Why Do Canada Geese Fly at Night?

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Why do Canadian geese fly at night?

Stefan Pociask:

There are actually very good reasons that these geese fly at night, and I will go over them with you. But first ... I must point out that any goose you see that is carrying a valid passport from the great country of Canada, may be called a Canadian Goose. All others should be referred to by their actual name, which is Canada Goose, or Branta canadensis, if you prefer.

I can’t count how many nights at 10 p.m., at midnight, at 3 a.m., and any and all other hours of the night, I have had that all too familiar “Honk! honk-honk-honk HONKhonk HONK HONKhonkhonkhonk HONK honk HOOOONK!” cacophony pass right outside my bedroom window, as the familiar flying-V formations of Canada geese fly over my home.

Those V formations are quite extraordinary. You can’t tell from the ground, but the lead goose is the lowest of the bunch. Each goose behind is slightly higher than the one in front of it, all the way to the last goose, which is flying the highest. They do this because of the aerodynamics of their wings. The only goose that is using all its wing power is the lead goose—point-man, so to speak. When that goose flaps its wings, it causes a certain turbulence of the air that’s following the wing. The next goose in line benefits from this swirling air, and doesn’t need to apply 100 percent of its wingpower. The next goose again benefits from that one, and so on down the line. Flying in formation this way adds 71 percent more distance that they can fly, than when flying alone.

So who gets chosen to be point-man? You’d think the one with the map! Or ... the leader? Or the new guy? No. None of these. They actually take turns. When one gets tired, he will drop back so he can rest a bit and benefit from another goose’s turbulence. When migrating ... in good weather ... with favorable winds, a strong tail wind ... these guys can make up to 1500 miles in a single day ... Hard to imagine, but it’s been done. They are migration masters.

So … the flying at night thing … I’ve already touched upon one of the reasons they prefer the night. It has to do with that turbulence I just mentioned.

You see ... many other large birds (and these are large birds) use thermals to gain altitude and to soar on. Raptors do this. Hawks, eagles, etc. During the day, the landscape is riddled with all kinds of thermals rising from the ground, all depending on what the surface looks like below; how much heat was absorbed and stored from the sun; if it’s dark or light … or even water. These thermals are great for raptors—lots of vertical air movement, all over. But geese don’t soar, and they don’t have need to fly in circles. They have somewhere to go. And all those daytime thermals are a pain in the butt; doesn’t make for smooth sailing. Plus, they interfere with the aforementioned wing turbulence that they use to keep from tiring. At night, several hours after sunset, the Earth cools and those pesky vertical thermals disperse.

So that’s one reason they like the night. Another reason for night flight is to prevent overheating (makes sense, right?). Nights are cooler, so birds that expend a lot of energy with constant flapping (as opposed to soaring) take advantage of the cool of the night.

A third reason is also something I’ve already mentioned. Hawks! And eagles! And falcons! All those guys are diurnal hunters, meaning they hunt during the day. Which goose in its right mind would want to share the not-so-friendly skies with something called a raptor? Now, if you’ve ever seen flocks of geese on the ground and tried to get amongst them or feed them or something … you may already know how mean and nasty they can get. People have used geese instead of watchdogs. They are tough! Especially on the ground. But falcons, hawks, and eagles, hitting them from the air often spells doom. In other words ... their goose is cooked. During the day, they often rest and feed and rejuvenate in the water, where they are safe from raptor attack. As long as they stay in the water.

So given the choice, they take the red-eye.

Otherwise, this can happen ... (WARNING: Extremely dramatic footage follows of a falcon/goose battle. Also extremely exciting! Who will win?!)

You’ll certainly see Canada geese fly during the day. But the smart goose prefers the night.

All migratory birds are split up into three classes, regarding migration habits. Nocturnal Migrants, are the first classification, [and they fly] at night. This would include most of the seed-eating songbirds, such as sparrows and thrushes. They will fly all night, then rest up, top off the tank with food, and try to stay out of sight of raptors during the day.

The second group is the Diurnal Migrants, who migrate during the day. These are often the insect-eaters; jays, swifts, swallows, larks, etc. They benefit greatly from the daytime thermals during their journey—not for reasons of soaring, like raptors use thermals, but rather because these warm updrafts send up clouds of insects from the fields, right into the paths of the migrating birds, like a food delivery service. Most insects are so light that a gust of wind or a thermal current can lift them high into the air—and unwittingly into the beak of a hungry swallow.

And the third class of [migratory birds] are those that have a preference, but actually migrate day and/or night, depending on the circumstances. Canada geese, and many waterfowl, fit into this last category.

This post originally appeared on Quora. Click here to view.

What Would Happen If a Plane Flew Too High?

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Tom Farrier:

People have done this, and they have died doing it. For example, in October 2004, the crew of Pinnacle Airlines 3701 [PDF]  was taking their aircraft from one airport to another without passengers—a so-called "repositioning" flight.

They were supposed to fly at 33,000 feet, but instead requested and climbed to 41,000 feet, which was the maximum altitude at which the aircraft was supposed to be able to be flown. Both engines failed, the crew couldn't get them restarted, and the aircraft crashed and was destroyed.

The National Transportation Safety Board determined that the probable causes of this accident were: (1) the pilots’ unprofessional behavior, deviation from standard operating procedures, and poor airmanship, which resulted in an in-flight emergency from which they were unable to recover, in part because of the pilots’ inadequate training; (2) the pilots’ failure to prepare for an emergency landing in a timely manner, including communicating with air traffic controllers immediately after the emergency about the loss of both engines and the availability of landing sites; and (3) the pilots’ improper management of the double engine failure checklist, which allowed the engine cores to stop rotating and resulted in the core lock engine condition.

Contributing to this accident were: (1) the core lock engine condition, which prevented at least one engine from being restarted, and (2) the airplane flight manuals that did not communicate to pilots the importance of maintaining a minimum airspeed to keep the engine cores rotating.

Accidents also happen when the "density altitude"—a combination of the temperature and atmospheric pressure at a given location—is too high. At high altitude on a hot day, some types of aircraft simply can't climb. They might get off the ground after attempting a takeoff, but then they can't gain altitude and they crash because they run out of room in front of them or because they try to turn back to the airport and stall the aircraft in doing so. An example of this scenario is described in WPR12LA283.

There's a helicopter version of this problem as well. Helicopter crews calculate the "power available" at a given pressure altitude and temperature, and then compare that to the "power required" under those same conditions. The latter are different for hovering "in ground effect" (IGE, with the benefit of a level surface against which their rotor system can push) and "out of ground effect" (OGE, where the rotor system supports the full weight of the aircraft).

It's kind of unnerving to take off from, say, a helipad on top of a building and go from hovering in ground effect and moving forward to suddenly find yourself in an OGE situation, not having enough power to keep hovering as you slide out over the edge of the roof. This is why helicopter pilots always will establish a positive rate of climb from such environments as quickly as possible—when you get moving forward at around 15 to 20 knots, the movement of air through the rotor system provides some extra ("translational") lift.

It also feels ugly to drop below that translational lift airspeed too high above the surface and abruptly be in a power deficit situation—maybe you have IGE power, but you don't have OGE power. In such cases, you may not have enough power to cushion your landing as you don't so much fly as plummet. (Any Monty Python fans?)

Finally, for some insight into the pure aerodynamics at play when airplanes fly too high, I'd recommend reading the responses to "What happens to aircraft that depart controlled flight at the coffin corner?"

This post originally appeared on Quora. Click here to view.

Why Are Some Men's Beards a Different Color Than Their Hair?

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Throughout civilization, beards have acted as a silent communicator. For some, it's a symbol of virility and power. For others, being hirsute is mandated by religion, marital status, or both. (Amish single men are clean-shaven; husbands are not.) Seeing an unkempt, scraggly beard could be an indication of a person's economic status or their lack of vanity. One man, Hans Langseth, sprouted a 17-foot-long chin warmer for the unique identity it afforded him. (He kept it neatly rolled over a corn cob when he wasn't busy showing it off.)

Langseth's whiskers, which wound up in the Smithsonian, present a curious timeline of his life. The furthest end of the beard was a vibrant brown, grown out when he was younger. The ends closer to his face—and to the end of his life in 1927—were yellowed.

While age can certainly influence hair and beard color, it doesn't explain why a younger man can sport a decidedly different beard tone than what's on the rest of his head. Other follicular forces are at work.

By default, scalp hair is white. It gets its color from melanin, turning it everything from jet black to dirty blonde. Pheomelanin infuses hair with red and yellow pigmentation; eumelanin influences brown and black. Like shades of paint, the two can mix within the same hair shaft. (Melanin production decreases as we age, which is why hairs start to appear gray.) But not all follicles get the same dose in the same combination. While you might sport a light brown top, your beard could be predominantly dark brown, or sport patches of lighter hairs in spots. Eyebrow hair will probably appear darker because those follicles tend to produce more eumelanin.

If you're wondering why these two-toned heads often have a red beard but not red hair, there's an answer for that, too. While all hair color is genetic, one gene in particular, MC1R, is responsible for a red hue. If you inherit a mutated version of the gene from both parents, you're likely to have red hair from head to toe. (Hopefully not too much toe hair.) But if you inherit MC1R from just one parent, it might only affect a portion of your follicles. If that swatch of color annoys you for whatever reason? There’s always beard dye.

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

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