Re: Why is it that the centre of hurricane is calm?

Damage by hurricanes depends on the instant velocity of wind in a specific location within the hurricane. Instant velocity can be expressed as a product of angle velocity and radius (distance from its center). Since the radius in its center is zero, the velocity is also zero. Therefore, it is calm inside it. You can compare it to the wheel of a bike. Its instant velocity is zero in its center, however on the edge of the tire the instant velocity is quite high. This is the physical principle behind why the center is calm. How it originates is not well explained yet.

You may already know that many research groups are investigating why hurricanes and tornadoes form. To date, however, the mechanism is not well known. If we could find out, it would help warn people long enough in advance before it comes. For your information, tornadoes are classified on the Fujita scale (Fujita is a Japanese researcher) as F0 to F5, the F5 to be the most devastating. Hurricanes are classified by the Saffir-Simpson scale into 5 groups according to the wind velocity: weak, moderate, strong, very strong, and devastating.

If you would like to know more about it, don't hesitate to contact again.

Yours,
Robert