave the open can and fill the new volume, it takes the liquid with it, and you are left with the big mess.

The best way to prevent the mess is to tap the sides of the can prior to opening the can. Tapping the side dislocates the gas stuck on the sides of the can and lets it escape out the top, which is where you want it. Often, you see people tapping the top of the can. This is effective too; however, it is only effective in that tapping the top of the can causes vibrations down the sides of the can. It is more efficient to tap the sides directly.

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