# The wheels on the bus go round and round...

Well, my question isn’t about the wheels of the bus. I am posing a question to you all: Why does a bus with some open windows (scattered from front to back) going forward with enough momentum create air inside the bus…going from back to front?

I can only think this is from air getting in the front of the bus gets pushed backwards since the bus is going forwards, and the air in the back gets pushed forward from the new air, but then I never feel air going the right way in the bus. Help?

Snappy

::puts it back on the top so somebody can answer it:: Maybe I should ask Cecil if I don’t get an answer. I know little about aerodynamics inside buses…does anybody have even a guess involving aliens and/or giant mutated crabs terrorizing Iceland?

Snappy

I have a wild guess:
The air actually acts as you would expect, but only nearest the windows. In a column in the middle, it goes back to front, since all the air going front to back near the windows creates high pressure in a spot at the very back of the central column. So there is a pair of eddys, with a central current against two turbulent tributaries.
Why would you feel the central column more strongly than the more intuitive window zones? Another wild guess: the window zones are already quite turbulent. You feel air hitting you from all directions. The average vector of the air is backwards, but it’s obscured by the large number of small forces (open windows) not quite acting together.
In contrast, the central air column moving in the counterintuitive direction is the sum of all those forces, with the turbulence tending to cancel itself out. The only thing really acting on this central column is high pressure at the rear and low pressure near the driver. So it’s much easier to sense as a steady breeze.

I don’t want to make people think like me, I want them to think like me of their own free will.

## Let me give my WAP. Good ol’ Bernoulli. At the front of the bus, the air flow is fairly laminer across the open windows, so there is actually a suction (faster air=lower pressure), the rear window are exposed to more turbulent air, so higher pressure, and air can be sucked in.

No time to look words up, misspellings are all mine.

Good answer ,boris, at least it made more sense than the question.I was unaware that our atmosphere is actually created inside buses. Now I understand the question to be ," why does air in a bus move the direction it does?"Air does not ALWAYS move towards the front. Or is that what you are claiming,snap? That hasn’t been my experience. Forget about momentum affecting the air flow. Thin got it right. Picture a north bound bus with a wind from the west. Lots of low pressure on the east. Open a window in the front east and one rear west. Air goes forward. Front west rear east, backwards. How many windows are open where are they? It could get complicated. I will admit that the air moves forward more often. But that is easily explained. As the driver,Mr Bernoulli, asks people to “step to the rear please,” the mass of humanity just pushes the air forward.

“Pardon me while I have a strange interlude.”-Marx

I haven’t ridden on too many buses, sorry for the…obscurity I sent out. I ride the bus from school back home. Some days it is not windy and this happens, other times it is windy, and from different directions (and the bus changing directions when the wind doesn’t). It happens every time as far as I can tell. The bus drives through a semi-open plain most of the time, only bordered by a few trees and the prison buildings.

Whee! A prison a mile between my house and my school. And people escaping all the time.

But anyway, this happens every single time I ride the bus, and I think Boris’ answer sounds right. Thank you Boris.

Snappy

I guess I’ve been on the wrong bus!

I’ve ridden the school bus, the camp bus, and the public MTA bus with windows open. I can never recall the air ever going in the reverse direction. The air will blow my hair back or side-to side during a strong cross breeze, but never have I experienced air from the back!

Yet, many of you have experienced this?
Curious!

I’d rather have a bottle in front of me than a frontal lobotomy - Hawkeye 4077th