Hurricane Ida

In News 

• Recently, Hurricane Ida struck the Louisiana coast in the USA.
  • It is regarded as an extremely dangerous Category 4 storm.

What are Hurricanes?

• They are enormous storms that come with a rotating wind speed of 74 miles per hour. 
  • The rotating wind swirls across the warm water of the tropics and comes with terrifying force.
• They are one of the most violent storms on earth and formed over the warm ocean waters near the equator.
• The term “hurricane” is usually used for the large storms that are formed over the Atlantic Ocean or the eastern Pacific Ocean.
• The first hurricane every year gets a name starting with the letter A, second with B, and so on.
• Depending on where they occur, hurricanes may be called typhoons or cyclones. 
• Naming:

• Each year, tropical storms are named in alphabetical order. The names come from a list of names for that year. There are six lists of names. Lists are reused every six years.

• They are given many names in different regions of the world:
  • Typhoons: tropical cyclones are known as Typhoons in the China Sea and the Pacific Ocean.
  • Hurricanes: In the West Indian islands in the Caribbean Sea and the Atlantic Ocean.
  • Tornados: In the Guinea lands of West Africa and southern USA.
  • Willy-willies: In north-western Australia and
  • Tropical Cyclones: In the Indian Ocean Region.

• Mechanism of its formation: 
  • Low-Pressure Creation: When the warm, moist air rises upward from the surface of the ocean, it creates an area of low air pressure below. 
    • When this happens, the air from the surrounding areas rushes to fill this place, eventually rising when it becomes warm and moist too.
  • An eye forms in the centre:  It is the calmest part of the cyclone. Before the wind reaches the centre it gets warmed up and rises upward and when the warm air rises and cools off, the moisture forms clouds. This system of clouds and winds continues to grow and spin.
  • This disturbance is fuelled by the ocean’s heat and the water that evaporates from its surface and such storm systems rotate faster and faster.
  • Storms that form towards the north of the equator rotate counterclockwise, while those that form to the south spin clockwise because of the rotation of the Earth.
  • A hurricane can last for more than 14 days.

• Structure:
  • Eye- Hurricane winds blow in a counterclockwise spiral around the calm, roughly circular centre called the eye. The eye is the warmest part of the storm and it is relatively calm, clear and there is little or no rain in this region.
  • Eyeball- Surrounding the eye is the eyewall, a wall of thunderclouds. The eyewall has the most rain and the strongest winds of the storm, gusting up to 360 km/h in severe storms.
  • The smaller the eye, the stronger the winds. The winds spiral in a counterclockwise direction into the storm’s low-pressure centre.
  • Spiral Rainbands– Long bands of rain clouds appear to spiral inward to the eyewall — these are called spiral rainbands. They contain thunderstorms and sometimes tornadoes

                                                       Image Courtesy: enchanted learning 

Source: TH