CYCLONE MOCHA - GEOGRAPHY
News: Cyclone
Mocha building over Bay of Bengal, says IMD: How are cyclones formed and named?
What's in the news?
● The
Indian Meteorological Department (IMD) has said that a cyclonic or low-pressure
area is developing in the Bay of Bengal and can lead to high rainfall in the
next few days in the region, from May 8 to May 12.
● It
also said that the weather system was likely to form a depression over the
southeast Bay of Bengal around May 9, and then intensify into a cyclonic storm.
Key takeaways:
● The
cyclone Mocha (Mokha) was named by Yemen
after the Red Sea port city, which is known to have introduced coffee to the
world over 500 years ago.
Cyclone:
● A
cyclone is a low-pressure system that forms over warm waters.
Favourable Conditions for the Formation of Tropical
Cyclone:
● A
large area of water surface with a temperature
above 27° C
● The
Coriolis force is strong enough to
form a cyclonic vortex.
● Variations in the
vertical wind speed are minor.
● A
weak low-pressure area or low-level
cyclonic circulation already exists.
● Above
the sea level system, there should be a higher
divergence.
Developmental Stages of Tropical Cyclone:
Tropical
cyclones can be classified into three stages throughout their development.
1. Formation and Initial Development Stage:
● The
transport of water vapor and heat from the warm ocean to the overlying air,
largely through evaporation from the sea surface, is crucial to the creation
and early development of a cyclonic storm.
● Convection
with condensation of rising air above the ocean surface stimulates the creation
of huge vertical cumulus clouds.
2. Mature Stage:
● The
air rises in powerful thunderstorms as a tropical storm intensifies, and it
tends to spread out horizontally at the tropopause level.
● When
air spreads out, a positive pressure is created at high elevations, speeding up
the downward migration of air due to convection.
● When
subsidence is induced, the air warms up due to compression, resulting in a warm
‘Eye’ (low-pressure center).
● A
mature tropical cyclone in the Indian Ocean has a concentric pattern of highly
turbulent large cumulus thundercloud bands as its principal physical feature.
3. Modification and Decay:
● As
soon as its source of warm moist air begins to ebb or is abruptly cut off, a
tropical cyclone begins to weaken in terms of core low pressure, internal
warmth, and extremely fast speeds.
● This
occurs after it reaches land or passes across chilly water.
Local Names:
● North
Atlantic (including Caribbean and Gulf of Mexico): Hurricanes
● Eastern
and Central North Pacific: Hurricanes
● Western
Northern Pacific: Typhoons
● Arabian
Sea/Northern Indian Ocean: Tropical Cyclones
● South
Indian Ocean: Tropical Cyclones/Willy-Willy for southwest Australia
● Coral
Sea/South Pacific: Tropical Cyclone.
Impacts of tropical cyclones:
● Tropical
cyclones are one of the biggest threats
to life and property even in the formative stages of their development.
● They
include a number of different hazards that can individually cause significant
impacts on life and property, such as storm surge, flooding, extreme winds,
tornadoes and lighting.
● Combined,
these hazards interact with one another and substantially increase the
potential for loss of life and material damage.
Naming of cyclones:
Regional Specialised Meteorological Centres (RSMCs):
● Cyclones
that form in every ocean basin across the world are named by the Regional
Specialised Meteorological Centres (RSMCs) and Tropical Cyclone Warning Centres (TCWCs).
● There
are six RSMCs in the world,
including the India Meteorological Department (IMD), and five TCWCs.
IMD as RSMC:
● As
an RSMC, the IMD names the cyclones developing over the north Indian Ocean,
including the Bay of Bengal and the Arabian Sea, after following a standard
procedure.
● The
IMD is also mandated to issue advisories to 12 other countries in the region on
the development of cyclones and storms.
Panel on Tropical Cyclones:
● In
2000, a group of nations called WMO/ESCAP (World Meteorological
Organisation/United Nations Economic and Social Commission for Asia and the
Pacific), which comprised Bangladesh, India, the Maldives, Myanmar, Oman,
Pakistan, Sri Lanka and Thailand, decided to start naming cyclones in the
region.
● After
each country sent in suggestions, the WMO/ESCAP
Panel on Tropical Cyclones (PTC) finalised the list.