Hurricanes are complex weather disturbances. Simple models are often used to help us understand the basics of complex flow patterns. This is a simple model of hurricane. A discussion of this simple model can be found in the book by R. Stull, Meteorology for Scientists and Engineers, published by Brooks/Cole. The model assumes that changes in the tangential velocity near the surface and the average tropospheric temperature are related to the change in pressure. The model also assumes:
  • The change in pressure is with respect to the pressure near the surface,
  • Temperature refers to the average temperature through the troposphere,
  • The tangential wind speed is with reference to the wind near the surface (To be classified a hurricane, the sustained winds must be at least. 32 m/s. The maximum tangential wind speed in this case is approximately 90 m/s.), and
  • The temperature difference is with respect to the environment.

    Use this simple model of hurricane to explore the relationships between the change in the hurricane central pressure and its environment. In addition to changing the central pressure, you can also change the distance from the center of the hurricane to the eye-wall. (Instructions)

    1. What happens to the temperature averaged over the depth of the hurricane, as the central pressure decreases. Explain why this would be so.
    2. Explain why the maximum tangential wind speed increases as the pressure between the center of the hurricane and the environment increases.
    3. This model does not allow for hurricane translation speeds. How will this affect the computed maximum tangential wind speed?

    Instructions (audio)

    You have control of two parameters, the pressure difference between the environment and the central pressure of the hurricane, and the radius of the eye-wall. As you change these parameters, you change the distribution of the tangential wind and temperature as a function of the distance from the hurricane eye. Changes are with reference to the average conditions of the environment.

    This applet was designed by S. Ackerman and T. Whittaker