Table of Contents
- Tropical Cyclone
- Condition for formation of Tropical Cyclone
- Development stages of Tropical Cyclone
- Characteristics of Tropical Cyclone
- Explain the origin, development, and characteristics of a tropical cyclone. (UPPSC 2018)
- Explain the origin, distribution, and characteristics of tropical cyclones. (UPSC 1991)
- Describe the causes of origin, structure, and weather associated with tropical cyclones. ( UPPSC 2022)
Tropical Cyclone:
A tropical cyclone is a powerful storm characterized by strong winds and heavy rain that forms over warm ocean waters.
Tropical cyclone has many names. For example, a tropical cyclone is called a hurricane when it originates in the Atlantic and northeastern Pacific, a typhoon in the northwestern Pacific, a cyclone in the southern Pacific and Indian Ocean, or Willy Willy in eastern Australia.
Tropical cyclones can cause significant damage to coastal areas and are closely monitored by meteorological agencies to provide early warnings and protect affected regions.
The wind speed of a tropical cyclone may exceed 119 km per hour, and it may last from a few days to 3 weeks.
As per Ferrel's law, the wind of a tropical cyclone rotates anticlockwisewise in the northern hemisphere and clockwise in the southern hemisphere.
Condition for formation:
The key factors for the formation of a tropical cyclone include:
Warm Ocean Water:
The sea surface temperature must be at least 26 degrees Celsius or higher to provide the necessary heat and moisture for the storm's development.
Moisture in the Atmosphere:
A significant amount of moisture in the lower to mid-levels of the atmosphere is required to fuel the storm.
Low Wind:
Low wind (the change in wind speed and direction with altitude) allows the storm to remain vertically aligned and organized. High wind shear can disrupt the cyclone's structure.
A Disturbance:
A pre-existing weather disturbance ( low-pressure area), such as a cluster of thunderstorms, or an ITCZ zone, is often necessary to kickstart the formation of a cyclone.
Earth's Rotation (Coriolis Effect):
The Coriolis effect, caused by the rotation of the Earth, is crucial for the development of the cyclonic spin. It helps to initiate and maintain the rotation of the storm.
Time of Year:
Tropical cyclones typically form during specific seasons when ocean waters are warmest and atmospheric conditions are favorable. The exact timing can vary by region.
The above factors decide the intensity and development of tropical cyclones.
Meteorologists closely monitor these conditions to predict and track the formation and movement of tropical cyclones to issue warnings and protect vulnerable regions.
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| Distribution of tropical cyclone |
Stages of tropical cyclone:
There are five stages of a tropical cyclone:
- Tropical disturbances
- Tropical depression
- Tropical Storm
- Tropical cyclone development
- Dissipation
Tropical depression:
Tropical storm:
If the tropical depression continues to strengthen and its sustained winds reach or exceed 39 miles per hour (34 knots), it is upgraded to a tropical storm. At this point, the storm is given a name, and it begins to exhibit more defined spiral bands of rain and stronger winds.
Eye forms and winds start rotating around the eye.
Tropical cyclone:
When a tropical storm further intensifies and its sustained winds reach or exceed 74 miles per hour (64 knots), it is classified as Tropical Cyclone.
Tropical Cyclones are categorized on the Saffir-Simpson Hurricane Wind Scale based on their wind speeds, ranging from Category 1 (weakest) to Category 5 (strongest).
Eye forms and winds start rotating around the eye.
Tropical cyclone:
When a tropical storm further intensifies and its sustained winds reach or exceed 74 miles per hour (64 knots), it is classified as Tropical Cyclone.
Tropical Cyclones are categorized on the Saffir-Simpson Hurricane Wind Scale based on their wind speeds, ranging from Category 1 (weakest) to Category 5 (strongest).
When a full-scale tropical storm develops, it can be up to 300 kilometers in diameter.
Dissipation:
The final stage of a tropical cyclone's life cycle is dissipation, where it loses its organized structure and winds weaken significantly. This happens when the storm moves over land or into colder waters.
Characteristics of a mature tropical cyclone:
The following are the major characteristics of a Tropical Cyclone:
Central Low Pressure:
At the core of a tropical cyclone is a region of extremely low atmospheric pressure, known as the eye. This low pressure is surrounded by a larger area of lower pressure, which drives the storm's circulation.
Cyclonic Rotation:
Tropical cyclones spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Coriolis effect, a result of the Earth's rotation.
Eye:
The eye is a relatively calm, circular region at the center of the storm. Skies are often clear within the eye, and winds are light or calm. The eye is surrounded by the eyewall.
Eyewall:
The eyewall is a ring of intense thunderstorms that encircle the eye. It contains the strongest winds and heaviest rainfall in the entire storm.
Spiral Bands:
Spiral bands are curved bands of thunderstorms that spiral outward from the center of the storm. They can extend for hundreds of miles and produce heavy rain and strong winds.
Size Variability:
The size of a tropical cyclone can vary widely, with some being relatively small and compact, while others are very large, spanning hundreds of miles.
Storm Surge:
One of the most destructive aspects of tropical cyclones is the storm surge, which is a rapid rise in sea level along the coast due to the strong onshore winds and low pressure. This can cause coastal flooding.
Heavy Rainfall:
Tropical cyclones produce heavy rainfall, which can lead to flooding, landslides, and other water-related hazards.
Wind Damage:
The strong winds associated with tropical cyclones can cause extensive damage to buildings, trees, power lines, and infrastructure.
Track and Forecast Uncertainty:
Predicting the exact path and intensity of a tropical cyclone is challenging, leading to uncertainties in forecasting its behavior.
These characteristics make tropical cyclones among the most powerful and potentially destructive natural phenomena on Earth.
Meteorologists use advanced technology and models to monitor and predict their behavior, allowing for early warnings and preparations in vulnerable areas.
Question.
Explain the origin, development, and characteristics of a tropical cyclone.
(UPPSC 2018)
Answer.
Tropical cyclones are powerful storms that originate over warm ocean waters and bring about devastating impacts on coastal regions.
Let us discuss the origin, development, and key characteristics of tropical cyclones:
Origin:
Tropical cyclones form over warm ocean waters with sea surface temperatures typically exceeding 26°C. Warm ocean water provides the necessary heat and moisture to fuel the storm.
A disturbance ( low atmospheric pressure) is often needed to initiate cyclone formation.
The Coriolis effect, caused by the Earth's rotation, is essential for cyclone formation. It helps initiate and sustain the storm's rotation.
Development:
A tropical disturbance evolves into a tropical depression when it becomes more organized and develops a closed circulation pattern.
As the depression gains strength and its sustained winds reach at least 39 mph (34 knots), it is classified as a tropical storm and given a name.
These storms can continue to intensify, potentially becoming major hurricanes or super typhoons with extremely strong winds.
Characteristics:
Central Low Pressure:
Cyclones have a central area of extremely low atmospheric pressure, called the "eye," which is often calm and clear.
Cyclonic Rotation:
They spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Coriolis effect.
Eye and Eyewall:
The eye is surrounded by the eyewall, a ring of intense thunderstorms with the storm's strongest winds and heaviest rainfall.
Spiral Bands:
Curved bands of thunderstorms spiral outward from the center, bringing additional rain and wind.
Rapid Intensification:
Under favorable conditions, cyclones can undergo rapid intensification, significantly strengthening in a short time.
Size Variability:
They can vary in size, from relatively small and compact to large systems.
Storm Surge:
Cyclones bring a storm surge, a rise in sea level that can cause coastal flooding.
Heavy Rainfall:
They produce heavy rainfall, leading to flooding and landslides.
Wind Damage:
Strong winds can cause extensive damage to structures, trees, and infrastructure.
These characteristics make tropical cyclones a significant natural hazard, and meteorologists closely monitor and track them to provide early warnings and help mitigate their impacts on coastal communities.
Question.
Explain the origin, distribution, and characteristics of tropical cyclones.
(UPSC Geography 1991)
Answer.
Tropical cyclones, also known as hurricanes (Atlantic and northeastern Pacific), typhoons (northwestern Pacific), or cyclones (South Pacific and Indian Ocean), originate over warm ocean waters.
The following ways Tropical cyclones are formed:
Warm Ocean Waters:
Tropical cyclones require sea surface temperatures of at least 26°C to provide the necessary heat and moisture for their development.
Moisture and Heat:
Warm, moist air rises from the ocean's surface. As it ascends, it cools and condenses, releasing latent heat. This process fuels the cyclone, causing a low-pressure system to form.
Coriolis Effect:
The Earth's rotation induces the Coriolis effect, which causes the developing system to spin. In the Northern Hemisphere, cyclones rotate counterclockwise; in the Southern Hemisphere, they rotate clockwise.
Atmospheric Disturbance:
Often, a pre-existing weather disturbance, like a cluster of thunderstorms, is needed to trigger cyclone formation.
Distribution:
Tropical cyclones are most prevalent in specific regions of the world:
Atlantic Ocean and Eastern Pacific:
Hurricanes primarily form in the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. The eastern Pacific Ocean also experiences hurricanes.
Western Pacific:
The northwestern Pacific Ocean sees the most intense tropical cyclones, known as typhoons. These storms often impact East and Southeast Asia.
Indian Ocean:
Cyclones occur in the northern and southwestern parts of the Indian Ocean. The Bay of Bengal and the Arabian Sea are particularly prone to cyclones.
South Pacific:
Cyclones can form in the South Pacific, affecting islands in the region.
Characteristics:
Tropical cyclones exhibit several distinctive features and characteristics:
Central Low Pressure:
At their core, they have a region of extremely low atmospheric pressure, known as the eye, which is typically calm and clear.
Cyclonic Rotation:
Due to the Coriolis effect, they spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Eye and Eyewall:
The eye is surrounded by the eyewall. It has intense thunderstorms with the storm's strongest winds and heaviest rainfall.
Spiral Bands:
Curved bands of thunderstorms spiral outward from the center, bringing additional rain and wind.
Warm Core:
Tropical cyclones have warm, moist air near the surface, which is crucial for their development and strength.
Rapid Intensification:
Under favorable conditions, they can undergo rapid intensification, with a significant increase in wind speed in a short time.
Storm Surge:
Cyclones bring a storm surge, a rise in sea level that can cause coastal flooding.
Heavy Rainfall:
Tropical cyclones produce heavy rainfall, leading to flooding and landslides.
Wind Damage:
Tropical cyclone winds cause extensive damage to structures, trees, and infrastructure.
Question.
Describe the causes of origin, structure, and weather associated with tropical cyclones.
(UPPSC Mains General Studies-I/GS- 2022)
Answer.
Causes of Origin of Tropical Cyclones:
Tropical cyclones, also known as hurricanes or typhoons in different parts of the world, form over warm ocean waters in tropical and subtropical regions.
Several key factors contribute to their origin:
Warm Ocean Waters:
Tropical cyclones require sea surface temperatures of at least 26 degrees Celsius or warmer to provide the necessary heat and moisture for their formation and intensification.
Atmospheric Instability:
Warm, moist air at the surface rises and creates an area of low pressure. This rising air becomes the core of the developing cyclone.
Coriolis Effect:
The Coriolis effect, caused by the Earth's rotation, causes the developing system to spin. In the Northern Hemisphere, cyclones spin counterclockwise, while in the Southern Hemisphere, they spin clockwise.
Low Wind:
Low wind (the change in wind direction and speed with altitude) is necessary for the vertical development of a tropical cyclone. High wind shear can disrupt the cyclone formation.
Structure of a Tropical Cyclone:
A mature tropical cyclone typically has the following structure:
Eye:
At the center of the cyclone is a calm, clear, and relatively cloud-free region called the "eye." The eye is surrounded by the eyewall.
Eyewall:
The eyewall is a ring of intense thunderstorms surrounding the eye. It contains the cyclone's most severe weather, including strong winds and heavy rainfall.
Outflow:
At the upper levels of the cyclone, air flows outward from the center, creating a symmetrical outflow pattern. This outflow is important for the cyclone's sustenance and intensification.
Weather Associated with Tropical Cyclones:
Tropical cyclones are known for their destructive weather conditions, which can include:
Strong Winds:
Tropical cyclones have extremely strong winds, with sustained speeds of at least 74 miles per hour (119 kilometers per hour) for hurricanes. Category 5 hurricanes can have winds exceeding 157 miles per hour (252 kilometers per hour).
Heavy Rainfall:
Cyclones produce torrential rainfall, leading to flash floods and widespread flooding. Rainfall rates can be particularly intense within the eyewall and rainbands.
Storm Surge:
The low pressure at the center of a cyclone can cause the sea level to rise significantly near the coast, resulting in a storm surge. Storm surges can inundate coastal areas, causing extensive damage.
Large Waves and High Seas:
Tropical cyclones generate large and dangerous ocean waves, posing risks to maritime activities.
Loss of Life and Property:
Due to the combination of these severe weather elements, tropical cyclones can lead to significant loss of life and property damage when they make landfall.
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