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Sunday, May 26, 2019

The origin of hurricanes and predictability of hurricane tracks

Low pressure systems give at mid latitude temperate zones as a result of the convergence of flying and cold mail masses. Low pressure systems generally form over the polar front where the polar maritime strip (a cold direct mass) and equatorial maritime channelize (a warm contrast mass) meet. aureole currents in this area within the Northern Hemisphere depart f depressed counter-clockwise delinquent to the rotation of the earth and surface friction. Air flows accumulate at the centre of the system, and the warm distribute rises because it is less dense, leading to low pressure at the surface.It contains more moisture than the polar maritime air and as a result, when it ascends, it condenses and produces clouds and rain. Cirrus type clouds are the first clouds that are usually created at this point. A circulation of air rotates in an anticlockwise motion due to the coriolis effect. The tropical maritime air swirls around the polar front, the system matures and eventually a warm and cold front is created.At the warm front, the warm air rises over the cold air, the cirrus clouds develop to be cirrostratus, altostratus and nimbostratus clouds which eventually will lead to heavy rain because of the condensation of the warm air. Towards the edge of the warm front, conditions are more stable and pressure stops decreasing as much. No longer is thither so much condensation and therefore there is less rain. Polar maritime air is fast, dense, and strong. Eventually the air pushes in and forces the warm air off the ground, creating instability.The pressure increases, as the air ascends rapidly, cumulonimbus clouds form bringing in heavy rain and storms1. The cold front consists of heavier and denser air and displaces the warmer and lighter air, because of this, it moves faster than the warm front and it will ultimately hoodwink up with it. Warm air is forced off the ground by the cold air, and once this happens, an occlusion is created. Uniform air protrudes to fill the gap betwixt the warm front and the cold front and this is where the low pressure system begins to die away.At tropical latitudes, if sea surface temperatures are above 27 degrees c2, then the low pressure system will grow. If the conditions are right, tropical thunderstorms may develop to become a hurri stinkpote. Low pressure systems often begin to rotate around a central area of low pressure. This is known as a tropical depression, if the depression increases in intensity so that winds remove at least 39 mph, its categorised as a tropical storm. If wind speeds reach and average of 74 mph3, it known as tropical cyclone or hurricane.Hurricanes/ tropical cyclones mainly develop in the region between 10 and 20 degrees North of the equator (Goldenberg, 2001). When a storm grows to become a hurricane/tropical cyclone, it is depict as a non-frontal low pressure system4 and can reach up to 340 miles across in diameter5. Hurricanes absorb energy from the warm water of the o cean, and a thunderstorm will continue to grow so long as there is a fuel source i. e a supply of moist air and heat.This source is normally make up above the water in tropical waters. When the heat supply is cut off i. when the hurricane begins to migrate northwards (or southwards), over colder water, it will weaken and die away. Heat from the oceans is the primary source of energy for hurricanes, 6and so, the greater the heat of the SST 7the more intense and frequent hurricanes in that area will be (Goldenberg, et al, 2001).Hurricanes dont usually develop far inland due to the lack of moisture. 8 If there is no moisture, then clouds are not likely to form. Cloud formation results in the generation of latent heat. Latent heat is the heat needed to initiate a change of phase i. to a state of higher energy, e. g. from solid to liquid, or liquid to gas, in this context though, its from liquid to a gas. As clouds are not generated as much, then not much latent heat is released. the bu lk of hurricanes originate and stay within the oceans, though they do occasionally travel inland, and the effects they can have on the environment, society and on the economy of the abnormal area are potentially devastating. The coriolis effect, which is a product of the earths rotation is the reason that storms rotate and why a hurricane has a typical swirling formation.The rotation of the storm causes air to be drawn into the extreme low pressure at the centre (eye) of the storm. As the air rotates, the air ascends. The rising air is very moist, the higher the altitude, the colder the temperature, and so, it condenses forming clouds. Hurricanes arent found within 0-5 degrees north and south of the equator ((300 miles (500 kilometers)) of the equator because the coriolis effect is at its weakest at this point, so the storm doesnt have enough spin, and there isnt enough force to maintain low pressure in the centre of the system.Meteorologists can predict hurricanes in two main ways through the use of seasonal probabilities and tracking of hurricanes that are in existence at a current point of time using modelling techniques9. Annually, scientists work out how many storms are likely to develop into hurricanes/tropical storms and they also calculate how many are likely to make landfall. Using statistical techniques such as CLIPER10, past data, and by sending aeroplanes into the centre of storms they can determine wind speeds, temperatures and can predict the intensity of a hurricane, and how many people it is likely to affect.Many scientists try and determine the paths of hurricanes, and its a difficult profession because not all hurricanes have defined paths, however the typical characteristics and properties of the weather and ocean in a specific area allow scientists to have a rough idea to which path a hurricane is likely to follow. If the path is predicted then warning and protection can be provided for those that could potentially be affected and this i s the outmatch way to prevent a social, economic and environmental disaster from happening.Hurricanes form in various areas depending on the various times of the hurricane season (Reading, 1990). Tracks can be predicted efficiently however, accuracy seems to be an issue in many cases. Models have become more accurate (NOAA,2004) and prediction techniques have improved (Aberson,2001), however there is still a large uncertainty and error is still an issue. It is easier to predict exactly where a hurricane is going to make landfall the closer to landfall the storm is.So the merely the hurricane is away from land, the more error there is when trying to work out its path (NOAA,2004). This is mainly due to natural changes in the storms physical characteristics. It has been determined by NOAA, that, 5 days before landfall there is an average of 350 miles of error, and one day before landfall there is a 100 mile error, 11which is a major conundrum because a difference of that mileage cou ld determine whether or not whole cities or villages need to be evacuated or not, and if there is an error, it could be devastating.

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