With Cyclone Dana looming large to the Odisha coast, the state authorities have launched a massive evacuation campaign for its people. Since cyclone is likely to hit Bhitarkanika or Dhamra, about 10,60,336 have been shifted to safer places.
The Evacuation Effort
The Odisha government has included more than 3000 bad areas in about 14 districts, mostly in the coastal area. Senior superintendents and disaster management teams are closely supervising the on-going evacuation process.
Cyclone Dana's Impact
Forecast on cyclone Dana indicated that it is likely to hit the area with the wind speed of 100-120 kmph and intense precipitation. The government has also put up emergency control rooms and placed several rescue teams to attend to the situation.
Relief and Rescue Operations
To support the event there are 288 search and rescue teams along with the state coordination. The National Disaster Response Force (NDRF) has also been sounded, and 56 teams have been deployed in 5 states, of which Odisha also forms part. Necessary provisions and cooked foods, besides other arrangements are being made by Government in cyclone shelters.
Environmental Concerns
A storm surge of about 1 meter high is anticipated to affect this cyclone, hence flooding areas which are relatively flat along the coastal line. Wildlife officials are also awake, with emergent groups prepared to retrieve crocodiles and snakes that are likely to be washed away by the floods.
The Odisha government’s has shown efficient and effective preparedness and response to Cyclone Dana. The displacement of 10,60,336 people is an indication of the state government’s effort to protect its people. Being proactively prepared together with active government Agencies, rescue teams, and the community, Odisha is readying itself to emerge stronger in the face of the storm.
Cyclones are severe and most times disastrous natural vices with features of tremendous wind speeds, torrential rains and floods. These can be destructive to life and property and thus their formation, types and effects must be well understood.
What is a Cyclone?
A cyclone in the large-scale lower pressure control air mass going round the main control point of low pressure. Certainly the rotation is seen to be in the anticlockwise fashion in the Northern hemisphere and in the clockwise fashion in the southern half of the globe. Tropical cyclones are of two categories depending on the location and strength and they are essential in climatic system on earth.
Types of Cyclones
Cyclones are broadly categorized into two main types: Of these the two most common types are tropical cyclones and extra-tropical cyclones.
1. Tropical Cyclones:
- Definition: Tropical cyclones are all circular storms that form over warm tropical or subtropical sea.
- Classification: The Types of disturbances are distinguished in accordance with their wind velocity and activity referring to them as tropical depressions, tropical storms, hurricanes (North Atlantic), typhoons (Western Pacific), or cyclones (Indian Ocean and South Pacific).
- Formation Regions: These cyclones mostly develop between 5 and 30 degrees latitude in each hemisphere as Sea Surface Temperature of not less than 26.5°C (79.7°F).
- Structure: The center of the tropical cyclone is characterized by an eye, while the cyclone’s strongest winds and precipitation occur in an eyewall that encircles the eye. Spiral rainbands are line features that are observed to radiate from the centre of the spiral.
2. Extra-tropical Cyclones:
- Definition: Frontal cyclones otherwise referred to as mid-latitude or extra-tropical cyclones, develop outside the tropical areas. They are related to weather fronts and organized in a different way and come into being as tropical cyclones.
- Classification: These cyclones are not categorized but just classified based on strength as depressions, storms, and polar lows.
- Formation Regions: Extra-tropical cyclones occur in latitudes 30 – 60 degree in the two hemispheres and mostly develop where there are frontal convergence of warm and cold air masses.
- Structure: A defining feature of the extra-tropical cyclone is the lack of an eye. It rises with a multifaceted structure that includes occluded front, cold front, and warm front.
How Cyclones are formed
Cyclones are the products of interaction between atmospheric and oceanic processes that have undergone severe transformation. Below is a detailed elaboration of the formation processes of both tropical and extra-tropical cyclones.
1. Formation of Tropical Cyclones:
- Warm Ocean Waters: Essentials of development of tropical cyclones involve warm sea surface, which can be either at least 26.5°C or 79.7°F. For the cyclone to be generated there is need to have heat and moisture from these waters.
- Low-Pressure Area: A low pressure system is a region of the earth’s surface over the sea where warm and wet air is evaporated as it encounters elevated temperatures. This leads to condensation which loses heat and makes the pressure even lower.
- Convergence and Rotation: A combination of the Coriolis Effect results from the rotation of the Earth moving the rising air spiralling a cyclonic circulation.
- Development of the Eye: When cyclone strengthens, there is formation of rotation and upward movement then the focused eye near the central point, the radiating wall that encompasses strong wind and precipitation known as the eyewall.
- Outflow at Upper Levels: Over the higher terrain, air is again moved outwards thus preserving the low pressure in the center of the valley at the surface layer. This outflow is required in order to support the cyclone.
2. Formation of Extra-tropical Cyclones:
- Temperature Contrasts: Extra-tropical cyclones originate at frontal zones on middle and high latitudes, where there is clear separation between warm and cold air. These temperature differences play the role of energy in cyclogenesis.
- Cyclogenesis: The first step in the formation of extra-tropical cyclone is cyclogenesis which is instigated by a special condition within the atmosphere that results in the warm air rising while cold air falls.
- Mature Cyclone: As the cyclone strengthens, we see that the warm front has a well defined path as does the cold front. The low-pressure centre continues to extend and thus the cyclone becomes deeper and there are gusty winds and rain.
- Occlusion: At a later period, the cold front over takes the warm front and that is referred to as the occluded front. As the temperature contrast decreases the cyclone also starts losing its strength.
Tropical or extra-tropical cyclones represent violent meteorological events generated through a complex of the atmospheric and oceanic processes. Studying the structure and the nature of these phenomena enables one to see how they are likely to develop and, therefore, how to asses them. As for cyclones, it means that corresponding scientifically based preparations and precautions for such a majestic but dangerous power of a hurricane-like tornado can be made.
Naming of Cyclones
Cyclone naming mechanism is international, well planned and structured with the help of many weather organizations in the world. The primary reason for naming of cyclones is to distinguish between two different cyclonic systems when there are one or more cyclones are about to occur at the same time.
History of Cyclone Naming
The process of giving cyclone a name has been done from early 1900. At the beginning of cyclone naming it was conducted according to the places where the cyclone occurred or events. Cyclones were named after females during World War II and the practice was extended until late 70s when the cyclone names both male and female were used.
Naming Authorities
Formerly, distinct parts of the world have specialized organizations which are in charge of giving names to cyclones. All these organizations work under the standards of World Meteorological Organization –WMO. The primary naming authorities include:
- North Atlantic and Eastern North Pacific: NHC as its name depicts is the National Hurricane Center of the United States and the other is Central Pacific Hurricane Center (CPHC).
- Western North Pacific: The two sources used for this study were the Japan Meteorological Agency (JMA) and the Typhoon Committee.
- North Indian Ocean: India Meteorological Department (IMD) based on the physical parameters of mean sea level pressure and sea surface temperatures.
- South-West Indian Ocean: Regional specialized meteorological center, La Réunion island.
- Australian Region: Australia’s Bureau of Meteorology (BoM).
- South Pacific: Fiji Meteorological Service and New Zealand’s Tropical Cyclone Warning Centre.
Process of Naming
- Pre-Approved Lists: Tropical cyclone names are from list prepared exclusively by the regional meteorological organization. Such lists normally exist several years before and include names that are relevant to the culture and language of the regions the companies operate in.
- Rotating and Retirement: Actually, the lists of cyclone names are circulated annually, though the common names are repeated after few years. But if cyclone is very destructive and caused many losses, its name is taken off the list due to confusion likely to be caused by such name in future, as well as to pay respect to the affected people. The retired name is subsequently replaced by a new name.
- Naming Criteria: Cyclones are named once they’re stronger, or once they have become a ‘tropical storm’, say their wind speeds are above a certain level (39 mph or 63 km/h for a cyclone in the Atlantic region). It is the responsibility of the specific Regional Specialised Meteorological Centre (RSMC) or the Tropical Cyclone Warning Centre (TCWC), which is following the storm.
Regional Variations
- Atlantic and Eastern North Pacific: In these regions it appears that names are given alphabetically according to files containing male and female names in turn. The names which are rubbed on the cylinder starts with 'A' each year and goes up to 'Z'. For instance, the names that were on the list for the Atlantic in 2021 were Ana, Bill, Claudette as well as Danny.
- Western North Pacific: This is the system of naming in this part of the world where member countries to the Typhoon Committee submit names. The names are those of the cultures and languages of some of the member countries. For instance, such names as Hagibis which was provided by the Philippines or Hato provided by the Japanese are used.
- North Indian Ocean: Current cyclone names in the North Indian Ocean are provided by the countries within the basin of the cyclone namely India, Bangladesh, Myanmar and Thailand. The names are taken in numeration from the list mentioned regardless of the country from which this or that name comes from. For example, there are some names as Nivar in India or Yaas in Oman.
Importance of Naming
Naming cyclones serves several important purposes:
- Effective Communication: Thus, using names contribute to the efficient communication between the media, other groups and the general public in relation to specific cyclones and dissemination of information regarding the cyclone and precautions to be taken.
- Clarity: Since there could be two or more cyclones at the same time, the names make sure that the advisories and the warnings given out are clearly understood.
- Preparedness: Named cyclone is more effective since it makes the affected people to be more prepared to do certain measures such as evacuation.
It is important and orderly procedure to designate cyclones and it helps to provide efficient communication on the disaster. Therefore, with adherence to a systematic approach and jurisdiction-specific linguistic and cultural peculiarities, meteorological organizations make certain that every cyclone is qualified clearly and its risks easily recognizable. Thus, this process not only improves public awareness and risk reduction of humanity to such powerful natural disasters.