“Tropical cyclones originate in the ocean and gradually weaken and terminate as soon as they approach the land. Give grounds for your explanation. (125 Words) [UPPSC 2019]
Cyclone: Definition and Causes A cyclone is a large-scale air mass that rotates around a strong center of low atmospheric pressure. It is characterized by strong winds, heavy rain, and storm surges. Cyclones can be classified into various types based on their location and formation characteristics,Read more
Cyclone: Definition and Causes
A cyclone is a large-scale air mass that rotates around a strong center of low atmospheric pressure. It is characterized by strong winds, heavy rain, and storm surges. Cyclones can be classified into various types based on their location and formation characteristics, including tropical cyclones, extratropical cyclones, and temperate cyclones.
Causes of the Origin of Temperate Cyclones
Temperate cyclones, also known as mid-latitude cyclones, occur in the mid-latitudes between 30° and 60° latitude. Their formation is influenced by several factors:
- Temperature Contrast: Temperate cyclones typically form along the polar front, where there is a significant temperature difference between cold polar air and warm tropical air. This temperature contrast creates a barometric pressure gradient which initiates the development of low-pressure systems.
- Jet Streams: The presence of jet streams, which are high-altitude, fast-flowing air currents, enhances the development of temperate cyclones. Jet streams can cause divergence at upper levels of the atmosphere, leading to the creation of low-pressure systems at the surface.
- Coriolis Effect: The Coriolis effect, resulting from Earth’s rotation, causes the cyclonic systems to rotate. This effect contributes to the counter-clockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere, driving the cyclonic circulation.
- Frontogenesis: The formation of weather fronts is crucial for temperate cyclones. A cold front (where cold air advances) meets a warm front (where warm air advances), creating a frontal zone. This interaction enhances cyclogenesis, leading to the development of cyclones.
- Upper-Level Disturbances: Disturbances in the upper atmosphere, such as shortwaves and troughs, can enhance the development of cyclones by promoting low-pressure formation and convergence at the surface.
Conclusion: Temperate cyclones originate due to the interaction of temperature contrasts, the influence of jet streams, the Coriolis effect, frontogenesis, and upper-level atmospheric disturbances. These factors combine to create dynamic and powerful weather systems in mid-latitude regions.
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1. Loss of Heat Source: Tropical cyclones derive their energy from warm ocean waters. When they move over land, they lose this primary energy source. Evaporation from the ocean, which fuels the cyclone, ceases, leading to a decrease in storm intensity. 2. Increased Friction: On land, cyclones encounRead more
1. Loss of Heat Source: Tropical cyclones derive their energy from warm ocean waters. When they move over land, they lose this primary energy source. Evaporation from the ocean, which fuels the cyclone, ceases, leading to a decrease in storm intensity.
2. Increased Friction: On land, cyclones encounter surface friction from mountains, forests, and buildings. This friction disrupts the cyclone’s circulation and reduces its wind speeds, causing the storm to weaken.
3. Reduced Moisture Supply: Cyclones require high humidity to maintain their structure. Over land, the moisture supply is limited compared to the ocean. As a result, the storm’s convective activity diminishes, leading to weakening.
4. Terrain Disruption: Landforms like mountains can disrupt the storm’s structure by breaking up the wind patterns and rainfall distribution, further contributing to the cyclone’s dissipation.
Recent Example: Cyclone Amphan (2020) weakened as it moved inland after making landfall in West Bengal, illustrating the typical weakening process of tropical cyclones over terrestrial areas.
Conclusion: Tropical cyclones weaken upon reaching land due to the loss of their heat and moisture source, increased friction, and terrain disruptions. These factors contribute to the gradual dissipation of the storm’s intensity.
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