How do cyclones and hurricanes differ?

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Cyclones: Formation of hurricanes, cyclones, hurricanes and tornados

The term cyclone encompasses various types of storm that have a vertical axis of rotation as a common denominator. They usually form large cloud systems whose direction of rotation near the equator is determined by the Coriolis force. The types of cyclones differ by name, on the one hand, depending on where they originate, and on the other hand in their history, structure and destructive effects. But besides the axis of rotation, they have one thing in common: wherever they appear, they are feared.
Over the past few decades, it has been observed around the world that the frequency and strength of cyclones has increased. The reason for this is anthropogenic climate change.
Hurricanes cause great catastrophes. In addition to wind damage, there are often floods and the resulting landslides, mudslides, epidemics and famine. Hurricanes take many lives and cause enormous economic damage. Preliminary damage balance of the record hurricane Harvey, which struck the US state of Texas in August 2017: more than 150 billion USD!
Local destruction, however, also boosts the economy, as destroyed goods have to be replaced. However, this principle does not apply in poor regions. People there often suffer from the effects of storms for years.

Above all, one can distinguish between 2 different classes of cyclones: the large cloud systems, which arise exclusively over the water, and small forms which form over land. In the former, the low pressure systems fuel enormous amounts of water and latent energy from the oceans. As a rule of thumb, the higher the water temperature in the area of ​​origin, the stronger the storm!

Tropical cyclone, or cyclone

The tropical cyclone is also called cyclone. A cyclone is a low pressure system with severe thunderstorms and closed ground wind circulation around the center of the storm. They arise in the tropics, or subtropics near the equator. Due to their proximity to the equator, the direction of rotation is determined by the Coriolis force and rotate cyclonally. That is, tropical cyclones turn clockwise in the southern hemisphere and counterclockwise in the northern hemisphere. As a result, it is typical for cyclones that their cloud bands are arranged in a spiral. The wind speed of a tropical cyclone can reach over 300 km / h. However, the speed of travel of the gravure printing system is only 15-30 km / h. This is what makes them so extremely destructive. Tropical cyclones often bring huge amounts of water with them. They are typical of the Indian Ocean in the area of ​​the island world around Madagascar. This also includes the volcanic island of La Réunion. They are just as feared on the East African coast as they are in the southern Pacific around Australia.

Typhoons in Asia

A tropical cyclone in the Asian region is the typhoon. If you look closely, these cyclones are at home in East and Southeast Asia as well as in the northwestern part of the Pacific, west of the international date line and north of the equator. A typhoon is formed by a powerful low pressure area and brings with it huge amounts of water that lead to flooding.

Hurricanes and Medicane

Hurricanes occur in the North Atlantic and North Pacific east of 180 ° longitude and in the South Pacific east of 160 ° east, east of the international date line, in the Caribbean Sea and in the Gulf of Mexico. The most devastating hurricanes have raged there in the last few decades, and due to their location, they also aroused the greatest media interest.
A storm low turns into a hurricane when a maximum mean wind force of over 64 knots (118 km / h) is reached. A special form of hurricanes has been observed over the Mediterranean: the so-called Medicane, storms that are similar to tropical cyclones. The term Medicane is a combination of the English expressions Mediterranean Sea and Hurricane.

Hurricanes over Europe

Whirling storms in moderate latitudes are called hurricanes. As soon as winds with speeds of more than 117 km / h occur in a low pressure system, one speaks of a hurricane. They arise in Central Europe mainly in autumn and winter, when the temperature differences between the polar region and the south are particularly large. Hurricanes are the strongest storms in extra-tropical wind systems and have great destructive potential. They are particularly dangerous for seafarers and coastal residents, as they romp around here unchecked.

Tornadoes and waterspouts

Tornadoes are also hurricanes, but they differ from the previous ones in many ways. They can form over land and are very small compared to hurricanes and cyclones. They are localized phenomena, the origin of which has not been clarified in detail. Tornadoes are also called large turbines and are by definition small-scale air eddies that are created by & xnbsp; moisture convection & xnbsp; and wind shear in the earth's atmosphere. As a basic requirement, warm, humid air must rise very high. If a tornado forms over water, it is called a waterspout. A tornado rotates very quickly around its vertical axis. Inside there is a strong negative pressure, which creates a suction effect upwards. The distinctive trunk is formed, which is known from many films. The speed of rotation of a tornado can be up to 300 km / h. A tornado moves over the ground at speeds of 50 to 100 km / h and lasts an average of 10 minutes.

Image source: Alexander Gerst / ESA / NASA

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