You know, making all these videos is pretty
exhausting work. What I need is a vacation. Somewhere far away, preferably exotic, and
must be exciting! Korea? Or maybe Japan? Great food, fantastic culture, plenty of ways
to embarrass myself by misunderstanding the local customs. What’s not to love? But I noticed something strange while booking
my Asian getaway. My plane seems to be making a detour over
Alaska… Why is my airline going out of its way to
avoid the Pacific Ocean? Is this a mistake? Did I accidentally sign up for the caribou
route? At first you might think it was a safety issue. The Pacific is the largest and deepest of
the world’s oceans. If a plane encounters a problem over a seemingly
endless and bottomless pond of water, the pilots are going to have a rough time finding
a safe spot to set her down. Alaska might not be overpopulated with international
airports, but it’s a lot better than the middle of the ocean. How’s that for a tourism slogan? “Alaska, at least it’s better than sinking!” Okay, I apologize Alaska… Guessing that it was a safety precaution wouldn't
be entirely wrong. When planning a route, many pilots prefer
to maximize the number of airports along their path. Emergencies are incredibly rare relative to
how many planes take to the skies every day. But I can't think of many things more stressful
than losing an engine 30,000 feet over the middle of the Pacific Ocean. That said, it isn’t the main reason airlines
tend to avoid making a straight shot east to west. Ultimately, it comes down to saving fuel and
time. It’s easy to forget that an airline is a
business. A business whose profits depends on how quickly
and cheaply it can move passengers between destinations. People also prefer to get to their next stop
as quickly as possible, so it's a win-win for both airlines and passengers. Long story short, which is not my forte, speed
is usually the primary factor in determining a plane's flight path. Excluding special circumstances such as passing
through the jet streams or other meteorological concerns, the fastest croute is almost always
the one closest to a straight line. But wait, just look at that flight path – it’s
anything BUT a straight line! Well, yeah, when you look at it on a flat
map. But our planet isn’t flat now, is it? It can be confusing since we’re used to
looking at our world on a two-dimensional plane. Unless you bust out a globe each time you
need to check where some city or country is located, you probably look at a world map. So, on a 2D map, making a giant rainbow to
avoid the Pacific Ocean looks like a much longer route. But since the Earth is a sphere (eh, more
or less, but more on that later), a straight line is going to look very different in three-dimensional
spaces. Ok, let’s do a little experiment. Got a globe nearby? Oh yeah, I just said most of us use Google
maps... Alright, here, I’ll show you on mine. I’ll put one end of a string on Los Angeles
and the other end on Tokyo. When I pull it taught, you'll notice that
the string isn't running exactly parallel to the lines of latitude printed on the globe. Instead, it’ll bend slightly upwards as
it follows the curvature of this mini Earth I got at the bookstore down the road. This effect is even more pronounced in practice
because my globe isn't a perfect recreation of the real deal. In fact, the problem is that it’s too perfect! You see, unlike a globe, the Earth isn’t
a perfect sphere. Our planet is slightly bigger around the middle,
kinda like me after the holidays! Wait who wrote that? Humph! When looking at pictures taken from outer
space, the difference isn't enough to notice. The planet is so big that it’s easy to lose
track of a few hundred miles here and there. But check it out: if you could take a giant
string and measure the Earth’s circumference through the poles, you’d need 24,860 miles
of string. But if you do the same thing at the equator,
it’d jump up to 24,900 miles. Why is that, you ask? It’s because our planet rotates on its axis. Ever spin yourself really fast on the playground
merry-go-round when you were a kid? Remember feeling like the thing was going
to throw you out to the sides? No I remember I was throwing up a lot. Not a good ride for me. Anyway, Something similar happens to the Earth’s
midsection as it spins – the force causes it to bulge out. Yes, it’s spinning fast enough to do that! Anybody tuning in from the equator right now,
you’re currently moving about 1,000 mph! That 40-mile difference in the Earth’s width
might not seem like very much. But when it comes to the surface area of an
entire planet, that little bit of added girth can go a long way. The combination of these two factors, the
curvature of the Earth and its extra equatorial width, ooh I like that, mean that curving
toward the poles is a shorter distance than flying (what seems like on a map) “straight”
across! None of this is to say that planes never cross
the Pacific Ocean. People have to get to Australia somehow! I guess… I’m not so much into giant insects and spiders
but, hey, to each his own! Just kidding Australia! Anyway, planes will also venture over open
water to avoid storms. While aircraft can outclimb some types of
severe weather such as hurricanes and tropical storms, seemingly mundane thunderstorms are
surprisingly challenging! With clouds reaching altitudes of over 60,000
feet, airplanes are advised to steer around instead of into or over them. It’s almost unheard of for modern aircraft
to be brought down by severe weather, but bad enough turbulence can cause injuries to
passengers and crew as they (and all the stuff they’ve packed with them!) get tossed around
the cabin. The takeaway here is keep your seatbelts fastened
at all times. Another reason planes will sometimes brave
an oceanic voyage is to take advantage of the smoother ride. Even in clear weather, there’s much less
turbulence over water than over land. This is because the primary source of turbulence
is hot air rising up from the ground. Hey there’s a lot of hot air rising up from
this microphone! Water distributes heat a lot better than soil,
so flights over the ocean are often much smoother. The other primary consideration for determining
flight paths are air currents, namely the jet streams. These high-altitude air currents exist near
the top of the troposphere. That’s the lowest layer of the Earth's atmosphere
and the one where most weather occurs. The border between the troposphere and the
next layer up, the stratosphere, is known as the tropopause. Its altitude fluctuates between 4 and 12 miles
above the Earth’s surface. This fluctuation results in rapid shifts in
air temperature and pressure, which creates a wind tunnel that can reach speeds of over
200 mph! These extreme speeds are most common in winter
when the temperature difference is greatest, but regular wind speeds of 80 – 140 mph
are nothing to scoff at! So keep your scoffing to yourself! There are 4 main jet streams, 2 in each hemisphere,
and thanks to the Earth’s rotation, they mostly flow west to east. The two most important for air travel are
the polar jet stream, which forms near the arctic circle, and the subtropical jet stream
near the equator. Both are thousands of miles long despite being
only a few miles wide. Flying with a jet stream can shave several
hours off of a trip, but flying into it can slow the plane down considerably. It’s also worth noting the risks associated
with jet streams. The biggest hazard is a kind of turbulence
known as clear-air turbulence, which occurs along the edges of the streams. This kind of turbulence is nearly impossible
to predict and far more intense than the usual variety. Turbulence-related accidents are rare, but
they are possible. One particularly serious incident happened
in 1997, when a plane flying from Tokyo to Honolulu suddenly dropped after hitting a
patch of clear-air turbulence. The pilots were able to regain control, but
many passengers had been thrown from their seats really hard by the sudden descent. With that danger in mind, flight plans need
to be carefully calculated to take advantage of the jet streams without putting the plane
at risk. Repeat after me, keep your seat belts on at
all times while flying. Understanding why planes take the routes they
do often comes down to facts we don't usually think about in everyday life. The jet stream mostly affects things tens
of thousands of feet in the air, and the curvature of the Earth doesn’t really matter unless
you’re traveling hundreds of miles per hour over vast distances. I don’t know about you, but my car can’t
quite manage either of those things. At least not yet. I have a few ideas, but we'll save that for
a video titled "7 Things You Shouldn't Strap Rockets To." Ha ha. Hey, if you learned something new today, then
give the video a like and share it with a friend! And here are some other cool videos I think
you'll enjoy. Just click to the left or right, and stay
on the Bright Side of life!
