Tropical Cyclones Formation Life Cycle Why Weaken on Land 

Tropical cyclones, also known as hurricanes or typhoons in different parts of the world, are powerful storms that form over warm ocean waters. These storms can cause extreme damage, bringing strong winds, heavy rains, and flooding when they hit land. However, one key feature of tropical cyclones is that they often weaken or dissipate once they move onto land. To understand why this happens, it is important to examine the factors that contribute to the formation of these storms and the changes they undergo when they reach terrestrial areas. What is a Tropical Cyclone? A tropical cyclone is a rotating system of clouds and thunderstorms that originates over warm tropical or subtropical oceans. These storms form when the sea surface temperature is at least 26.5°C (about 80°F), which provides the energy needed to fuel the storm. The rising warm air from the ocean surface creates low pressure at the surface, and the Earth's rotation causes the storm to spin. As the storm intensifies, it develops a distinct structure, including a well-defined center known as the "eye" of the cyclone. Why Do Tropical Cyclones Form Over Oceans? The formation of tropical cyclones is closely linked to the conditions found over the ocean. These conditions include:

Warm Ocean Water: Warm sea surface temperatures provide the heat and moisture that tropical cyclones need to grow. The warm water evaporates into the atmosphere, where it cools and condenses, releasing latent heat. This heat then fuels the cyclone, causing it to intensify. High Humidity: The moisture in the air above the warm ocean waters increases the potential for cloud formation, which is crucial for the development of the storm. Low Wind Shear: Tropical cyclones need a stable environment with low wind shear (variation in wind speed and direction at different altitudes) to form. High wind shear can disrupt the structure of the storm and prevent it from developing properly. 

Why Do Tropical Cyclones Weaken Over Land? Once a tropical cyclone moves from the ocean to land, it starts to lose its strength and eventually dissipates. 

Loss of Warm Water Supply: The most important reason tropical cyclones weaken over land is that they lose their main energy source: the warm ocean water. When a cyclone is over the ocean, the heat and moisture from the warm water continue to fuel its growth. However, once the cyclone moves onto land, there is no longer a source of warm water to provide the heat and moisture needed to sustain the storm. Without this energy, the storm begins to lose its strength. Increased Friction: When a tropical cyclone moves over land, it encounters more friction. On the ocean, the surface is smooth, which allows the storm to maintain its circular motion. But over land, the surface is rougher, with mountains, forests, buildings, and other obstacles. This increases the friction the storm experiences, causing the wind speeds to decrease and the structure of the storm to break down. Drier Air: On land, the air is typically drier than over the ocean. As a cyclone moves over the land, the dry air from the surrounding environment can enter the storm system. This drier air reduces the amount of moisture available to fuel the cyclone, which weakens the storm's intensity. Loss of Upward Motion: Tropical cyclones depend on rising warm air to maintain their structure. Over the ocean, warm air rises from the water, creating a cycle that supports the storm's development. 

On land, however, the availability of warm, moist air is limited, and the air cannot rise as efficiently. This reduces the storm's ability to sustain itself. Disruption of Storm Structure: As a tropical cyclone moves over land, its structure becomes increasingly disorganized. The storm may experience a disruption in its wind patterns, leading to a weakening of the cyclone. The pressure difference between the center and the surrounding areas decreases, reducing the cyclone's intensity. The absence of the ocean’s uniform surface also leads to a loss of symmetry in the storm’s circulation, further weakening it. Why Do Tropical Cyclones Sometimes Maintain Strength Over Land? Though tropical cyclones generally weaken after making landfall, there are some instances where they can maintain significant strength for a period of time. This can happen if the storm moves over a region that has moist conditions or if the storm moves over a large body of water like a lake or a bay, which can provide some energy. Additionally, if the terrain is relatively flat and the cyclone does not encounter too much friction, it may maintain some of its power for longer than expected. For example, tropical cyclones that hit regions with vast expanses of marshland, tropical forests, or other humid environments may retain strength for longer, as these areas can provide some moisture. Similarly, if the cyclone moves slowly or if it is a particularly powerful storm, it may not weaken as quickly. What Happens to Tropical Cyclones Once They Weaken? Once a tropical cyclone weakens, it usually turns into an area of low pressure or a remnant low. These systems can still bring rain and strong winds, but they are no longer the violent storms they were over the ocean. In some cases, the system can merge with other weather systems, causing rainfall and disturbances in the region, but the power and intensity of the original cyclone are gone. In some cases, if the remnants of a cyclone move back over the ocean, they can begin to regenerate and intensify again. However, this is a rare occurrence, and most tropical cyclones dissipate after moving onto land. Tropical cyclones are fascinating and powerful natural phenomena that rely on specific conditions to form and intensify. The ocean, with its warm waters and abundant moisture, provides the ideal environment for these storms to develop. However, once a cyclone moves onto land, it loses its main energy source, encounters increased friction, and is exposed to drier air, all of which contribute to its weakening. While tropical cyclones can cause significant destruction, especially when they make landfall, they gradually lose strength over terrestrial areas. Understanding why this happens helps meteorologists predict the behavior of storms and provide warnings to populations in affected regions. It also highlights the importance of the ocean in sustaining these intense weather systems and the vulnerability of land areas once a storm moves ashore.