What Are Typhoons?
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 Occur
Researchers are continuously working toward and discovering new information on the phenomena of tropical cyclones as there is still much regarding the system that is unknown. Typhoons occur when a rough weather wave, using the Earth's rotation, begins to rotate (also known as the Coriolis effect). The potential of generating a pressure system increases if this wave spins into a complete circle; with higher pressure on the outside and a low-pressure center. High multidirectional winds surrounding the wave can disrupt the system from forming. If the system maintains its rotation and begins to spiral at a rate greater than 65 knots (74 mph), it is referred to as a tropical cyclone. Typhoon intensity is not dependent on the size of the system.
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.