Tropical Cyclones are violent storms that originate over oceans in tr...
Formation of Tropical Cyclones
Tropical cyclones, also known as hurricanes or typhoons, are violent storms that originate over oceans in tropical areas. They are characterized by strong winds, heavy rainfall, and low atmospheric pressure. Several conditions are necessary for the formation of tropical cyclones.
1. Sea Surface Temperature Higher than 27°C
One of the key conditions favorable for the formation of tropical cyclones is a sea surface temperature higher than 27°C (81°F). Warm ocean water serves as the primary source of energy for tropical cyclones. When the ocean surface is warm, it provides the necessary heat and moisture for the storm to intensify. As the warm air rises, it creates a low-pressure area, and the surrounding air rushes in to fill the void, creating strong winds. Therefore, a high sea surface temperature is essential for the formation and intensification of tropical cyclones.
2. Absence of Coriolis Force
The Coriolis force is caused by the Earth's rotation and is responsible for the deflection of air currents in the atmosphere. It plays a crucial role in the formation of tropical cyclones by initiating the rotation of the storm. In the Northern Hemisphere, the Coriolis force deflects air to the right, while in the Southern Hemisphere, it deflects air to the left. Therefore, the absence of the Coriolis force would prevent the cyclonic rotation necessary for the formation of tropical cyclones.
3. High Variations in the Vertical Wind Speed
High variations in the vertical wind speed are also favorable for the formation of tropical cyclones. These variations create an upward motion of air, known as convection, which is crucial for the development of thunderstorms and the subsequent formation of tropical cyclones. The upward motion of air allows for the release of latent heat, further fueling the storm and contributing to its intensification.
Conclusion
Out of the provided conditions, only condition 1 (sea surface temperature higher than 27°C) is favorable for the formation of tropical cyclones. Condition 2 (absence of Coriolis force) is incorrect since the Coriolis force is essential for the cyclonic rotation of the storm. Condition 3 (high variations in the vertical wind speed) is also incorrect as it does not directly contribute to the formation of tropical cyclones. Therefore, the correct answer is option 'B' - 1 only.
Tropical Cyclones are violent storms that originate over oceans in tr...
- Tropical cyclones originate and intensify over warm tropical oceans. The conditions favourable for the formation and intensification of tropical storms are:
- Large sea surface with a temperature higher than 27° C; Hence option 1 is correct.
- Presence of the Coriolis force Hence option 2 is not correct.
- Small variations in the vertical wind speed; Hence option 3 is not correct.
- A pre-existing weak low-pressure area or low-level-cyclonic circulation.
- Upper divergence above the sea level system.
The cyclones, which cross 20°N latitude generally, recurve and they are more destructive (cyclones do not form near the equator due to the absence of Coriolis force). A mature tropical cyclone is characterized by the strong spirally circulating wind around the centre, called the eye. The diameter of the circulating system can vary between 150 and 250 km. The eye is a region of calm with subsiding air. Around the eye is the eyewall, where there is a strong spiralling ascent of air to a greater height reaching the tropopause. The wind reaches maximum velocity in this region, reaching as high as 250 km per hour. Torrential rain occurs here. From the eyewall, rain bands may radiate and trains of cumulus and cumulonimbus clouds may drift into the outer region. The diameter of the storm over the Bay of Bengal, the Arabian Sea and Indian ocean is between 600 and 1200 km. The system moves slowly about 300 - 500 km per day. The cyclone creates storm surges and they inundate the coastal low lands. The storm peters out on the land.
To make sure you are not studying endlessly, EduRev has designed UPSC study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in UPSC.