Cyclones are a dangerous natural hazard caused due to atmospheric disturbance and low pressure. Cyclones are extremely common and almost occur every year. Cyclones occur at the sea, but can sometimes reach the land and wreak havoc. Cyclones occur due to rotation of the earth (Coriolis force). Depending on the wind speed, cyclones can range from mild to extremely dangerous. While, high wind speed is a characteristic of the cyclones, the centre or the eye of the cyclone is very calm. Know more about them from this list on facts about cyclones.
What Is a Cyclone?
The cyclone is term used to describe high-speed winds rotating around a low pressure area. A satellite view of a cyclone looks like a spiral.
The pressure in the cyclone area increases as we move away from the centre and towards the circumference.
The cyclone rotates clockwise in the Northern Hemisphere and anti-clockwise in the Southern Hemisphere. This clockwise and anti-clockwise rotation of the cyclones is determined by the Coriolis Force. In fact, the same Coriolis force also contributes to the formation of polar vortices.
Cyclone Size and Wind Speed Information
The size of a cyclone can range between 100 – 2000 kilometres (62 – 1243 miles).
A depression area surrounded by high pressure winds is called a tropical cyclone when wind speeds reach 62 kph.
Cyclone is is a cause of concern when wind speeds reach 89 & 118 kmph And is called Severe Cyclone.
A cyclone with wind speeds 119 and 221 kmph is called a Very Severe Cyclone.
When cyclonic wind speeds are more than 221 kmph, it is called a Super Cyclone.
How Are Cyclones Formed
There are several separate conditions that lead to formation of cyclones.
- Cyclones require a warm core which is usually made from moist air from the sea.
- The warm core is surrounded by converging winds from different directions, which leads to condensation and formation of clouds.
- Cyclone formation is further aided by the spin of the earth and the phenomenon is known by the name of Coriolis.
Category 1: wind speeds of 74 to 95 m.p.h
Category 2: wind speeds of 96 to 110 m.p.h
Category 3: wind speeds of 111 to 129 m.p.h
Category 4: wind speeds of 130 to 156 m.p.h
Category 5: wind speeds more than 156 m.p.h
Types of Cyclones
Cyclones can be of different types depending on the size and the location where they occur. Some cyclones are known as hurricane, typhoons or tornadoes. It is usually believed that cyclones occur in a tropical region however did you know that cyclones can also occur in colder regions? Here is a look into different types of cyclones and how they are formed.
1. Tropical cyclone
As the name says, a tropical cyclone is formed over tropical or subtropical areas. These tropical cyclones are formed over the North Atlantic Ocean Eastern Pacific and western Pacific Ocean North Indian ocean and Australian region of the Indian Ocean. The cyclones are formed due to warm and moist air rising from the ocean. The area with the former make the code of the cyclone which is surrounded by converging winds in different directions.
2. Hurricanes, typhoons and tornadoes
People usually believe that Hurricane, typhoons and tornadoes are different from cyclones however they are also cyclones which are called so in the North Atlantic and Caribbean regions. North America and the regions surrounding use the term Hurricane for cyclones. Typhoon is a term used for cyclones in the Indian Ocean and South Pacific Ocean. Tornadoes on the other hand or smaller as well as more locally occurring in North America.
Mesocyclones consists of high speed thunderstorms rotating around a small area. The clouds rotating at the high speed can sometimes form a funnel like structure which when touches the ground leads to formation of a tornado.
4. Extratropical Cyclones
Extratropical cyclones are very different from the Classic cyclones. The cyclones have a cold air at the core. They are formed when cold and warm air interact with each other Or we can say that they arise because of temperature differences between two regions. The cyclones do not have very strong winds. They also usually happen in winters.
5. Polar Lows
Also known as Arctic cyclones, the polar lows are formed due to depression over the Ocean. They are also a kind of Meso cyclone That are formed over the Antarctic and the Arctic seas.
More Interesting Facts About Cyclones
- Cyclones cannot be formed near the equator because the coriolis force near the equator is 0.
- The most calm area in a cyclone is known as the eye of the cyclone and is usually in the centre of the cyclone. however the air surrounding Earth rotates at very high speed and highly destructive.
- A cyclone is given a name to wind when its speeds reach 89 kmph.
- Most cyclones occur at the sea and do not cause much harm to humans. But, they can be extremely harmful if they approach the coastal areas.
- Storm Surge is a phenomenon that happens during a cyclone when the cyclone from the sea reaches the coast. It causes water waves of huge height.
- The largest cyclone ever recorded was the typhoon “Tip”. It occured in 1979 in the Philippines. It had a diameter of 22,000 km.
- Cyclones can only occur beyond 5 degree latitudes.
- Cyclones rotate Clockwise in the Northern Hemisphere and Anti-clockwise in the Southern Hemisphere.