Cyclone

1. Low-Pressure System

A low-pressure system is an area where the atmospheric pressure is lower than its surroundings. These systems are associated with rising warm air, which leads to cloud formation and precipitation. They are the primary drivers of weather disturbances like cyclones and storms.

Concept: Warm air rises, creating a region of lower pressure at the surface. As air converges to fill this void, it starts to rotate due to the Coriolis effect.
Example: A monsoon low-pressure system forming over the Bay of Bengal, leading to heavy rains in eastern India.

2. Depression

A depression is a more developed form of a low-pressure system with a well-defined circulation. It brings moderate to heavy rainfall and gusty winds.

Concept: When a low-pressure system intensifies with wind speeds between 31-49 km/h, it is classified as a depression.
Example: The depression over the Arabian Sea that causes heavy rainfall in Mumbai during the monsoon season.

3. Deep Depression

A deep depression is a further intensification of a depression with stronger winds and heavier rainfall.

Concept: A depression becomes a deep depression when wind speeds increase to 50-61 km/h. This stage is a precursor to a tropical storm or cyclone.
Example: A deep depression forming over the Bay of Bengal, later developing into Cyclone Yaas in 2021.

4. Cyclone

A cyclone is a large-scale air mass that rotates around a strong center of low atmospheric pressure. It is classified into different categories based on wind speed.

Concept: A cyclone forms when a deep depression further intensifies, with wind speeds exceeding 62 km/h. Warm ocean waters provide energy, causing rapid intensification.
Types of Cyclones:
- Tropical Cyclones: Form over warm ocean waters (e.g., Cyclone Amphan in 2020).
- Extratropical Cyclones: Occur outside tropical regions and are associated with frontal systems (e.g., Nor'easters in the U.S.).

5. Storm

A storm is a general term for a disturbed state of the atmosphere that can bring strong winds, heavy rain, thunder, lightning, and sometimes snow.

Concept: When wind speeds reach 62-88 km/h, the system is called a "Cyclonic Storm." If it intensifies further, it may become a Severe Cyclonic Storm (89-117 km/h) or even a Super Cyclone (>222 km/h).
Example: Cyclone Fani (2019) was classified as an Extremely Severe Cyclonic Storm with wind speeds exceeding 250 km/h, causing significant destruction in Odisha, India.

Wind Speed Classifications

System Type	Wind Speed (km/h)
Low Pressure	< 31
Depression	31-49
Deep Depression	50-61
Cyclonic Storm	62-88
Severe Cyclonic Storm	89-117
Very Severe Cyclonic Storm	118-165
Extremely Severe Cyclonic Storm	166-221
Super Cyclone	> 222

Comments

Types of Remote Sensing

Remote Sensing means collecting information about the Earth's surface without touching it , usually using satellites, aircraft, or drones . There are different types of remote sensing based on the energy source and the wavelength region used. 🛰️ 1. Active Remote Sensing 📘 Concept: In active remote sensing , the sensor sends out its own energy (like a signal or pulse) to the Earth's surface. The sensor then records the reflected or backscattered energy that comes back from the surface. ⚙️ Key Terminology: Transmitter: sends energy (like a radar pulse or laser beam). Receiver: detects the energy that bounces back. Backscatter: energy that is reflected back to the sensor. 📊 Examples of Active Sensors: RADAR (Radio Detection and Ranging): Uses microwave signals to detect surface roughness, soil moisture, or ocean waves. LiDAR (Light Detection and Ranging): Uses laser light (near-infrared) to measure elevation, vegetation...

geostationary and sun-synchronous

Orbital characteristics of Remote sensing satellite geostationary and sun-synchronous Orbits in Remote Sensing Orbit = the path a satellite follows around the Earth. The orbit determines what part of Earth the satellite can see , how often it revisits , and what applications it is good for . Remote sensing satellites mainly use two standard orbits : Geostationary Orbit (GEO) Sun-Synchronous Orbit (SSO) Geostationary Satellites (GEO) Characteristics Altitude : ~35,786 km above the equator. Period : 24 hours → same as Earth's rotation. Orbit type : Circular, directly above the equator . Appears "stationary" over one fixed point on Earth. Concepts & Terminologies Geosynchronous = orbit period matches Earth's rotation (24h). Geostationary = special type of geosynchronous orbit directly above equator → looks fixed. Continuous coverage : Can monitor the same area all the time. Applications Weather...

India remote sensing

1. Foundational Phase (Early 1970s – Early 1980s) Objective: To explore the potential of space-based observation for national development. 1972: The Space Applications Programme (SAP) was initiated by the Indian Space Research Organisation (ISRO), focusing on applying space technology for societal benefits. 1975: The Department of Space (DoS) was established, providing an institutional base for space applications, including remote sensing. 1977: India began aerial and balloon-borne experiments to study Earth resources and assess how remote sensing data could aid in agriculture, forestry, and hydrology. 1978 (June 7): Bhaskara-I launched by the Soviet Union — India's first experimental Earth Observation satellite . Payloads: TV cameras (for land and ocean surface observation) and a Microwave Radiometer. Significance: Proved that satellite-based Earth observation was feasible for India's needs. 1981 (November 20): Bhaskara-II launche...

Natural Disasters

A natural disaster is a catastrophic event caused by natural processes of the Earth that results in significant loss of life, property, and environmental resources. It occurs when a hazard (potentially damaging physical event) interacts with a vulnerable population and leads to disruption of normal life . Key terms: Hazard → A potential natural event (e.g., cyclone, earthquake). Disaster → When the hazard causes widespread damage due to vulnerability. Risk → Probability of harmful consequences from interaction of hazard and vulnerability. Vulnerability → Degree to which a community or system is exposed and unable to cope with the hazard. Resilience → Ability of a system or society to recover from the disaster impact. 👉 Example: An earthquake in an uninhabited desert is a hazard , but not a disaster unless people or infrastructure are affected. Types Natural disasters can be classified into geophysical, hydrological, meteorological, clim...

Man-Made Disasters

A man-made disaster (also called a technological disaster or anthropogenic disaster ) is a catastrophic event caused directly or indirectly by human actions , rather than natural processes. These disasters arise due to negligence, error, industrial activity, conflict, or misuse of technology , and often result in loss of life, property damage, and environmental degradation . Terminology: Anthropogenic = originating from human activity. Technological hazard = hazard caused by failure or misuse of technology or industry. 🔹 Conceptual Understanding Man-made disasters are part of the Disaster Management Cycle , which includes: Prevention – avoiding unsafe practices. Mitigation – reducing disaster impact (e.g., safety regulations). Preparedness – training and planning. Response – emergency actions after the disaster. Recovery – long-term rebuilding and policy correction. These disasters are predictable and preventable through strong...

Vineesh V, Geography

Search This Blog