Richard,

On Fri, 17 Sep 2004 10:52:46 +1200, Richard.Prosser@Powerware.com wrote:

> Which raises another question.
> If you are standing in a strong wind, do local obstructions significantly
> effect measureed air pressure.? I would think that there could be a
> significant difference between the air pressure on the upwind side of a
> wall to the downwind side for example. - Or even standing in a strong wind
> may reduce the pressure slightly  due to the moving air = less pressure
> effect.

Yes the Bernoulli (and Venturi-) effect cause drop in pressure with increasing speed, assuming you're not 
actually in the airflow.  Point a sensor into wind and you get an increase in "pressure" sensed because of the 
airflow "pressing" on the sensor element.  Aircraft pitot tubes use this for measuring airspeed, comparing it 
against a "static" vent which is out of the airflow.

But if you're talking about a significant changes due to wind, it's unlikely to be great at human-survivable 
windspeeds if the sensor is shielded from direct airflow.

Cheers,


Howard Winter
St.Albans, England


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