IAS NOVA Interactive Atlas
Tropical Cyclones of the World
Trace the warm-ocean storm belts of Earth—from Atlantic hurricanes and Pacific typhoons to Bay of Bengal cyclones, coral-sea storms and Southern Ocean-free tropical margins.
Definition
A tropical cyclone is a warm-core, non-frontal low-pressure system that develops over tropical or subtropical oceans, draws energy from latent heat released by deep convection, and organizes into rotating wind circulation around a calm or partly calm eye. This atlas explains the global distribution of hurricanes, typhoons and cyclones through basin geography, seasonal windows, sea-surface conditions, tracks, hazards and major regional contrasts.
Learn with the map: Open it in FULL SCREEN, choose a cyclone basin or feature type, and hover, tap or use the Index to compare formation zones, tracks, seasons, naming regions and major hazards.
Plate 01 · Core Idea
Why tropical cyclones form where they do
Tropical cyclones are not randomly distributed. They cluster over warm tropical oceans where sea-surface temperatures are usually above 26.5°C, the atmosphere is moist through a deep layer, and vertical wind shear is low enough to let convection organize around a central low. They generally form between about 5° and 20° latitude because the Coriolis force is too weak very near the Equator to generate the rotation needed for a closed cyclonic circulation.
They strengthen by drawing energy from warm water and from the release of latent heat as moist air rises, cools and condenses. This is why cyclone intensity is closely tied to ocean heat content, slow storm movement over warm water, and the absence of strong upper-level winds that can tilt and disrupt the storm column.
Plate 02 · Formation Controls
Six controls every student should know
Warm ocean water
Tropical cyclones need warm water, typically at least 26.5°C over a sufficiently deep layer. If only the surface is warm, strong winds can churn cooler water upward and weaken the storm. Deep ocean heat content therefore matters as much as the sea-surface temperature shown on a simple map.
Plate 03 · Global Belts
Global basin structure
Plate 04 · Classification
Storm structure and intensity
Main parts of a tropical cyclone
- Eye: relatively calm centre with descending air.
- Eyewall: ring of strongest winds and heaviest rain.
- Rainbands: spiral bands of intense convection.
- Warm core: the storm is warmer aloft than the surrounding environment.
Hazards at landfall
- Storm surge and coastal inundation.
- Extreme rainfall and river flooding.
- Destructive winds and infrastructure damage.
- Landslides in steep humid terrains.
| Term | Where used | Meaning | Geographical note |
|---|---|---|---|
| Hurricane | North Atlantic and Eastern North Pacific | Tropical cyclone reaching threshold wind speed in those basins | Same type of storm as a typhoon or cyclone; only the regional name changes. |
| Typhoon | Western North Pacific | Regional name for intense tropical cyclones | Most active basin of the world. |
| Cyclone | North Indian, South Indian, Australian and South Pacific regions | Regional name for the same storm family | Bay of Bengal cyclones are especially notorious for storm surges. |
| Tropical depression / storm | All basins | Lower stages before full cyclone intensity | Early warning and naming conventions differ by basin. |
Plate 05 · Tracks and Seasons
Why cyclone tracks curve
In their early stage, tropical cyclones are usually steered westward by the trade winds. As they move poleward toward the subtropical margins, many curve or recurve eastward under the influence of the westerlies. This is why Atlantic hurricanes often move westward across the tropical Atlantic before turning toward the north or northeast near the western Atlantic, while many western Pacific typhoons first head west or northwest and later recurve toward Japan or the open Pacific.
Seasonality reflects ocean heating and atmospheric conditions. Northern Hemisphere basins peak from June to November, whereas Southern Hemisphere basins generally peak from November to April. The North Indian Ocean shows two preferred periods—before and after the core monsoon—because monsoon shear suppresses storm development during part of the summer season.
Plate 06 · India Focus
North Indian Ocean and the Bay of Bengal
The Bay of Bengal is one of the most deadly cyclone sub-regions in the world. Several geographical reasons explain this: warm waters, a funnel-shaped northern bay, shallow coastal shelves, densely populated low-lying deltas and estuaries, and extensive vulnerable coasts in eastern India and Bangladesh. Even when cyclones are not the strongest globally, storm surge and flooding can produce catastrophic loss.
The Arabian Sea traditionally produced fewer intense storms than the Bay of Bengal, but warming waters have increased interest in its changing cyclone behaviour. Western India, Pakistan, Oman and Yemen may all be affected under suitable track conditions.
Plate 07 · Ocean-Atmosphere Links
ENSO, climate change and cyclone geography
El Niño and La Niña affect tropical cyclone distribution by changing vertical wind shear, sea-surface temperatures and large-scale circulation. El Niño often suppresses Atlantic cyclone activity by increasing wind shear, while some Pacific basins become more favourable. La Niña often supports a more active Atlantic season.
Climate change does not mean that every basin will simply produce more cyclones every year. Instead, geography students should focus on nuanced changes: warmer oceans, heavier rainfall rates, possible shifts in the proportion of very intense storms, changing storm tracks in some regions, and rising sea level that worsens the impact of storm surges even without a major increase in storm numbers.
Plate 08 · Compare
Basin comparison table
| Basin | Regional name | Main season | General track | Key vulnerable coasts |
|---|---|---|---|---|
| North Atlantic | Hurricane | Jun–Nov | Westward then recurving north/east | Caribbean, Gulf of Mexico, southeast USA |
| Eastern North Pacific | Hurricane | May–Nov | West-northwest; many remain offshore | Western Mexico, Baja California |
| Western North Pacific | Typhoon | All year, peak Jul–Oct | West/northwest then recurving | Philippines, China, Taiwan, Japan, Vietnam |
| North Indian Ocean | Cyclone | Apr–Jun and Oct–Dec | Northward, northwestward or northeastward | Odisha, Andhra coast, West Bengal, Bangladesh, Myanmar |
| South Indian Ocean | Cyclone | Nov–Apr | West/southwest then southeast recurvature | Madagascar, Mozambique, Mascarene region |
| Australian region | Cyclone | Nov–Apr | West or southwest, some curve poleward | Northwest and northeast Australia |
| South Pacific | Cyclone | Nov–Apr | West/southwest then southeastward | Fiji, Vanuatu, Tonga, New Caledonia, New Zealand fringe |
Plate 09 · Revision
Complete reference list
Necessary conditions
Warm water, deep moisture, low vertical wind shear, sufficient Coriolis force, and a pre-existing low-level disturbance are the classic conditions.
Main cyclone belts
Most storms form between 5° and 20°/25° latitude in the Atlantic, Pacific and Indian Ocean basins, with very few near the Equator and very few in the South Atlantic.
Track logic
Initial westward movement under trade winds, later recurvature under the westerlies as storms move poleward.
Most dangerous impacts
Storm surge is often the deadliest coastal hazard. Heavy rainfall, river floods, landslides and extreme winds are additional major dangers.
Plate 10 · Test Yourself
Interactive MCQs
Plate 11 · FAQs
Frequently asked questions
What is the difference between a hurricane, typhoon and cyclone?
They are the same type of storm: a tropical cyclone. The name changes by region. “Hurricane” is used in the Atlantic and Eastern North Pacific, “typhoon” in the Western North Pacific, and “cyclone” in the Indian Ocean and South Pacific/Australian regions.
Why are there very few cyclones in the South Atlantic?
Conditions are usually less favourable there because vertical wind shear is often high and sea-surface and atmospheric patterns are less supportive than in the major cyclone basins.
Why do cyclones weaken after landfall?
They lose access to warm ocean energy and encounter greater surface friction. Mountainous terrain can further disrupt the circulation, though heavy rainfall hazards may continue inland.
Why is the Bay of Bengal more dangerous than the Arabian Sea?
The Bay of Bengal combines warm water, funnel-shaped northern coasts, shallow shelves, low-lying deltas and dense population, making storm surges exceptionally dangerous.
How does ENSO affect tropical cyclones?
ENSO modifies sea-surface temperatures, wind shear and large-scale circulation. El Niño often suppresses Atlantic activity and shifts favourability toward parts of the Pacific, while La Niña often supports a more active Atlantic season.
Plate 12 · Sources
Sources and further reading
- WMO resources on tropical cyclone terminology and warning regions.
- NOAA and National Hurricane Center educational material on tropical cyclone structure, hazards and Atlantic/Eastern Pacific seasons.
- JTWC and RSMC/TCWC regional material for Indian Ocean, Western Pacific and Southern Hemisphere basins.
- IMD guidance on North Indian Ocean cyclones, naming and warning services.
- Standard climatology and physical geography texts for warm-core storm dynamics, steering winds and storm surge geography.
