Cyclones: Formation, Types & Effects |UPSC Notes

Cyclones are powerful and destructive weather systems characterized by intense low-pressure centers surrounded by strong winds and heavy rainfall. They form over warm ocean waters, gaining energy and strength as they move across the sea. The term “cyclone” encompasses various types of storms, including hurricanes and typhoons, which are regional names for the same phenomenon. These storms pose significant threats to coastal regions, causing severe flooding, high winds, and substantial damage to infrastructure and ecosystems.

• Cyclones form over warm ocean waters and are fueled by heat and moisture from the sea.
• The term “cyclone” includes different names for the same type of storm, such as hurricanes and typhoons.
• Cyclone impacts include high winds, heavy rainfall, and potential flooding, leading to widespread damage.
• Coastal areas are particularly vulnerable to cyclones due to their proximity to the ocean.
• Preparedness and early warning systems are crucial for mitigating the effects of a cyclone.

What is a Cyclone?

A cyclone is a large-scale air mass that rotates around a strong center of low atmospheric pressure. A cyclone is a large-scale air mass that rotates around a strong center of low atmospheric pressure. Earth’s rotation deflects moving objects through the Coriolis effect. It causes the cyclone to rotate.

The rotation of cyclone is caused by the Coriolis effect, which is the deflection of moving objects caused by the rotation of the Earth.

Cyclone typically form over warm ocean waters where the sea surface temperature is at least 26.5°C (80°F). The warm, moist air rises and cools, releasing latent heat and causing further uplift of air. This creates a cycle of rising warm air and falling cooler air, leading to the formation of a cyclone. As the cyclone gains energy, it begins to rotate and grow, driven by the heat from the ocean and the Earth’s rotation.

Formation of Cyclones

The formation of a cyclone involves a complex interplay of atmospheric and oceanic conditions. The key stages of cyclone formation include:

• Pre-existing Weather Disturbance: It often begins as a weather disturbance, such as a tropical wave, over warm ocean waters.
• Warm Ocean Waters: Sea surface temperatures of at least 26°C (79°F) provide the necessary heat and moisture to fuel the storm.
• Convection and Rising Warm Air: Warm, moist air rises from the ocean surface, creating a low-pressure area and leading to the development of thunderstorms.
• Formation of Low-Pressure System: The rising air causes the surrounding air to spiral inward, creating a cyclonic circulation pattern around the low-pressure center.
• Strengthening: As the storm system gains strength, the rotation increases, and the cyclone can develop into a more organized and intense system.

Types of Cyclones

They are classified based on their location and the specific characteristics of their formation. The main types of it include:

Tropical Cyclones

Tropical cyclones are powerful and dynamic weather systems that form over warm ocean waters, characterized by intense low-pressure centers, strong winds, and heavy rainfall. They derive their energy from the warm waters of the tropics, making them a critical focus for meteorologists and disaster management experts worldwide.

Extratropical Cyclones

Large-scale storm systems, known as extratropical cyclones, form outside the tropics, typically in temperate zones, and interact with different air masses to drive them. Extratropical cyclones derive their energy from temperature contrasts between warm and cold air. Understanding the dynamics of extratropical cyclones is essential for meteorologists and forecasters, as they play a significant role in shaping the weather patterns of temperate regions.

Subtropical Cyclones

Subtropical cyclones, forming between tropical and extratropical regions, represent a unique class of storms. These cyclones begin as tropical systems characterized by warm cores. Moving towards poleward, they undergo significant changes, eventually acquiring tropical and extratropical characteristics. 

Polar Cyclones

Polar cyclones are intense storm systems that occur in the polar regions. Low-pressure centers and cold, often unstable air masses characterize them. Polar cyclones derive their energy from the temperature contrast between cold polar air and relatively warmer ocean air. 

Major Characteristics of Cyclones

Cyclones exhibit several defining characteristics that distinguish them from other weather systems. These include:

• Cyclone’s low-pressure center, where atmospheric pressure is significantly lower than the surrounding areas.
• A well-defined eye at the center, surrounded by a ring of intense thunderstorms known as the eyewall.
• Rainbands are the spiral arrangement of cloud bands that extend outward from the eye.
• Strong winds that increase in intensity as the cyclone intensifies, often exceeding 74 miles per hour.
• Heavy rainfall can also lead to severe flooding, especially when the cyclone makes landfall.

Effects of Cyclones

It can have devastating impacts on both the natural environment and human infrastructure. Here’s an overview of the major effects of it:

Wind Damage

They produce extremely high winds that can cause severe structural damage to buildings, homes, and infrastructure. These winds can uproot trees, damage power lines, and lead to widespread power outages.

Flooding

Heavy rainfall associated with it can lead to significant flooding. This includes flash floods, and urban flooding, which can inundate homes, roads, and farmland, causing extensive damage and loss.

Storm Surge

The dangerous effect of it is storms occurring when strong winds push seawater towards the shore. It results in a rise in sea level. This can lead to severe coastal flooding, erosion, and damage to coastal habitats and structures.

Landslides

In areas with hilly or mountainous terrain, the heavy rain from cyclone can trigger landslides. These landslides can block roads, destroy homes, and pose significant risks to communities living in these areas.

Economic Impact

Cyclone can lead to substantial economic losses, including damage to homes, businesses, and agricultural lands. The cost of rebuilding and recovery can strain local and national economies, affecting livelihoods and local economies for extended periods.

Health Hazards

The aftermath of it can pose various health risks. Risks include waterborne diseases from contaminated floodwaters. Injuries from debris, and heat stress from disrupted services. A sudden increase in health needs may overwhelm public health systems.

Tropical Vs Extratropical Cyclones

Tropical Cyclones	Extratropical Cyclones
They only occur over the seas and dissipate when it reaches land.	They cover a larger area and can originate on land or at sea.
They form in warm tropical and subtropical ocean waters (5 degrees – 30 degrees latitude).	They develop in extratropical areas between 30 and 60 degrees latitude.
In tropical cyclones, the frontal system is absent.	In extra-tropical cyclones, the frontal system is present.
They get their energy from warm ocean water and the latent heat released when rising air condenses to form clouds.	They derive their energy from the difference in horizontal air mass temperatures on either side of a front.
Tropical cyclones move west to east.	Extratropical cyclones move from west to east.
Their names vary depending on where they are. They are referred to as:Cyclones (Indian Ocean)Hurricanes (Atlantic)Typhoons (Western Pacific and South China Sea)Willy-willies (Western Australia).	They are classified as Temperate Cyclones, Middle Latitude Cyclones, Frontal Cyclones, and Wave Cyclones.
In a tropical cyclone, the wind velocity is much higher and more destructive.	These cyclones don’t cause a lot of damage.However, the Braer Storm of 1993 was the most intense extratropical cyclone ever recorded over the northern Atlantic Ocean and the strongest ever recorded globally.
Generally, a tropical cyclone doesn’t last longer than seven days.	Extratropical cyclones can last for 15 to 20 days.

Cyclones UPSC Notes

1. Cyclones are intense circular storms that originate over warm tropical oceans and are characterized by low atmospheric pressure, high winds, and heavy rain. 2. They form when warm, moist air over the ocean rises and cools, leading to the development of a low-pressure system and subsequent cyclonic circulation. 3. Cyclones are classified based on their wind speeds into categories such as tropical depressions, tropical storms, and hurricanes/typhoons. 4. The Coriolis effect, caused by the Earth’s rotation, is crucial for cyclonic formation and direction, causing cyclones to rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. 5. Cyclones are most common in the tropical regions of the world, particularly in the Indian Ocean, Western Pacific Ocean, and Atlantic Ocean. 6. The intensity and impact of cyclones can be influenced by various factors, including sea surface temperatures, atmospheric conditions, and the presence of other weather systems. 7. Cyclones can lead to severe weather conditions, including strong winds, heavy rainfall, storm surges, and flooding, causing significant damage to infrastructure and ecosystems. 8. Preparedness and early warning systems are essential in mitigating the impact of cyclones, involving evacuation plans, public awareness, and improved forecasting technologies.

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