Cyclones are climatological phenomenon in which a low pressure core is surrounded by high pressure exterior. They move at a varied speed over the ocean and on landfall their speed decreases considerably and it dissipates. On the basis of the intensity (closely related to its velocity), the system is as:
| Name | Wind Speed | Structure | Other Feature |
| Tropical Disturbance | Negligible | Slightly circular, with winds moving in from all directions. | Also called ‘low pressure system |
| Tropical Depression | Less than 17 m/sec
Less than 33 knots
Less than 38 mph
Less than 62 kmph | Organized system of thunderstorms and well defined circular motion of winds, but no eye formation. | |
| Tropical Storms | 17 - 33 m/second
34-63 knots
39-73 mph
62-117 kmph | Well-defined surface circulation. Definite cyclonic shape begins to form, eye is usually not present. | Assigned name at this stage, hence the stage is also called named storm |
| Hurricanes/ Typhoons, etc. | Average speed is more than 120 km per hour. | Eye formation with clear eye walls. | Strongest winds and thunderstorms.
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