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Because riding a motorcycle, I didn't feel a difference when riding in different directions.

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    $\begingroup$ Up to some wind velocity you probably won't hear a difference, but this certainly breaks down in turbulent wind flow. I don't off-hand know what speed that is for wind/air. $\endgroup$ – anon01 Oct 7 '16 at 2:54
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    $\begingroup$ Instead of riding a motorbike, try riding a bicycle. Occasionally you will experience this and it is especially noticeable on a windy day. It is a very peaceful and calming experience. $\endgroup$ – Qwerky Oct 7 '16 at 10:55
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    $\begingroup$ You'd notice the wind if you were riding your bike through a hurricane... which should tell you a lot about what effects are at play here. $\endgroup$ – HopelessN00b Oct 7 '16 at 16:33
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    $\begingroup$ you need to go at the same speed as the wind does. How fast was the wind going, and how fast was your bike going? $\endgroup$ – njzk2 Oct 7 '16 at 17:14
  • $\begingroup$ @Qwerky And it's even more noticeable when the wind is gusting, because you have alternating periods of calm and possibly intense wind resistance. $\endgroup$ – Michael Oct 7 '16 at 17:27
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Theoretically no you wouldn't hear or feel anything but obviously in reality not all of the wind is going the exact same direction and speed.

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    $\begingroup$ Any explanation as to why "theoretically" this is true? $\endgroup$ – Chris Cirefice Oct 7 '16 at 12:55
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    $\begingroup$ Sure, we are able to detect the sound and feeling of wind because air molecules bombard our senses. If our senses and the air molecules are in uniform motion with each other, they don't interact. $\endgroup$ – Yogi DMT Oct 7 '16 at 13:05
  • $\begingroup$ I think @ChrisCirefice 's point is that this isn't theoretical. It's easily demonstrated fact. Just stick a microphone on a trolley inside a wind tunnel $\endgroup$ – Carl Witthoft Oct 7 '16 at 15:36
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    $\begingroup$ I used the word theoretically because all components of the wind moving in uniform motion with a person isn't a realistic scenario. $\endgroup$ – Yogi DMT Oct 7 '16 at 15:51
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    $\begingroup$ I agree with Yogi's word choice. I think it's very valid to say "your mathematical thinking is valid, but in practice you're never going to be in an environment like that." Similar to how, in theory, spherical cows can stand up on friction-less surfaces... $\endgroup$ – Cort Ammon Oct 7 '16 at 21:57
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To really test the hypothesis, you should ride a balloon: it has no connection to the ground, there is no effect that will make it go slower or faster than the wind. I hear it is a really calm experience. I guess you hear something only if the wind direction changes, i.e. turbulence near the ground or thunderstorms (you do not want to be near one in a balloon), or wind direction change at the altitude you are in, or reaching an altitude with a different wind direction.

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    $\begingroup$ I've been on a balloon ride. I was not aware of any wind, but the balloon was traveling relative to the ground. $\endgroup$ – Patricia Shanahan Oct 9 '16 at 1:08
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    $\begingroup$ I've been on a balloon ride as well. The absence of wind was very noticeable - it was surprisingly like being indoors. Except for when we were using the burner it was extremely quiet, and you could hear things like animal sounds quite clearly from far below. I don't recall any gusts, turbulence or sudden changes in wind direction, probably because balloon flights only take place in very calm wind. $\endgroup$ – Nathaniel Oct 9 '16 at 3:28
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    $\begingroup$ @Nathaniel: Correct observation, that is why you don't see gliders and hot air balloons flying at the same time. The thermals which keep the gliders up will be a nightmare for the balloon pilot. With a strong negative thermal gradient (a precondition for thermals) the balloon is unstable in altitude. $\endgroup$ – Peter Kämpf Oct 9 '16 at 11:50
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Hypothetically, if you were on a flat plain with constant wind speed, and riding at wind speed, the only noises you'd hear are road noise from the chain, tires, gears and engine.

Normally, however, wind speeds are far lower than the motorcycle speeds where you start to really notice wind (less than 15 mph on average even in (most) really windy cities). And when you start getting 30+ mph winds, they tend to be rather gusty instead of constant. Also, high speed wind tends to run into nearby objects like trees, telephone poles, and even curbs, all of which makes wind noise.

I don't ride motorcycles, but I know in a car you can hear and feel the difference when riding relatively closely behind a semi trailer. It won't go away completely, but the semi is sucking a lot of the air forward, speeding it up, so the difference between you and the air around you is lower.

You can easily see the difference in air braking too. Come up behind a 50 mph semi at 70 mph on a multi-lane road. Let off the throttle completely, then change between the lane behind the semi and the other lane. You'll slow down a lot faster when you're in the other lane as a result of the pressure difference. You should be able to tangibly feel the difference on a motorcycle, since the wind hits you harder in the raw air. Or even just sticking your hand out the window.

You can also see this in fuel economy. Drive into the wind and you'll get worse economy than driving with the wind to your back. I once had 18 mpg one way and 29 mpg the other on a Dodge 2500 turbodiesel truck just west of El Paso, Texas. Likewise, you can get better fuel economy by riding behind a semi, although you need to stay far enough back that you're not constantly adjusting the throttle (though generally you're plenty far for that just by virtue of leaving a safe reaction distance between you).

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    $\begingroup$ Slight issue with your car story, the reason you have less wind effect is not due to the speed of the wind, it is down to the air being thinner due to the vehicle in front punching the air in front of it punching it away. $\endgroup$ – Topher Brink Oct 7 '16 at 10:29
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    $\begingroup$ @TopherBrink A reduction in pressure (thinner air) is only part of the slipstream effect. $\endgroup$ – JAB Oct 7 '16 at 15:22
  • $\begingroup$ > the only noises you'd hear are road noise from the chain, tires, gears and engine Wait, why noise produced by wind interacting with, say, trees will not be present? $\endgroup$ – Daerdemandt Oct 9 '16 at 14:42
  • $\begingroup$ @Daerdemandt: In this hypothetical plain, there are no trees, grass, etc. It's just a completely flat surface. I don't think there's anywhere on Earth that's really flat like that, but something like this might be close, as long as you're sufficiently far from the rocky outcrops. Of course, riding over the loose dirt is going to be noisy. $\endgroup$ – MichaelS Oct 9 '16 at 22:39
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If your ears moves continuously as per the wind the relative speed will be zero , and you wont hear it. But this case is ideal but not practical.

In reality, your movements wont be as smooth as wing. so there will be a relative difference (Non Zero) between both the vectors, your movement and wind.

Therefore, you will be able to feel it and hear it.

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Yes you would and no, you never do.

You never hear the wind per se, you hear only its interactions with physical objects. If you're moving in perfect unison with it, it is not interacting with you and so makes no noise from you. You will, however, hear it interact with other physical objects around you. (E.g. Trees, traffic cops, acorns left on the road by squirrels, etc...)

In the vacuum of space, you would not hear the space wind if your space bike was moving in unison with it. Unless, of course, a space squirrel left a space acorn near your path.

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When sailing against the wind, you feel it as much stronger because the true wind (wind you'd feel when standing still) and the wind caused because of your own motion will be added.

When sailing downwind these two will be subtracted and you'd only feel the difference between them.

The wind you feel is called the apparent wind.

When driving your motorcycle I guess you either travel faster than the wind or not exactly in the same direction, which causes the apparent wind you still feel.

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When you are moving in the same direction as the air with the same speed as the air, a circumstance also stated "with the same velocity as the air," the air is still in your frame of reference. Said another way: "in a coordinate frame oriented with you always at its origin, the air is not moving."

Therefore, you don't hear air moving around your ear. However, in the reference frame of a tree rustling in the wind or a sign that was blown over, the air certainly is moving. You would hear these phenomena unless your motorcycle is traveling faster than 1100ft/sec, which is the speed of sound in air, away from the sign, though not necessarily directly traveling directly away.

A fun digression is the question "whose reference frame is the absolute frame of reference?" "Relativity" is the answer to this. Relativity tells us the only absolute speed is the speed of light. All other observed motion and lack of motion is relative to some reference frame.

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You experience this when you sail exactly downwind. The quietness is quite strange since you hear so much more wind noise when tacking, it is also the fastest the boat will travel. One big disadvantage is you enjoy no cooling from the wind and you can quickly warm up on a hot day.

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protected by Qmechanic Oct 8 '16 at 10:30

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