That’s Why It’s So Cold on a Plane

I normally enjoy air travel. There are only a few things about it that
I don’t care for. And if you manage to forget about having to
spend hours stuffed into a cramped seat with some kid kicking your seat back, my only remaining
issue is how low the temperatures in the passenger cabin usually are! So, is there an aeronautical reason for this
suffering? At first, I thought that by setting such freezing
temperatures inside the plane, airline companies were just trying to help passengers acclimate
to different weather conditions. After all, the weather might be way colder
in the place they’re heading to. Well, I was wrong. Despite how ridiculous it may sound, chilly
winds are blowing through the passenger cabin to provide you with maximum comfort! Wait, what? First, the temperature in the cabin isn’t
as cold as it may seem. It’s normally kept between 71 and 75 degrees,
and rarely drops lower than 64 degrees. In fact, that’s the average temperature
in most office buildings; so what’s the problem? Don’t forget that while traveling by plane,
you don’t get up from your seat and move around very often. As a result, your body doesn’t produce enough
heat to warm itself, and you feel colder than you would under different circumstances. On the other hand, if the cabin is fully occupied,
the passengers themselves give off enough heat to significantly warm the cabin. Anyway, it turns out that there’s a connection
between the pressure and temperature in the passenger cabin, and people fainting mid-flight! First and foremost, passengers tend to lose
consciousness in the air more easily than on the ground, due to a special condition
called hypoxia. It occurs when the body tissues (including
the brain) don’t get enough oxygen and can’t work properly. But if the temperature on board the plane
is too warm, and the pressure is higher than normal, these factors can worsen and increase
the probability of a negative reaction. Of course, in different people, body temperatures
vary, and the temperature that’s comfortable for one person may seem too hot or too cold
for another. But just to be on the safe side, airline carriers
prefer to keep temperatures in the passenger cabin a bit lower than normal. And if you put it this way, I’d rather wear
several additional layers of clothing than allow that poor guy next to me to black out. However, you’re not as likely to be shivering
throughout the flight if the plane you’ve taken is new. The thing is that newer aircraft have more
advanced thermostats, which can regulate cabin temperature more precisely. And even though it’s impossible to adjust
the temperature around individual seats, flight attendants can regulate it by zones. By the way, cabin crew members will usually
only raise the temperature after passengers ask them to, because they don’t usually
have an issue themselves with the chilly temps. After all, flight attendants are constantly
working and moving while the passengers stay in a relaxed state, and that’s why their perception
of a comfortable temperature is very different from yours. And finally, have you noticed how hot it is
on the plane before it takes off, especially in contrast to the mid-flight chill? The thing is that the air conditioning on
the aircraft is always turned off to save fuel until the plane leaves the ground. As a result, the combined body heat of all
the people onboard, plus the absence of the air conditioning, can warm the cabin up to
an uncomfortable temperature. The maximum temperature on the plane shouldn’t
be more than 90 degrees, but luckily, you’re unlikely to experience such heat while flying. Ok, now it’s clear that the passenger cabin
is so cool for your own comfort. But what about its dryness? Is this gripe unreasonable as well? Nope, even pilots admit that the average passenger
cabin is incredibly dry and, thus, dehydrating. It has just 12% humidity, which is way drier
than most deserts! Unfortunately, airplane manufacturers can’t
do much to solve this problem. The dry air is a byproduct of flying at extremely
high altitudes, where there’s almost no moisture whatsoever. Of course, humidifying equipment in the cabin
could partially deal with this problem. But that equipment is pretty expensive, and
the results wouldn’t be worth the money. What’s more, the increase in moisture levels
on board could cause the guts of the airplane to corrode. By the way, what’s the most comfortable temperature
for you on board the plane, and how do you deal with the chill in the passenger cabin? Let me know down in the comments! Anyway, now the temperature inside the plane
makes sense to me. But what about the cargo hold of the airplane
where your dear pets travel? What are the conditions in there? Many people are surprised to know that the
hold is pressurized, just like the passenger cabin. On top of that, to air-condition the cargo
hold, they use the same air as in the cabin. However, since this air is directed from somewhere
else, it ends up a bit cooler when it reaches the cargo hold, which is also less insulated
than the passenger cabin. That’s why cargo hold temperatures, although
varying depending on the plane type, normally don’t get higher than 45 degrees. Isn’t that too cold for the animals that are
transported in the cargo hold? No need to worry: the bulk area where they’re
kept is heated up to 64 degrees. And finally, if a plane is transporting goods
that are sensitive to temperature, there are special cargo bins with temperature controls
inside. But if the temperature inside the cargo hold
isn’t that freezing, and the air is pressurized, why do stowaways rarely survive this experience? The problem is that these people don’t hide
in the cabin or hold, but in the wheel arches. And those are fully exposed to the elements. And as you know, the higher a plane climbs,
the colder it gets. If the temperature before take-off is about
70 degrees F, then at the altitude of 35,000-40,000 ft, which is the usual cruising altitude,
it can drop to -70 degrees F! Very few people are prepared enough to hold
out in such low temperatures, even for an hour. By the way, do you know why airplanes leave
white trails, also called contrails, in the sky? To tell you the truth, I’ve always thought
it was some sort of emission, just like those produced by old cars. But it turns out the contrail appears for
the same reason you can see your breath in cold weather! The exhaust from the plane is humid and hot,
and when it mixes with the frigid air and low pressure at cruising altitude, the water
vapor not only condenses, but can also freeze. This process looks exactly like streams of
white smoke in the sky, just like your breath on a cold day. Contrails can vary in their thickness and
duration, depending on the humidity and temperature of the atmosphere, as well as the plane’s
altitude. And that’s convenient, because you can look
at a plane’s contrail and predict the weather! Keep in mind that if a white trail left after
a plane is thin and short-lived, it means that up there, the humidity is low. Therefore, the weather is most likely going
to be clear. But once you see a thick and long-lasting
contrail, prepare for a storm – such a trail indicates high air humidity. From time to time, you might notice previously
straight and strong contrails become wavy, or even leave bizarre rings floating in the
sky. It means that up there, a plane is either
experiencing turbulence, or flying through air with different density and temperature. Another surprising phenomenon you’ve probably
witnessed is two planes flying nearby, but with one of them leaving behind a thick, long
trail, and the other – an almost invisible one. The reason may lie in the fact that different
planes have different engines. For example, if a plane has a newer engine,
its exhaust might have a lower temperature, so the contrail will differ dramatically from
the one left by a plane with an old engine. Besides, the length and thickness of the trail
depends on a plane’s power settings and cruising altitude. In this latter case, you might think that
the two planes are flying side by side, but in fact, that’s just a visual effect, and
they’re in different layers of the atmosphere. And since one layer can be way more humid
than the other, the planes leave different trails. So I’m done now, and it’s time to hit
the trail. Hey, if you learned something new today, then
give the video a like and share it with a friend! And here are some other videos I think you’ll
enjoy. Just click to the left or right, and remember:
stay on the Bright Side of life!

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