Summary
Highlights
A tropical cyclone's life cycle involves three basic stages: origin, mature, and dissipation. These stages are continuous, not distinct, and a cyclone's strength can fluctuate, allowing it to re-strengthen after weakening.
The formation of a cyclone requires specific conditions: a large, still, warm ocean area with a surface temperature exceeding 26.5 degrees Celsius for an extended period, which creates a body of warm air, and low-altitude winds.
As air warms over the ocean, it expands, becomes lighter, and rises. Other local winds replace this rising air, which then also warms and rises. This rising air, laden with evaporated moisture, cools and condenses at about 10 kilometers in the troposphere, forming huge clouds. More warm air rushes in and rises, further feeding the cloud formation.
Condensation releases latent heat energy, powering the cyclone and creating a self-sustaining heat cycle. This energy release allows clouds to grow to 12-15 kilometers high. The Coriolis effect, caused by the Earth's rotation, makes rising air currents spiral around the cyclone's center.
During the mature stage, the eye of the storm forms. As air rises and cools, some dense air descends to create the clear, still eye, while the eye wall features the strongest winds, behaving like a whirling cylinder. Cyclones rotate clockwise in the Southern Hemisphere and anti-clockwise in the Northern Hemisphere.
The lowest air pressure in a tropical cyclone is found at its center, typically 950 millibars or less, significantly lower than the average surface air pressure of 1010 millibars. A larger pressure difference indicates a stronger wind force. Typhoon Ida, which hit the Philippines in 1958, recorded one of the lowest pressures at 877 millibars, with winds reaching 300 kilometers per hour.
Once formed, a cyclone's movement, or track, is driven by global wind circulation, moving away from its source. It continues to enlarge as warm ocean waters provide it with heat and moisture.