Vertical wind shear, the difference of wind velocity between the ground and the top of the tropical cyclone, generally restricts tropical cyclone intensification. A tropical cyclone can become tilted by the wind shear so that that the circulation at the top is displaced from that near the ground. Sometimes the tropical cyclone is able to again become upright and intensify, but often such tilting is the beginning of the storm’s demise. A simple mathematical model predicts how much tilt the tropical cyclone will have based on how much cloudiness is within the eyewall as well as the structure of the wind outside the eyewall. This paper clarifies basic ways that a tropical cyclone can resist wind shear.
Tropical cyclones are better able to stay upright in vertical wind shear when there are lots of clouds in the eyewall.
Tropical cyclones are better able to stay upright in vertical wind shear when the wind’s spin quickly decays away from the eyewall.
A simple mathematical model confirms these findings.
There paper can be accessed at http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-14-0318.1.