Understanding Tropical Cyclone Movement
Tropical Cyclones Formation and Movement
Tropical cyclones form over warm ocean waters where the sea surface temperature is around 26º C or higher. These conditions provide the necessary heat and moisture for their growth. Once formed, their movement is dictated by surrounding wind patterns, akin to a leaf carried by a river.
Global Wind Patterns
- The trade winds, part of the global Hadley circulation, influence cyclones' paths. These winds blow from east to west between roughly 5º and 20º north and south of the equator.
- The Hadley circulation is driven by the earth’s uneven heating, with warm air rising near the equator and cooling as it moves towards the poles before sinking around the 30º latitude.
- The Coriolis effect causes the returning air to deflect westward, creating the easterly trade winds. This pattern pushes cyclones westward across oceans, influencing their paths significantly.
Cyclone Paths in Different Oceans
- In the Bay of Bengal, cyclones tend to move towards India’s east coast.
- In the Atlantic Ocean, they move from Africa towards the Caribbean and the Americas.
- In the Pacific Ocean, they often head towards Asia and Australia.
Influence of Monsoons on Cyclone Movement in the Arabian Sea
In the Arabian Sea, cyclones often move towards India due to the monsoons, despite the general westward push of the trade winds.
- From June to September, the southwest monsoon causes winds to blow from the southwest to the northeast, directing cyclones towards India’s western coast, affecting Gujarat, Maharashtra, and sometimes Kerala.
- During winter and early spring, the northeast monsoon reverses the surface flow, directing winds from the Indian subcontinent towards the equator and Africa. Cyclones during this period may drift westwards.
Additional Influences on Cyclone Paths
- Other atmospheric systems, such as mid-latitude westerlies, can also alter a cyclone's course, sometimes steering it harmlessly into open water.
- The strength and direction of the steering winds, like during Cyclone Michaung in December 2023, can cause cyclones to linger offshore before landfall if the winds are weak.
Ultimately, the interaction between the trade winds, monsoons, and additional atmospheric conditions largely determines the path and impact of tropical cyclones in various regions.