# wind vs air resistance

I'm wondering which offers more resistance: pulling an object at some speed through air, or holding the object steady against wind at the same speed.

I think initially people would think same resistance.

Then I thought that the air that is flowing has probably been compressed under it's own speed (or rather, in order to get to it's speed), and therefore offers more resistance. Also, the wind may be colder (thus denser) if it's the wind I'm used to, but disregarding temperature influence, do you think that my theory is correct? Can we quantify the resistance gained by windspeed?

• Wind isn't colder. It only feels colder due to evaporation. IMO, the answer to this question depends upon the method of generation of wind due to the pressure issue. Commented Mar 17, 2012 at 5:05
• Ah true. I'm thinking of the usual method of wind generation. Commented Mar 17, 2012 at 6:28

One might say, to be specific: a perfect wind with constant density $\rho$, pressure $P$, velocity $v$ produces the same effect on a body at rest, as on a body, which is moving with velocity $v$ in a still medium of pressure $P$ and density $\rho$. Should you want to specify any other physical parameters, they should be taken the same for the media in both cases.
The statement is guaranteed to be true by galilean invarince. You see a body moving with velocity $v$ in a medium, you start to move yourself with velocity $v$, and you see the body standing still and a wind blowing with velocity $v$. The same physics - just a different reference frame.