Recently, Vardah , a tropical cyclone had hit India causing asset destruction in the coastal areas of Andhra Pradesh and Tamil Nadu.
Here is a precise dose of awareness about the tropical cyclones for you to understand the various aspects related to it.
What are tropical cyclones?
These are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing large scale destruction caused by violent winds, storm surges ,and very heavy rainfall.
What are the preconditions for cyclone formation?
- Sea Surface Temperature: 27 degree C.
- Presence of Coriolis force(an inertial force which act on the objects in motion w.r.t rotating reference frame).
- Small variations in vertical wind speed.
- Pre-existing low-pressure area or low-level cyclonic circulation.
- Upper divergence above the sea level system.
How does a tropical cyclone look like?
- A region of calm with subsiding air–>around the eye is eye wall, where there is strong spiraling ascent of air to greater height reaching the troposphere.
- From the eye wall, rain bands may radiate and trains of cumulus and cumulonimbus clouds may drift into the region.
- Energy to the cyclone is provided by continuous process of evaporation . With continuous supply of moisture from the seas, it is further intensified.
- When the supply of mositure from the seas is cut off, the cyclone falls. This is called landfall of a cyclone.
What is the impact of the cyclones?
- Widespread destruction in terms of life and assets.
- Ecological imbalances and a huge loss to the environment.
- Wide deviation of life from normalcy.
How are cyclones named?
In 2004, an international panel on tropical cyclones decided that countries from the region would each put in names, which would be assigned to storms in the Bay of Bengal and Arabian Sea.
- Eight countries — India, Pakistan, Bangladesh, Maldives, Myanmar, Oman, Sri Lanka, and Thailand – participated and came up with a list of 64 names.
- In the event of a storm, the Regional Specialized Meteorological Centre, New Delhi, selects a name from the list.
Some guidelines for naming are:
- A name, for instance : short and readily understood
- Neutral–> not culturally sensitive and not convey some unintended and potentially inflammatory meaning
This is the system in the region given above.
The cyclones are known by different names in different places:
- Hurricanes:North America
- Willy Willies: Australia
Which regions of the world are vulnerable to tropical cyclones?
Why India’s east coast is more vulnerable than the West coast?
- Bay of Bengal
- Cyclones that form over the Bay of Bengal are either those develop insitu over southeast Bay of Bengal and adjoining Andaman Sea or remnants of typhoons over northwest Pacific and move across south China sea to Indian Seas.
- As the frequency of typhoons over northwest Pacific is quite high (about 35% of the global annual average), the Bay of Bengal also gets its increased quota.
- Arabian sea:
- The cyclones over the Arabian Sea either originate insitu over southeast Arabian Sea (which includes Lakshadweep area also) or remnants of cyclones from the Bay of Bengal that move across south peninsula.
- As the majority of Cyclones over the Bay of Bengal weaken over land after landfall, the frequency of migration into Arabian Sea is low.
- In addition to all the above the Arabian Sea is relatively colder than Bay of Bengal and hence inhibits the formation and intensification of the system.
How can the impact of the cyclones be mitigated?
- Early Warning Systems.
- Cyclone shelters.
- Cyclone resistant infrastructure.
- Displacement and Rehabilitation of people living near the coasts to faraway places.
- Planting deep and strong rooted trees on the coast to impede the strength of the cyclone.
- Building embankments along the coast.