What is the expression for pressure distribution in a rotating tornado?

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SUMMARY

The expression for pressure distribution in a rotating tornado can be derived using the hydrostatic equation, which states that the pressure gradient is equal to the product of air density and radial acceleration. Given a tornado with constant angular velocity ##\omega## and uniform temperature T, the pressure gradient can be expressed as ##\frac{dp}{dr} = \rho (\omega^2 r)##. To calculate the central pressure ##p_0##, one must apply the ideal gas law, which relates pressure, density, and temperature. For the conditions specified (T = 300 K, p = 100 kPa at 0.1 km), the density must be determined to find ##p_0##.

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  • Basic principles of atmospheric pressure and density relationships
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Homework Statement


A tornado rotates with constant angular velocity ##\omega## (i.e. like a solid object would rotate) and has
a uniform temperature T. Find an expression for the outward pressure distribution in terms of the central pressure ##p_0##. Use this to calculate ##p_0## given that T = 300 K and that at 0.1 km from the centre the atmospheric pressure p = 100 kPa and wind speed V = 100 m s-1.2. The attempt at a solution
Pressure gradient force =## -\frac{1}{\rho} \nabla p##
PV=NRT
 
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Raptor112 said:
PV=NRT
In my incomplete understanding, an 'equation of state' (such as PV=NRT) describes the properties of a system near equilibrium. I don't believe it can be (at least not naively) applied to more dynamic systems (such as a tornado). If anyone has more to say on this, please do; I like to learn as well.

Raptor112 said:
Pressure gradient force =## -\frac{1}{\rho} \nabla p##
Perhaps you mean "acceleration due to pressure gradient force" (check dimensions).
Anyway you want to model the tornado as having uniform angular velocity, so can you figure what the acceleration field (i.e. the left side of this quoted equation) is? (Use symmetry when choosing coordinates.)
 
Nathanael said:
Perhaps you mean "acceleration due to pressure gradient force" (check dimensions).
Pressure gradient (PG) = rate of change of pressure with distance which is from low to high pressure.PGF is from high to low pressure. But still don't see how you get the pressure distribution?
 
If a body is rotating with radial acceleration ##\omega^2r##, it is analogous to a gravitational force acting in the negative radial direction. So, from the hydrostatic equation,

$$\frac{dp}{dr}=\rho (\omega ^2r)$$

Of course the air density ##\rho## is a function of the pressure, so you need to take that into consideration using the ideal gas law. What is the equation for the density of an ideal gas in terms of the pressure, molecular weight, and temperature?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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