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tropical depression
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3D cross-sectional illustration of a hurricane over ocean, showing cloud bands and vertical structure of storm systems.
Infographic showing Hurricane Katrina's path from its formation over the Bahamas to landfall in Florida and Louisiana, with a curved track across the southeastern U.S. It highlights nearly 1,400 lives lost, about $125 billion in damages, 62 tornadoes in 8 states, and a maximum storm surge of 26 to 28 feet in Mississippi. Flooded areas of New Orleans and storm categories at each location are also illustrated.
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tropical depression

meteorology
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3D cross-sectional illustration of a hurricane over ocean, showing cloud bands and vertical structure of storm systems.
How do cyclones form? Cyclones look like huge disks of clouds.

A tropical depression is a weather system characterized by a weak circulation of clouds and winds up to 38 km/h (23.6 mph). It is the initial stage in the development of a tropical cyclone. For a tropical depression to form and intensify, several conditions must be met: ocean surface temperatures must be at least 26.5°C (80°F) and at least 50 meters deep, there must be a pre-existing atmospheric circulation, and the atmosphere needs to cool sufficiently with height to support deep convective clouds. Additionally, the middle atmosphere should be humid, the system must be at least 500 km from the Equator, and wind speeds should change slowly with height. The primary fuel for these storms is the transfer of heat and water vapor from warm oceans to the atmosphere through evaporation.1

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2 Britannica Sources
  1. tropical cyclone - Formation
  2. tropical storm

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