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

In summary: The pressure gradient force is a force that acts on a fluid in the direction of the gradient of pressure. It is the result of the pressure difference between two points.
  • #1
Raptor112
46
0

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
 
Physics news on Phys.org
  • #2
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.)
 
  • #3
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?
 
  • #4
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?
 

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

1. What causes the extreme pressure in tornadoes?

The extreme pressure in tornadoes is caused by the rapid rotation of air within the vortex. As the air is pulled into the center of the vortex, it becomes compressed, leading to a decrease in pressure at the center of the tornado.

2. How does the pressure in a tornado compare to that of a hurricane?

The pressure in a tornado is typically much lower than that of a hurricane. While the average pressure in a hurricane is around 950 millibars, the pressure in a tornado can drop as low as 500 millibars. This is due to the smaller size and more intense winds of a tornado.

3. Can pressure changes in a tornado affect humans?

Yes, pressure changes in a tornado can have a significant impact on the human body. The rapid decrease in pressure can cause a feeling of pressure in the ears and can also lead to nausea, dizziness, and other symptoms similar to altitude sickness.

4. How does the pressure in a tornado affect structures?

The extreme pressure in a tornado can cause significant damage to structures. As the air rushes into the low-pressure center of the tornado, it can create a lifting force that can pick up and destroy buildings, trees, and other objects in its path.

5. Is there a way to measure the pressure in a tornado?

Yes, scientists use barometers to measure the pressure in a tornado. However, due to the chaotic and destructive nature of tornadoes, it can be difficult to obtain accurate measurements. Most measurements of tornado pressure are estimates based on the damage caused by the storm.

Back
Top