The Bolivian Cyclone: A Powerful Football Legacy

A cyclone is a large air mass that rotates around a strong centre of low atmospheric pressure. In the Northern Hemisphere, cyclones rotate counterclockwise, and in the Southern Hemisphere, they rotate clockwise. Cyclones are characterised by inward-spiralling winds that rotate about a zone of low pressure. Tropical cyclones, also known as hurricanes or typhoons, are intense circular storms that originate over warm tropical oceans. They are characterised by low atmospheric pressure, heavy rain, and strong winds exceeding 119 km/h.

Cyclones are large rotating air masses

The formation of cyclones is closely tied to the heating of the ocean surface by the sun. As the air above the ocean is heated, it rises rapidly and becomes saturated with moisture, forming large thunderclouds. Cool air rushes in to fill the void, and the Earth's spinning motion, known as the Coriolis effect, causes this inflowing air to spiral upwards. This process leads to the development of a large rotating weather system, which can reach several thousand kilometres in diameter.

At the centre of a mature cyclone is a calm area known as "the eye", which is often cloudless and experiences light winds. Surrounding the eye is a wall of towering clouds, where the heaviest rains and strongest winds occur. The cyclone sustains its strength by drawing in a steady flow of warm, moist air from the ocean surface.

The terms used to describe cyclones vary depending on their location and strength. In the Atlantic and northeastern Pacific Oceans, they are referred to as "hurricanes", while in the northwestern Pacific, they are called "typhoons". In the Indian Ocean and South Pacific, they are simply known as "tropical cyclones".

They form over warm tropical oceans

Cyclones are large, rotating air masses that form over warm tropical oceans. They are characterised by inward-spiralling winds that rotate around a zone of low pressure. This zone of low pressure is known as the "eye" of the cyclone, and can extend up to 50 km, while the hurricane itself may extend outward by several hundred kilometres. Cyclones can last for several hours to more than two weeks over open waters.

Tropical cyclones, in particular, are intense circular storms that originate over warm tropical oceans. They are fuelled by a different heat mechanism than other cyclonic windstorms, making them warm core storm systems. Tropical cyclones are also known as hurricanes or typhoons, depending on where they occur. Only tropical cyclones that form over the Atlantic Ocean or eastern Pacific Ocean are called "hurricanes".

Tropical cyclones form due to significant convective activity, which is driven by the release of heat when moist air rises, resulting in the condensation of water vapour. This condensation warms the atmosphere, making the air lighter, which then continues to rise. As it does, more air moves in near the surface to take its place, creating the strong winds characteristic of these storms.

For a tropical cyclone to form, there are several key environmental conditions that must be in place. Firstly, ocean water temperatures must be sufficiently warm (at least 27°C) throughout a depth of about 46 metres. This warm ocean water powers the tropical cyclone and is the most important factor in its development. Secondly, the atmosphere must cool fast enough with height so that it is potentially unstable to moist convection. Thirdly, the air must be relatively moist near the mid-level of the troposphere (around 4,900 metres). Other conditions include a minimum distance of at least 480 kilometres from the equator, a pre-existing near-surface disturbance, and low values of vertical wind shear between the surface and the upper troposphere.

Cyclones are characterised by inward-spiralling winds

Cyclones are large air masses characterised by inward-spiralling winds that rotate around a zone of low pressure. They are defined by swift and often disruptive air circulation, with winds blowing in a large spiral around a calm centre known as the 'eye'. The Coriolis effect dictates the direction of cyclones, which rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

In meteorology, cyclones are considered low-pressure systems, with their centres (or 'eyes') containing the lowest atmospheric pressure in the region. The pressure gradient force and the Coriolis effect must be in balance for the cyclone to remain stable. Cyclones are fuelled by the heat released when moist air rises, resulting in the condensation of water vapour. They are often accompanied by thunderstorms, heavy rain, flooding, and high waves.

The formation of cyclones occurs over large bodies of warm water, where moist air rises and cools to saturation, eventually condensing into clouds and rain. Cyclones are characterised by a closed low-level atmospheric circulation, with winds flowing inwards towards the axis of rotation. This inward motion is a result of the conservation of angular momentum imparted by the Earth's rotation.

The size of cyclones varies, ranging from 100 to 2,000 km in diameter. They are largest in the northwest Pacific Ocean basin and smallest in the northeast Pacific Ocean basin. Cyclones are typically short-lived, lasting between 2 to 6 days.

There are several types of cyclones, including extratropical cyclones, subtropical cyclones, and tropical cyclones (also known as hurricanes or typhoons). Extratropical cyclones are mid-latitude cyclones that form along weather fronts, while subtropical cyclones are hybrid systems with characteristics of both tropical and extratropical cyclones. Tropical cyclones are intense circular storms that form over warm tropical oceans and are characterised by heavy rainfall and strong winds exceeding 119 km/h.

They are known by different names depending on location and strength

Cyclones are known by different names depending on their location and strength. In the North Atlantic Ocean and the eastern North Pacific, these storms are called hurricanes. In the western North Pacific, they are referred to as typhoons. In the western South Pacific and Indian Ocean, they are referred to as severe tropical cyclones, tropical cyclones, or simply cyclones. For example, the San Mateo Hurricane of 1565 got its name because it made landfall on September 22, the day after the feast of St. Matthew.

The practice of naming storms based on location is not new. Atlantic storms have been named for hundreds of years. Initially, people living in the Caribbean Islands would name storms after the saint of the day from the Roman Catholic liturgical calendar. This tradition continued until World War II, when meteorologists began using women's names, often those of wives or girlfriends, for storms instead of cumbersome designations based on latitude and longitude. Short and quickly understood, names were easier to transmit over the radio and keep straight when tracking multiple storms in a given area.

The modern system of naming storms was formalized in 1953 when the National Weather Service created an alphabetical list of female names for storms in the Atlantic basin. Male names were added to the list in 1979 when women's groups pointed out the sexism of using only female names. Today, a special committee of the World Meteorological Organization maintains lists of names for tropical cyclones. These names are short, distinctive, and relevant to their cultural and geographic areas, making them easy for people to remember.

The naming of tropical cyclones is a recent phenomenon and involves several countries in the region. For the Indian Ocean region, for example, eight countries – Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka, and Thailand – all contributed a set of names that are assigned sequentially whenever a cyclonic storm develops. The name of the cyclone that occurred last week was called Murjan, a name that came from Oman. The next in line are Mahasen, contributed by Sri Lanka, and Phailin, from Thailand.

Cyclones cause flooding and damage to infrastructure

Cyclones are large air masses that rotate around a strong centre of low atmospheric pressure. They are characterised by inward-spiralling winds that rotate about a zone of low pressure. In the Northern Hemisphere, cyclones rotate counterclockwise, and in the Southern Hemisphere, they rotate clockwise. Cyclones are formed over warm water and can last from several hours to more than two weeks over open waters.

The storm surges caused by cyclones are another significant contributor to flooding. Storm surges are elevations of the sea surface that can reach up to 6 metres (20 feet) above normal levels. These surges can move miles inland, flooding homes and cutting off escape routes. The combination of strong winds and water makes cyclones particularly hazardous for coastal areas.

The effects of cyclones can be devastating, causing loss of life, property damage, and economic impacts. The destruction caused by a cyclone depends on its intensity, size, and location. Cyclones can reshape the landscape near coastal areas, moving and reshaping sand dunes and causing extensive erosion. They can also remove forest canopy and cause wildfires. The impact on natural resources, such as coral reefs and marine life in coastal estuaries, can be significant.

Frequently asked questions