The objective is to make the information more understandable to the public and make them react through the visual impacts of short video. Skip to main content. FAQs - Tropical Cyclones isabelzb. FAQs - Tropical Cyclones. Tags: Emergency. Natural hazards. What is the difference between "hurricane", "cyclone" and "typhoon"?
Storm surges tidal waves are defined as the rise in sea level above the normally predicted astronomical tide. Major factors include:. The very high specific humidity condenses into exceptionally large raindrops and giant cumulus clouds, resulting in high precipitation rates. When a cyclone makes landfall, rain rapidly saturates the catchment areas and the rapid runoff may extensively flood the usual water sources or create new ones.
Formation and Initial Development Stage The formation and initial development of a cyclonic storm depends upon various conditions. These are:. Mature Tropical Cyclones When a tropical storm intensifies, the air rises in vigorous thunderstorms and tends to spread out horizontally at the tropopause level. Once air spreads out, a positive perturbation pressure at high levels is produced, which accelerates the downward motion of air due to convection.
The main physical feature of a mature tropical cyclone in the Indian Ocean is a concentric pattern of highly turbulent giant cumulus thundercloud bands. Modification and Decay A tropical cyclone begins to weaken in terms of its central low pressure, internal warmth and extremely high speeds, as soon as its source of warm moist air begins to ebb, or is abruptly cut off. This happens after its landfall or when it passes over cold waters. The weakening of a cyclone does not mean that the danger to life and property is over.
These trigger mechanisms depend on several conditions being 'right' at the same time. The most influential factors are:. The Coriolis force caused by the rotation of the Earth helps the spin of this column of rising air. The development of the surface depression causes an increase in the strength of the trade winds.
The spiralling winds accelerate inwards and upwards, releasing heat and moisture as they do so. As the depression strengthens it becomes a tropical storm and then a hurricane or typhoon. A mature hurricane or typhoon takes the form of a cylinder of deep thundercloud around a centre that is relatively free from clouds. There is a relatively small area of intense horizontal winds at the surface, often well over m.
Further aloft at about six miles, the cloud tops are carried outwards to give thick layer clouds due to the outward-spiralling winds leaving the tropical cyclone core. At the centre of the tropical cyclone, air is subsiding, which makes it dry and often cloud free, and there is little or no wind at the surface. This is called the eye of the storm. Great amounts of energy are transferred when warm water is evaporated from tropical seas.
This energy is stored within the water vapour contained in moist air. The release of heat energy warms the air locally, causing a further decrease in pressure aloft. Consequently, air rises faster to fill this area of low pressure, and more warm, moist air is drawn off the sea, feeding further energy to the system.
Thus, a self-sustaining heat engine is created. This relatively small amount of mechanical energy equates to a power supply of 1. Tropical cyclones are named to provide ease of communication between forecasters and the general public, regarding forecasts, watches and warnings. Since the storms can often last a week or even longer, and more than one can be occurring in the same region at the same time, names can reduce the confusion about what storm is being described.
Names were first used widely in World War II and were subsequently adopted by all regions. In most regions pre-determined alphabetic lists of alternating male and female names are used.
However, in the western North Pacific and North Indian Oceans the majority of names used are not personal names. While there are a few male and female names, most are names of flowers, animals, birds, trees, foods or descriptive adjectives. The names are also not allocated in alphabetical order, but are arranged by the name of the Asian country which contributed the name. Many tropical cyclones eventually drift far enough from the equator to move into areas dominated by westerly winds found in the middle latitudes.
These winds tend to reverse the direction of the tropical cyclone to an eastward path. As the tropical cyclone moves polewards it picks up forward speed and may reach 30 m. An average tropical cyclone can travel about to miles a day, or about 3, miles before it dies out. Tropical cyclones also occur in various parts of the Pacific Ocean, and can affect coastal regions of Mexico, south-east Asia, north-east Australia and the south Pacific islands.
In the northern hemisphere most tropical cyclones occur between June and November with a peak in September. However, in the western North Pacific it is not unusual to have the occasional tropical cyclone outside of this period.
In the southern hemisphere the season usually lasts from November to April. By any name, they are the most damaging storms on Earth.
Hurricanes arise in the tropical latitudes between 10 degrees and 25 degrees N in summer and autumn when sea surface temperature are 28 degrees C 82 degrees F or higher.
The warm seas create a large humid air mass. The warm air rises and forms a low pressure cell, known as a tropical depression. Thunderstorms materialize around the tropical depression.
If the temperature reaches or exceeds 28 degrees C 82 degrees F the air begins to rotate around the low pressure counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. As the air rises, water vapor condenses, releasing energy from latent heat. If wind shear is low, the storm builds into a hurricane within two to three days.
Hurricanes are huge with high winds. The exception is the relatively calm eye of the storm where air is rising upward. Rainfall can be as high as 2. The release of latent heat generates enormous amounts of energy, nearly the total annual electrical power consumption of the United States from one storm. Hurricanes can also generate tornadoes.
Hurricanes are strange creatures because they are deadly monsters, yet have a gentle, but cold heart. The anatomy of a hurricane is fairly simple, though the processes involved are quite complex.
As a low pressure disturbance forms, the warm, moist air rushes towards the low pressure in order to rise upward to form towering thunderstorms. Around the low pressure disturbance is a wall of clouds called an eye wall.
Within the eye wall, the wind speeds are greatest, the clouds are the tallest, atmospheric pressure is at its lowest, and precipitation is most intense.
At the center or heart of the hurricane is called the eye. Within the eye of a hurricane, winds are light, precipitation is minimal, and occasionally the skies above are clear.
It is the calm region of the tropical storm, but that is what makes it so dangerous.
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