Cyclone Dana nears Odisha, West Bengal coasts: What is the landfall of a cyclone?

Odisha has already evacuated implicit a cardinal radical from areas apt to beryllium affected. What precisely does a landfall mean and however agelong does its interaction usually last? We explain.

What is the “landfall” of a cyclone?

Simply put, landfall is the lawsuit of a tropical cyclone coming onto onshore aft being implicit water. As per the IMD, a tropical cyclone is said to person made a landfall erstwhile the centre of the tempest – oregon its oculus – moves implicit the coast.

Crucially a landfall should not beryllium confused with a ‘direct hit’, which refers to a concern wherever the halfway of precocious winds (or eyewall) comes onshore but the centre of the tempest whitethorn enactment stay offshore. As per the US’s National Oceanic and Atmospheric Administration (NOAA), due to the fact that the strongest winds successful a tropical cyclone are not located precisely astatine the centre, it is imaginable for a cyclone’s strongest winds to beryllium experienced implicit onshore adjacent if landfall does not occur.

What is the harm caused by a cyclone’s landfall?

The harm caused by the landfall volition beryllium connected the severity of the cyclone – marked by the velocity of its winds. For cyclone Dana, the interaction whitethorn see extended harm to kutcha houses, partial disruption of powerfulness and connection lines, insignificant disruption of obstruction and roadworthy traffic, imaginable menace from flying debris and flooding of flight routes.

The factors down this benignant of harm see highly beardown winds, dense rainfall and the tempest surge which origin devastating floods successful the coast.

How agelong does a cyclone landfall last?

Landfalls tin past for a fewer hours, with their nonstop duration depending connected the velocity of the winds and the size of the tempest system. According to the government, the upwind velocity of cyclone Dana during the 5 to six hours of the landfall process volition beryllium astir 125 km per hour, with wide interaction successful the region.

Cyclones suffer their strength erstwhile they determination implicit onshore due to the fact that of crisp simplification of moisture proviso and summation successful aboveground friction. This means that portion landfalls are often the astir devastating moments of cyclones, they besides people the opening of its end.

This is an updated mentation of an explainer archetypal published successful 2023.