Re: [Phys-l] Entrainment of oil in Hurricane?

[Brian Whatcott <betwys1@sbcglobal.net>]

There has been interest in standardizing the estimation of windspeed for 
two hundred years.   Noting observables was the approach used by 
Beaufort in his scale of wind force. Quite high on that scale: 
"hurricane force" winds - force 12- represented a sea state completely 
white with foam and spray, with reduced visibility. This is the state of 
affairs when wind speeds exceed  64 kt. I fid that local tornado 
warnings often feature winds considerably higher than that.   Like 
mariners, pilots find observables related to wind speed useful.   
Airfield wind socks usually indicate straight out at either 25 kt or 30 
kt  (I expect the FAA has a spec). For flyers, it is not so much the 
magnitude, but rather the direction of the wind vector that is of 
concern. A cross-wind landing can overstress landing gear.
A cross wind take off invites tire scrubbing and excursions off the 
runway. Aircraft have occasionally employed steerable main gear,
so that a heavy airplane might avoid the need to yaw straight on contact 
with the runway. Light aircraft sometimes use another strategy, the 
'crossed controls' method, with the upwind wing held down into the wind, 
and rudder applied so as to turn the plane away from the wind (source) 
direction, the net effect being a stable approach directed along the 
extended center line of the runway, and with the upwind main wheel 
touching first.
(Large aircraft may have less wing/nacelle  ground-clearance than even 
small airplanes, so it is not a viable option for them).

Still returning to the point, it is not so much the wind pressure that 
is troublesome - this is quite moderate in absolute terms. Rather it is 
the aggregate forces resulting from air drag in the high winds available.
The circulation is inward and upward into the eye of the tornado.
That upwardly directed drag force is what flies cats and dogs.

Brian W


John Clement wrote:
> But tornados also have high pressure which creates huge wind velocities.  So
> while suction (removal of pressure forces) will not do, air resistance can
> work quite well to elevate cows to great heights, and water is even easier
> when dispersed into droplets.
>
> There is even a well known case of a whole occupied house going aloft along
> with an old lady on a bicycle ;}
>
> John M. Clement
> Houston, TX
>
>   
> > Ah yes, I thought this might be the unspoken concern. It's a physics
> > thing - that water cannot be pumped up more than 33 feet in a suction
> > pump.   The engineer's way of suction-pumping water up more than twice
> > that Torricellian limit, is by adjusting the water-density that the pump
> > has to deal with.
> >
> >     
>
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