Tropical cyclones are intense low-pressure synoptic systems that develop over warm tropical oceans through convective thermodynamic processes. Their genesis requires sea surface temperatures exceeding 26.5°C across a 50-metre depth, sufficient Coriolis force (occurring beyond 5° latitude from the equator), low vertical wind shear, and high mid-tropospheric humidity. Structurally, a mature cyclone comprises a central cloud-free 'eye' characterized by descending air and minimum barometric pressure, surrounded by the 'eyewall' containing intense cumulonimbus convection and peak wind velocities. In the North Indian Ocean basin, the Bay of Bengal witnesses approximately four times more cyclones than the Arabian Sea, driven by higher sea surface temperatures, low salinity surface stratification, and remnant depressions migrating from the South China Sea. The India Meteorological Department (IMD) classifies these disturbances by sustained wind speeds: Cyclonic Storm (62–88 km/h), Severe Cyclonic Storm (89–117 km/h), Very Severe Cyclonic Storm (118–166 km/h), Extremely Severe Cyclonic Storm (167–221 km/h), and Super Cyclonic Storm (≥222 km/h), exemplified by the catastrophic 1999 Odisha Super Cyclone. Cyclone naming is coordinated by the WMO/ESCAP Panel on Tropical Cyclones, while post-2005 disaster governance is mandated under the Disaster Management Act, 2005.
High-yield conceptual summaries for competitive exams and rapid revision.
Tropical cyclogenesis requires sea surface temperatures of at least 26.5°C, high humidity, low vertical wind shear, and Coriolis force.
A mature cyclone features a central low-pressure calm eye surrounded by a high-velocity eyewall exhibiting maximum precipitation and wind speeds.
The Bay of Bengal experiences significantly higher cyclone frequency and intensity than the Arabian Sea due to warmer waters and upper-ocean stratification.
The IMD classifies storms into categories from Depression to Super Cyclonic Storm (sustained wind speeds of 222 km/h and above).
Cyclones in the North Indian Ocean are named sequentially by the WMO/ESCAP panel, with response coordinated under the Disaster Management Act, 2005.
Showing 25 Curated Questions81 Total in Bank
1ID: GK-DMGT-00034
easyCyclones, IMD Alerts, GLOFs & Urban Floods
What is the roughly circular, calm, cloudless, and lowest-pressure central region of a mature tropical cyclone called?
Verified Explanation
The 'Eye' is a roughly circular area of comparatively light winds, subsiding air, and fair weather found at the exact center of a severe tropical cyclone. It is surrounded by the 'Eyewall', which contains the cyclone's strongest winds and most violent thunderstorms.
2ID: GK-DMGT-00039
mediumCyclones, IMD Alerts, GLOFs & Urban Floods
According to the IMD tropical cyclone classification scale, what minimum sustained wind speed qualifies a system as a 'Super Cyclonic Storm'?
Verified Explanation
In the North Indian Ocean basin, the IMD classifies a tropical cyclone as a 'Super Cyclonic Storm' when its maximum sustained 3-minute surface winds reach or exceed 222 km/h (120 knots or 61.7 m/s).
3ID: GK-DMGT-00094
easyCyclones, IMD Alerts, GLOFs & Urban Floods
What is the meteorological term for the ring of towering cumulonimbus clouds and strongest winds immediately surrounding the calm eye of a tropical cyclone?
Verified Explanation
The Eye Wall is the dense ring of intense thunderstorms surrounding the cyclone's eye. It contains the lowest pressure gradients, highest sustained wind velocities, and most torrential precipitation of the entire cyclonic system.
4ID: GK-DMGT-00098
mediumCyclones, IMD Alerts, GLOFs & Urban Floods
In the IMD's 4-stage cyclone warning mechanism, which bulletin is known as 'Pre-Cyclone Watch' and issued at least 72 hours prior to the commencement of adverse weather?
Verified Explanation
Stage-1 is 'Pre-Cyclone Watch' issued 72 hours in advance. Stage-2 is 'Cyclone Alert' (48 hours), Stage-3 is 'Cyclone Warning' (24 hours), and Stage-4 is 'Post-Landfall Outlook' issued 12 hours before expected landfall.
5ID: GK-DMGT-00100
mediumCyclones, IMD Alerts, GLOFs & Urban Floods
Which World Bank-assisted flagship national project was launched by the Government of India to construct Multipurpose Cyclone Shelters (MPCS) and underground electricity cabling in vulnerable coastal states?
Verified Explanation
The National Cyclone Risk Mitigation Project (NCRMP), funded by the World Bank and implemented by NDMA in coordination with coastal states, builds early warning dissemination systems (EWDS), multipurpose cyclone shelters (MPCS), and cyclone-resilient infrastructure.
6ID: GK-DMGT-00107
hardCyclones, IMD Alerts, GLOFs & Urban Floods
In the nomenclature of tropical cyclones over the North Indian Ocean basin, which rule governs the retirement of a cyclone name?
Verified Explanation
Under WMO/ESCAP guidelines, if a cyclone causes exceptionally heavy loss of life and property, its name is permanently retired from the rotating panel list to prevent confusion and out of respect for disaster victims, and is replaced by a new name.
7ID: GK-DMGT-00110
hardCyclones, IMD Alerts, GLOFs & Urban Floods
Why was the evacuation of 1.4 million people in Odisha ahead of Cyclone Fani (May 2019) hailed globally by the United Nations Office for Disaster Risk Reduction (UNDRR)?
Verified Explanation
Cyclone Fani was a Category 5-equivalent Extremely Severe Cyclonic Storm. Odisha's massive pre-emptive evacuation of 1.4 million people within 48 hours into 4,000+ cyclone shelters, enabled by IMD's precise forecasts, kept human casualties below 50, setting a global benchmark in DRR.
8ID: GK-DMGT-00152
easyCyclones, IMD Alerts, GLOFs & Urban Floods
In the IMD 4-stage cyclone warning mechanism, which specific bulletin is known as 'Cyclone Warning' (Orange message) and issued at least 24 hours in advance?
Verified Explanation
Stage-3 is designated as the 'Cyclone Warning' (Orange bulletin) and is issued at least 24 hours in advance of the expected landfall, giving specific details about the expected place, time, wind speeds, and storm surge height along the coast.
9ID: GK-DMGT-00156
easyCyclones, IMD Alerts, GLOFs & Urban Floods
What is the dense, circular shield of thick cirrus and deep convective clouds that covers the eye and inner core of a mature tropical cyclone on infrared satellite imagery called?
Verified Explanation
The Central Dense Overcast (CDO) is the large, compact, roughly circular shield of cold cloud tops that develops over the center of a strong tropical cyclone. The pattern and temperature of the CDO are key components in the Dvorak technique for estimating cyclone intensity.
10ID: GK-DMGT-00158
mediumCyclones, IMD Alerts, GLOFs & Urban Floods
What quantitative method developed by Vernon Dvorak is used by the IMD and tropical cyclone tracking centers to estimate tropical cyclone intensity from enhanced infrared and visible satellite imagery?
Verified Explanation
The Dvorak Technique is a standardized subjective satellite interpretation method that assigns 'T-numbers' (ranging from T1.0 to T8.0) based on cloud patterns, central dense overcast curvature, eye definition, and cloud-top brightness temperatures to estimate cyclone wind speeds and central pressure.
11ID: GK-DMGT-00211
easyCyclones, IMD Alerts, GLOFs & Urban Floods
What structural zone at the geometric center of a mature tropical cyclone is characterized by calm winds, clear skies, and lowest surface barometric pressure?
Verified Explanation
The 'Eye' is a roughly circular area of comparatively light winds and fair weather found at the center of a mature tropical cyclone. It contains the lowest barometric surface pressure of the storm and is encircled by the violent eyewall.
12ID: GK-DMGT-00215
easyCyclones, IMD Alerts, GLOFs & Urban Floods
Which part of a tropical cyclone surrounding the calm central eye experiences the most violent destructive winds and heaviest torrential downpours?
Verified Explanation
The Eyewall is the dense ring of deep convective cumulonimbus clouds immediately surrounding the eye of a tropical cyclone. It contains the storm's most intense vertical updrafts, maximum sustained surface winds, and heaviest precipitation.
13ID: GK-DMGT-00218
mediumCyclones, IMD Alerts, GLOFs & Urban Floods
Which oceanographic parameter, measuring the integrated heat content from the sea surface down to the 26°C isotherm, is a vital predictor for rapid cyclone intensification?
Verified Explanation
Tropical Cyclone Heat Potential (TCHP) represents the upper-ocean heat content from the surface to the depth of the 26°C isotherm. High TCHP (> 77 kJ/cm^2) prevents cyclonic wind-induced cold water upwelling, sustaining rapid cyclone intensification.
14ID: GK-DMGT-00219
mediumCyclones, IMD Alerts, GLOFs & Urban Floods
In tropical cyclone forecasting, 'Rapid Intensification' (RI) is meteorologically defined as an increase in maximum sustained surface wind speed of at least what threshold over a 24-hour period?
Verified Explanation
The World Meteorological Organization (WMO) and IMD define Rapid Intensification (RI) of a tropical cyclone as an increase in maximum sustained surface wind speed of at least 30 knots (approx 55 km/h or 15.4 m/s) within a 24-hour time window.
15ID: GK-DMGT-00224
hardCyclones, IMD Alerts, GLOFs & Urban Floods
In dynamic meteorology, what causes a tropical cyclone in the Northern Hemisphere to naturally drift poleward and westward independently of environmental steering winds?
Verified Explanation
Beta drift is the autonomous poleward and westward propagation of a tropical cyclone vortex caused by the advection of Earth's planetary vorticity (the 'beta effect'). The cyclone's cyclonic circulation advects higher planetary vorticity from the north southward on its west side, setting up secondary gyres.
16ID: GK-DMGT-00275
easyCyclones, IMD Alerts, GLOFs & Urban Floods
Under the IMD cyclone classification system, what is the maximum sustained wind speed threshold for a cyclonic system to be classified as a 'Super Cyclonic Storm'?
Verified Explanation
Under the IMD classification for the North Indian Ocean, a tropical cyclone is designated as a 'Super Cyclonic Storm' when its maximum sustained 3-minute surface wind speed reaches or exceeds 120 knots (222 km/h). This represents the highest intensity category on the IMD storm scale.
17ID: GK-DMGT-00278
mediumCyclones, IMD Alerts, GLOFs & Urban Floods
In the IMD's 4-stage cyclone warning protocol, what is the 'Stage 2' warning issued at least 48 hours in advance of expected adverse weather called?
Verified Explanation
The IMD's 4-stage cyclone warning system consists of: Stage 1 (Pre-Cyclone Watch, 72 hours prior), Stage 2 (Cyclone Alert / Yellow message, at least 48 hours prior), Stage 3 (Cyclone Warning / Orange message, at least 24 hours prior), and Stage 4 (Post-Landfall Outlook / Red message, at least 12 hours prior). The Cyclone Alert color code Yellow signifies 'Be Updated' for coastal disaster management authorities.
18ID: GK-DMGT-00336
easyCyclones, Floods & Glacial Lake Outburst Floods
Which major multilateral financial institution funded the National Cyclone Risk Mitigation Project (NCRMP) executed by NDMA to construct multipurpose cyclone shelters and coastal early warning networks?
Verified Explanation
The National Cyclone Risk Mitigation Project (NCRMP) is an initiative implemented by the NDMA with financial assistance from the World Bank to reduce the vulnerability of coastal communities across Indian maritime states.
19ID: GK-DMGT-00338
mediumCyclones, Floods & Glacial Lake Outburst Floods
In the IMD's 4-stage cyclone warning mechanism, which specific advisory is issued at least 72 hours in advance when a depression develops over oceanic areas likely to affect coastal belts?
Verified Explanation
The first stage of IMD's 4-stage cyclone warning system is the 'Pre-Cyclone Watch', issued at least 72 hours prior to the commencement of adverse weather to inform the Cabinet Secretary and senior administrators about cyclonic development.
20ID: GK-DMGT-00391
easyCyclones, Floods & Glacial Lake Outburst Floods
Which centrally sponsored project implemented by NDMA with World Bank financial assistance aims to construct multi-purpose cyclone shelters and early warning systems across vulnerable coastal states?
Verified Explanation
The National Cyclone Risk Mitigation Project (NCRMP) is executed by the National Disaster Management Authority (NDMA) with World Bank assistance. It constructs multi-purpose cyclone shelters, access roads, underground cabling, and early warning dissemination systems in coastal states.
21ID: GK-DMGT-00394
easyCyclones, Floods & Glacial Lake Outburst Floods
Which physical characteristic is uniquely observed within the 'Eye' of a mature tropical cyclone?
Verified Explanation
The 'Eye' of a mature tropical cyclone is a roughly circular region of calm weather, characterized by light winds, subsiding warm air, clear or partly cloudy skies, and the lowest barometric pressure of the entire cyclone system. In contrast, the surrounding 'Eyewall' contains the most violent winds.
22ID: GK-DMGT-00406
hardCyclones, Floods & Glacial Lake Outburst Floods
What peak sustained surface wind speed was recorded during the landmark 1999 Odisha Super Cyclone (05B), which triggered India's comprehensive transformation toward institutional disaster management?
Verified Explanation
The 1999 Odisha Super Cyclone made landfall near Paradip with estimated maximum sustained surface winds of 260 km/h (gusts up to 300 km/h) and a catastrophic storm surge of 7–9 meters, leading to the enactment of state disaster bodies (OSDMA) and eventually the national DM Act 2005.
23ID: GK-DMGT-00453
easyCyclones, Floods & Glacial Lake Outburst Floods
Under the cyclone classification scale utilized by the India Meteorological Department (IMD), what sustained surface wind speed qualifies a tropical system as a 'Super Cyclonic Storm'?
Verified Explanation
Under the IMD classification for the North Indian Ocean, a 'Super Cyclonic Storm' is the highest category of tropical cyclone, characterized by maximum sustained 3-minute surface wind speeds of 120 knots (222 km/h) or more, as seen in the 1999 Odisha Super Cyclone and Cyclone Amphan (2020).
24ID: GK-DMGT-00457
easyCyclones, Floods & Glacial Lake Outburst Floods
Which major externally aided initiative was initiated by the Ministry of Home Affairs and NDMA with World Bank funding to construct multi-purpose cyclone shelters and underground electrical cabling along vulnerable Indian coasts?
Verified Explanation
The National Cyclone Risk Mitigation Project (NCRMP) is a flagship initiative implemented by NDMA with financial assistance from the World Bank. It covers coastal states (e.g. Odisha, Andhra Pradesh, West Bengal, Tamil Nadu, Gujarat) to build multi-purpose cyclone shelters, install early warning dissemination systems, and construct underground electrical cables to prevent power grid collapse.
25ID: GK-DMGT-00466
hardCyclones, Floods & Glacial Lake Outburst Floods
In the IMD's 4-stage cyclone warning system, which stage is issued at least 24 hours in advance of expected landfall, indicating the anticipated landfall point and associated gale winds?
Verified Explanation
IMD's 4-stage warning system comprises: Stage 1 (Pre-Cyclone Watch, 72h prior), Stage 2 (Cyclone Alert, Yellow colour code, issued at least 48h in advance), Stage 3 (Cyclone Warning, Orange colour code, issued at least 24h in advance detailing landfall location and storm surge), and Stage 4 (Post-Landfall Outlook, Red colour code, issued at least 12h in advance).