Why do cyclone happen

When the winds reach between 25 and 38 mph, the storm is called a tropical depression. When the wind speeds reach 39 mph, the tropical depression becomes a tropical storm. This is also when the storm gets a name. The winds blow faster and begin twisting and turning around the eye, or calm center, of the storm. Wind direction is counterclockwise west to east in the northern hemisphere and clockwise east to west in the southern hemisphere. This phenomenon is known as the Coriolis effect.

When the wind speeds reach 74 mph, the storm is officially a hurricane. The storm is at least 50, feet high and around miles across. The eye is around 5 to 30 miles wide. A cumulonimbus cloud. A tropical cyclone has so many of these, they form huge, circular bands. Air from surrounding areas with higher air pressure pushes in to the low pressure area. Then that "new" air becomes warm and moist and rises, too.

As the warm air continues to rise, the surrounding air swirls in to take its place. As the warmed, moist air rises and cools off, the water in the air forms clouds. The whole system of clouds and wind spins and grows, fed by the ocean's heat and water evaporating from the surface. Storms that form north of the equator spin counterclockwise. Storms south of the equator spin clockwise. This difference is because of Earth's rotation on its axis. The strongest wind gust recorded at Port Hedland during a cyclone is kph during Joan in In general, cyclones near Australia have more erratic paths than cyclones in other parts of the world.

The Bureau of Meteorology lists cyclone severity and potential damage they may cause as follows:. Climate change would suggest warmer sea temperatures in some parts of the world, and warm sea temperatures create ideal conditions for cyclones to form. The weather bureau says it is difficult to sort out natural trends, such as those caused by El Nino events, from the effects of global warming.

Some studies cited by the bureau have predicted more severe storms by the middle of the 21st century, and storms that extend further towards the north and south poles. One study predicts more long-lived cyclones off the eastern coast of Australia and fewer long-lived cyclones off WA. Hurricanes and typhoons are regional names for severe tropical cyclones, or storms with sustained winds of more than kilometres per hour. The word hurricane is used for storms in the north Atlantic, the north-east Pacific, and the south-east Pacific.

Typhoons are found in the north-west of the Pacific Ocean. Storm systems turn anti-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Tornados are born out of thunderstorms and are tiny by comparison — generally only about metres across.

There is a committee at the World Meteorological Organisation in Geneva that decides the names many years in advance. They have a list of names for each region in the world that is responsible for identifying and classifying a tropical cyclone. Importantly they never use the names of previous cyclones again in case some members of the public think Cyclone Tracy or Hurricane Katrina, for example, have come back. That is impossible, of course, but some may fear a cyclone with the same name might have the same impact.

We acknowledge Aboriginal and Torres Strait Islander peoples as the First Australians and Traditional Custodians of the lands where we live, learn, and work. Damage to some crops, trees and caravans. Significant damage to signs, trees and caravans. Heavy damage to some crops. Some caravans destroyed. When there are definite indications that a tropical cyclone is approaching land, watches and warnings along coastal regions are raised, which aim to give information to the local authorities of places likely to be in the tropical cyclone's path, so that they can make preparations to protect public safety.

Specially designed shelters in which people can ride out the worst of the weather may have been built in advance. Coastal regions immediately in a tropical cyclone's path are particularly dangerous and people are usually advised to move away from these. In the USA, this can involve the mass evacuation of a million or more people.

Warnings are broadcast on TV and radio. NOAA Weather radio is available on a variety of frequencies and gives up-to-date information and advice. There is also a lot of information on a variety of web sites, the most authoritative being those maintained by NOAA and the National Hurricane Center. Tropical cyclones warnings and guidance. Hurricanes are tropical features and require sea temperatures much higher than those around the UK, even in the summer.

Hence, hurricanes cannot form at our latitudes. However, we are sometimes affected by deep depressions that were originally tropical cyclones which have moved to higher latitudes, such as ex-Hurricane Ophelia in Intense mid-latitude depressions can produce near surface winds of hurricane strength, even those which do not originate from a tropical cyclone. The most widely publicised such depression occurred on 16 October , known as The Great Storm.

Some wind gusts were over m. On 13 February a deep depression passed just to the north of Scotland producing a gust of m. The reason that The Great Storm of October gained such publicity was that it occurred in a densely populated area causing loss of life and enormous damage to trees. The Great Storm of The impact of climate change - specifically global warming caused by the burning of fossil fuels - on tropical cyclone activity is the subject of ongoing debate and research in the scientific community.

Recent catastrophic events, such as Typhoon Haiyan and Hurricanes Harvey, Irma and Maria, have given the debate a higher profile. While some evidence has been presented in order to indicate a recent upturn in tropical cyclone activity in some parts of the world, others have argued that natural variations in tropical cyclone activity - on a regional, annual and inter-decadal scale - mask any signal from the impact of global warming, which remains relatively small.

Although there is no clear consensus on whether global warming is currently having any measurable impact on tropical cyclones, climate models indicate that there may be an increase in tropical cyclone intensity in the future, under continued global warming. However, the models also indicate that tropical cyclone frequency will either remain unchanged or decrease. A number of leading tropical cyclone scientists have come together to issue a statement endorsed by the World Meteorological Organization and publish latest research on the status of understanding and research into tropical cyclones and climate change.

WMO statement on tropical cyclones and climate change. Nature Geoscience article on tropical cyclones and climate change. Tropical Cyclone Frequently Asked Questions. Tropical cyclone facts.

However, tropical cyclones are essential features of the Earth's atmosp Introduction What is a tropical cyclone? How do tropical cyclones form? How does the tropical cyclone obtain its energy? How do they get their names? Where and when do tropical cyclones occur?