A typhoon is a region-specific term given to a type of tropical cyclone, usually occurring within the northwestern region of the Pacific Ocean, west of the International Date Line. These same systems in other regions are referred to as either hurricanes, or more generally, tropical cyclones. The center of a cyclone is referred to as the eye. The eye is a circular area of calm, fair weather. On average, a tropical cyclone eye is about 30 miles across. Surrounding the eye are eyewalls which are regions of dense convective clouds. The winds of eyewalls are the highest and generally cause the most damage. Spiraling into the eyewalls are more convective cloud regions referred to as spiral bands. These areas contain heavy winds and extend out from the typhoon eye.
How Typhoons Form
Typhoons or hurricanes form in hot, humid conditions over the ocean when winds traveling in opposite directions meet, a phenomenon known as convergence. As the opposing winds collide, hot air is forced upward and cools to form storm clouds. Usually these storms produce nothing more than lightning or a period of heavy rain, but in some cases high pressure and wind in the upper atmosphere can allow the hot air to continue its upward motion for a sustained period, creating a much stronger type of storm. A hurricane’s wind is caused by air rushing up from the surface of the ocean to replace air blown away in the upper atmosphere. Due to the Coriolis effect, which can affect the direction water drains down a sink, hurricanes in the northern hemisphere spin anti-clockwise, while in the southern hemisphere they spin clockwise.
When Typhoons Occur
According to the National Oceanic and Atmospheric Administration (NOAA), high winds push the surface of the waters ahead of the system on the right side of its path and cause over 85 percent of the cyclone’s surge.
In order to occur, tropical cyclones generally require ocean temperatures of at least 80 F. The systems begin with heat generated from spiraling water vapor in the atmosphere. This spiraling vapor forms into the convective clouds discussed earlier. Typhoon incidence rate is correlated with sea-surface temperature. Because of this, there may be a connection between global warming and tropical cyclones; as the temperature of the waters increase, so does the incidence of tropical cyclones. Typhoon season is typically between late June until sometime during the month of December.
Effects of Typhoons on:
Buildings and Infrastructure The two most destructive forces associated with typhoons are wind and rain. According to the Green Fun website, typhoon winds can affect buildings and other structures in two ways: through direct force and through projectiles. Direct force is when a wind gust slams directly into a building or structure and causes physical damage, such as when wind blows the roof off a home. Wind can also inflict damage by picking up and launching debris and other items, such as tree branches and building materials, into buildings and other structures. The heavy and persistent rainfall that typhoons bring can also have devastating effects. In addition to making homes uninhabitable, the flooding associated with typhoons can make roads impassable, which can cripple rescue and aid efforts.
Trees and Other Vegetation Typhoons can also affect the natural environment, and cause harm to trees and other vegetation, including crops that communities may rely on for sustenance or trade, or both. Strong winds can snap branches; detach and injure leaves, flowers, fruits and seeds; and uproot trees and plants. Flooding can produce over-saturation and drown out vegetation. Typhoons also deposit large quantities of salt onto plant life, which can have adverse effects. According to the Green Fun website, trees and vegetation in urban areas are more susceptible to typhoon damage, as they tend to grow in poor, restricted soil conditions.
• Watercraft and Water Operations In addition to causing mayhem on land, typhoons are also well-known for stirring up the seas. Individuals on watercraft or those performing water operations (such as on oil rigs) not only have to contend with heavy winds and rain, but they have to deal with massive waves and, in general, turbulent water conditions. According to the Naval Historical Center website, typhoons have a history of causing harm out at sea, and this was especially true during World War II, when Pacific naval fleets were regularly battered by the storms. Today, fishing boats, cruise ships and other vessels rely on sophisticated technology to help them predict and avoid the devastating effects of typhoons.
• Life Both human and animal life can be impacted, and ultimately taken, by the destructive forces of typhoons. While this can occur directly, such as if an individual is struck by debris or is caught in a building collapse, perhaps the more silent killer is the lack of available resources and infrastructure that results. Flooding from typhoons can destroy food stocks and supplies, and spread disease. When communities are cut off by typhoons, individuals may not be able to get the medical attention they so desperately need, and starvation becomes a big risk as well.