Why do typhoons occur in the philippines

Outside the radius of maximum wind, the anticyclonic relative vorticity is associated with a stress field with negative curl. Convergence is induced in the mixed layer and downwelling occurs, which also acts to deepen the mixed layer. As the radius of maximum winds passes, the vorticity becomes strongly positive, and a positive stress curl induces horizontal divergence of mixed-layer water and a strong upwelling. Behind the storm, the reverse sequence of events occurs.

In addition, imbalances between the current velocities and pressure field in the ocean lead to eddies which between the current velocities and pressure field in the ocean lead to eddies which persists far behind the storm. Since the eddy circulations in the ocean which are induced by tropical cyclones and the sea-surface temperature decreases may persist for many days after a storm's passage, the behavior of subsequent storms which cross the modified ocean surface may be affected, although the small area of significant sea surface temperature decreases makes a large influence unlikely.

In addition to the cooling of the ocean by upwelling and mixing, there are four other processes that may also affect the oceanic temperature. These include the following:. Radiative effects are negligible near the center because of the presence of thick, multilevel clouds which reflect most of the incoming short-wave radiation while blocking long wave radiation loss. As tropical storms make landfall, the combined action of the pressure anomaly and the wind stress produces the most destructive aspect of the hurricane to coastal regions - the storm surge.

Storm surge is the abnormal rise in sea level at the coast during the passage of an intense tropical cyclone TC , usually land falling or touching land. It is best described as the highest water level rise as the peak of the storm surges usually coincides with the time of passage of typhoon across a coastline.

The exact distribution and amplitude of the storm surge depend in a complicated way on the bottom topography as well as the size, intensity, direction and speed of movement of the tropical cyclone. In addition to the relatively simple barotropic and baroclinic responses that are produced over the open ocean, rapidly decreasing depths induce nonlinear responses as the perturbation depths become large compared to the mean depth.

Peninsulas and islands provide walls to reflect, refract and channel waves. Flooding of low-lying areas expands the area of the ocean and reduces the surge height in the waters adjacent to the coast. Storm swell is an indicator of an approaching tropical cyclone.

The appearance of a swell of a particular type may give quite reliable indications of a tropical storm as much as to kilometers or more distant. The height of the waves from which swell develop is determined by the fetch or water distance over which the wind has blown without significant deviation in direction.

The magnitude of waves is dependent not only upon the fetch, but also upon the wind velocity. Over oceanic areas with - miles or more of sea room, waves feet high are developed in ordinary storms and in more intense storms may exceed 45 feet. Based on some studies, the quotient obtained by dividing the wind velocity probably average for hour in miles per hour by 2.

This should be used with caution and only as an approximation. Since there are always other factors to be taken into consideration, and a wind, constant in speed and direction in a hurricane at least , does not act on a wave for any great length of time. The breaking wave or swell is one of the most destructive elements of tropical cyclone, since a cubic yard of water weighs pounds and waves moving forward many feet per second may be very destructive to beaches and harbor facilities, especially when they contain debris such as tree trunks and heavy beams.

During the occurrence of a tropical cyclone it was observed that the wind energy is concentrated in the storm causing a system of swell waves to spread out of the storm area. The swell moves with a speed of three or four times greater than the speed of the storm center. Now the swell generated in the rear right quadrant will move forward in the direction of the movement of the storm.

These waves will be under the influence of the strong winds for a long time, and we say that the fetch is large. To the left of the storm track, the waves are under the influence of the wind for a relatively short time, and we say that the fetch is small. The energy that goes into the swell increases with fetch, with result that the swell generated on the right of the storm becomes prominent.

This swell travels a long way, it may be observed as far as miles away from the center of the storm, and this provides a warning. The direction from which the swell arrives points toward the place where the swell was generated. The warning is, however, not very precise, for it provides no information on the behavior of the storm since the swell left it. Nevertheless, the arrival of the swell is a useful early alert to the man on the bridge, the harbor master, and the beach dweller.

The main energy source of a tropical cyclone is water vapor which is abundant in the oceans and seas. When the sun heats up the earth surface, water vapor evaporates into the atmosphere and condenses into water droplets, a great amount of heat energy, which is locked up in the water vapor, is released. This process is known as condensation. It is the reverse process of evaporation, which requires considerable amount of heat to evaporate water.

The heat energy absorbed by water during the process of evaporation is locked in the water and is released only when the same amount of water condenses back into the liquid state. Through this process, an average-sized typhoon will get an energy supply in one day equivalent to the energy release by 40, hydrogen bombs. By comparison, the energy released by one hydrogen is very small against the energy of a typhoon in one day.

Storms that form in the Indian Ocean — a separate "basin" from the Western Pacific — are known as cyclones. Facebook Twitter Email. Why is Philippines a hot zone for typhoons? Show Caption. Those upper atmospheric winds bring drier air into the center of a hurricane, which is "like throwing cold water on a fire," said Emanuel.

That's why Koppu didn't strengthen until recently. Wind shear kept the storm from reaching its full potential early in its formation. Read about how double and even triple hurricanes form.

While hurricanes are categorized based on their wind speeds, wind isn't typically the most dangerous part of such storms. It's the number one killer in hurricanes, Emanuel said. Sandy's storm surge flooded New York City's subway system and runways at the city's airports while damaging New Jersey's transportation system. Super typhoon Haiyan—the strongest typhoon on record to hit land—sent a wall of water nearly 25 feet 7. The storm surge ripped apart buildings and washed away entire towns.

Learn why this monster storm was so unusual. Emanuel likened a storm surge to a tsunami. One just happens to be caused by earthquakes tsunamis , while the other is generated by hurricanes. Flash flooding caused by intense rains is also a major killer, Emanuel said. Forecasters are predicting up to 40 inches centimeters of rain in some parts of the Philippines. The flooding has gotten so bad that rescuers have been unable to reach towns and villages in need.

The fear now is that because the ground is so saturated with water entire hillsides could collapse. The worrisome thing though, is that climate change will likely increase the frequency of "the high-end hurricanes," Emanuel said.

Those categorized as threes or above the scale tops out at five. The Filipino is basically of Malay stock with a sprinkling of Chinese, American, Spanish and Arab blood, and other ethnic minorities. Overview of Disasters Located along the typhoon belt in the Pacific, the Philippines is visited by an average of 20 typhoons every year, five of which are destructive.

Pinatubo June Volcanic eruption of the Mount Pinatubo in June was the largest volcanic explosion in the 20th century. It killed , affected 1,, About 40, houses were destroyed, and more than 70, houses were damaged.