Climatology

Tropical Cyclone Development and Dissipation

A tropical cyclone is an intense low-pressure system formed over warm oceans, characterized by strong winds and heavy rainfall.

Stages of Development:

• Formative Stage (Tropical Disturbance)
  • Cluster of thunderstorms with weak circulation.
  • Sea surface temperature .
  • Sufficient Coriolis force (at least from equator).
• Intensification Stage (Tropical Depression)
  • Closed isobars develop.
  • Wind speed: .
  • Central pressure decreases.
• Mature Stage (Tropical Cyclone)
  • Well-developed eye at center.
  • Eyewall with strongest winds.
  • Wind speed .

Stages of Dissipation:

• Landfall: Moisture supply cuts off; weakening begins.
• Weakening Stage: Wind speeds decrease; structure disorganizes.
• Dissipation Stage: System becomes a remnant low-pressure area.

Necessary Conditions:

• Warm ocean water .
• Low vertical wind shear.
• High humidity.
• Pre-existing disturbance.

Energy Source:
Energy is derived from latent heat of condensation released by rising moist air.

Tropical Cyclone vs Temperate Cyclone

Tropical cyclones and Temperate cyclones (also called Extratropical or Mid-latitude cyclones) are two different types of atmospheric disturbances with distinct characteristics.

1. Based on Location and Formation

Tropical Cyclone:

• Forms between 5° and 30° latitudes in both hemispheres.
• Develops over warm tropical oceans.
• Requires sea surface temperature greater than .
• Does not form near the equator due to weak Coriolis force.

Temperate Cyclone:

• Forms between 30° and 60° latitudes.
• Develops over both land and sea.
• Forms along fronts (boundary between warm and cold air masses).

2. Based on Structure and Temperature

Tropical Cyclone:

• Warm-core system (center warmer than surroundings).
• No fronts associated.
• Has a well-defined eye at the center.
• Symmetrical circular shape.

Temperate Cyclone:

• Cold-core system.
• Associated with warm and cold fronts.
• No eye formation.
• Asymmetrical, wave-like structure.

3. Based on Wind Speed and Energy Source

Tropical Cyclone:

• Wind speed (can exceed 250 km/h).
• Energy derived from latent heat of condensation.
• Weakens over land or cold water.

Temperate Cyclone:

• Wind speed between .
• Energy derived from temperature contrast between air masses.
• Can persist over land.

Comparison Table:

Energy Representation:

For Tropical Cyclone:

For Temperate Cyclone: