Hurricanes usually take a matter of days to develop from a depression to a hurricane, but this time period can vary. For hurricane formation to take place, warm waters of temperatures higher than 27 degrees Celsius must be present. From these warm waters, evaporation takes place at a high rate. Warm, moist air above the ocean surfaces rises via convection currents. As this air rises it condenses and storm clouds form. During condensation, energy is released in the form of heat, known as latent heat of condensation. Latent heat of condensation powers a hurricane. This latent heat warms air and causes it to rise. The risen air is replaced by more warm moist air from the ocean surfaces. This process is repeated continuously in a cycle. As heat is transferred from the surface to the atmosphere continually, a circular wind pattern (counter-clockwise in the N. Hemisphere) is formed. Converging winds and pressure gradient also help in hurricane formation as they cause warm, moist air to rise, causing low pressure and circular wind patterns also.
A hurricane is made up of three main parts: the eye, the eye wall and the rain bands. The eye is the calm region found to the centre of the hurricane. Here, pressure is at its lowest (sometimes 960 millibars). Conditions at the eye are dry and not very windy. The eye wall surrounds the eye and is made of thick cumulonimbus cloud. Here, winds are most intense and rainfall heaviest. The rain bands are made of many thunderstorms circulating out from the eye. These play a roll in the evaporation/ condensation cycle, which provides the system with energy.
Figure 1: Structure Of A Hurricane
Hurricanes are perhaps the most devastating natural disaster affecting the Earth today. They have a major impact of the physical and human environments.
The physical environment can be defined as the structural features of the land, air and sea. The passing of a hurricane is always destructive to this environment. Most of the destruction is caused by the high-velocity winds and torrential rainfall that occur.
These high-velocity winds along with low pressure lead to the formation of storm surges (tidal waves). Tidal waves, sometimes many metres tall, crash against coastal areas; eroding beaches and damaging coastal homes and buildings. Tidal waves also cause major damage to boats anchored in harbours.
Figure 2: A Tidal Wave
Figure 3: Barne’s Bay Eroded after Hurricane Luis
Strong gusts of winds easily uproot trees, bushes and other vegetation types. The pressure of the wind against the trees is so many Newtons per squared metre that the trees have no choice but to go down. Since many animals live in trees and bushes. Many habitats are destroyed. The damage to vegetation also affects the carbon dioxide to oxygen ratio in the atmosphere and also accelerates soil erosion, as fewer roots are present in the soil.
Powerful, destructive winds also push down communication poles, causing communication and utility lines to snap. Hurricane winds are also agents of pollution. They strip materials off buildings, vehicles etc. and deposit them at sea, on the coast and other sites.
The torrential rains (and sometimes tidal waves) are responsible for the flooding that occurs during hurricanes. Flooding is a natural disaster in itself. Houses and vehicles are swept away during a flood, possessions are destroyed and water supplies are polluted.
Figure 4: Flooding after Hurricane hits Haiti
Heavy torrential rainfalls on a heavy unstable mountainside/ hillside can cause the occurrence of mudslides and landslides. If these occur buildings and crops are destroyed.
Together, torrential rains and powerful winds, batter homes and other buildings, sometimes completely destroying them. They also bring on the death of crops and livestock, usually by uprooting and drowning respectively. The rains and wind can often damage road and bridges and other carriageways.
Figure 5: Houses Destroyed By Severe Winds.
The human environment is the people that inhabit the Earth. Hurricanes impact on the human environment in a largely negative way. Due to the destruction of homes, many people are left exposed during hurricanes. Many of these people often die and survivors are usually very ill with pneumonia. Death tolls tend to be high and can range from under a hundred to hundreds of thousands.
Repair and restoration of damaged buildings and reconstruction of destroyed buildings can cost a country millions to billions of dollars. This greatly affects the economy and financial situation of a country. It also affects the lives of the citizens as the rebuilding process can take many years.
Polluted and contaminated water supplies cannot be used. If they are diseases and infection can be contracted and spread.
Damaged roads and workplaces make everyday functions had to carry out. Trade and exchange are disrupted and life is made uncomfortable.
The breakage of communication and utility lines is a major inconvenince to a people. They have to find means of living without electricity, telephone and sometimes television.
The destruction of crops and livestock has a profound effect on the human environment. These provide food sources for people. When hurricanes occur, fields of crops can be lost and many animals can die. When this occurs there are food shortages and hunger and starvation increases, causing an increase in crime.
In conclusion, hurricanes have a negative impact on both the human and physical environment. They are natural disasters, which cannot be prevented or stopped from occurring. Due to technological advancements made in the last few decades though, hurricane formation can be spotted very early and their progress tracked and predicted. Hurricane warnings are then issued to places possibly and definitely in danger. Warnings give people time to reinforce their homes by boarding up etc, to stock up on food supplies and to move to “safer locations” if necessary and possible.
Nonetheless, you can never guarantee your safety in the world’s greatest natural disaster, the hurricane.
