“The calamity that comes is never that one we had prepared ourselves for.” — Mark Twain
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“Oftentimes, we make the mistake of interchanging climate and weather, but they are actually two different things,” said Dr. Jorge G. de las Alas, a professor of the Institute of Environmental Science and Meteorology at the University of the Philippines in Diliman, Quezon City.
Climate, Dr. de las Alas explained, is the statistical average of observed weather in a particular area of interest over a relatively long period of time. “Climate is not static,” he said. “It is ever changing like weather but its rate of change is small and generally imperceptible in periods comparable to man’s lifetime.”
In a recent climate forum for agriculture convened by the Department of Agriculture and UN Food and Agriculture Organization in Davao City, Dr. Anthony Joseph R. Lucero bared the Philippines has four types of climates.
“Davao City and the rest of Davao Region is under the Type IV,” Dr. Lucero, senior weather specialist of the state-owned Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), pointed out. “The rainfall in these areas is more or less evenly distributed throughout the year.”
Other places in the country which has the same type of climate are Camarines Sur, Leyte, Bohol, Misamis Oriental, South Cotabato, Zamboanga del Sur, Sulu and Tawi-Tawi.
Areas with Type I have two pronounced seasons: dry from December to May and wet from June to November. Maximum rain period is from June to September. Areas characterized by this climate type are Ilocos Norte and Sur, Abra, La Union, Benguet, Nueva Ecija, Pangasinan, Tarlac, Zambales, Pampanga, Bulacan, and Bataan.
Metro Manila, Cavite, Batangas, Mindoro Occidental, Iloilo and the western section of Palawan have also this type. So do parts of Mountain Province, Ifugao, Nueva Vizcaya, Antique and Negros Oriental.
Those with Type II have no dry season with a very pronounced maximum rain period from December to January. Places with this type include Northern and Eastern Samar, Agusan del Sur, and some parts of Davao Oriental.
Seasons in areas with Type III are not very pronounced. It is relatively dry from November to April and wet during the rest of the year just like in Isabela, Rizal, Laguna, Aklan, Cebu, Bukidnon, and North Cotabato.
“Climate is what you expect,” said American humorist and novelist Mark Twain, “weather is what you get.”
Dr. Lucero seemed to agree with Twain’s observation when he said that climate in a particular place has been firmly established while the weather is a lot more unpredictable because “it has to do with the day-to-day changes in atmospheric conditions.”
The Philippines, given the location and the topography of the country, experiences several weather-causing phenomena: thunderstorm, cold front, monsoons, easterly wave, intertropical convergence zone, low pressure area, and tropical cyclone.
Thunderstorms, called local storms, occur when towering cumulus clouds reach a height where the temperature is well below the freezing point. Among the associated hazards are heavy rain (which may cause flashflood) and lightning (which may cause death, burns or fire).
Cold front, which is prevalent in temperate countries, is formed when cold air moves over areas of warm air. Since cold air is heavier than warm air, the warm air is pushed aloft by the cold air giving rise to widespread cloudiness.
“Cold front does not pass the country’s area of responsibility,” said Dr. Lucero. “What we have is only the tail of the cold front. It is very unique in the Philippines as we have a weather that gives us cooler temperature. There is no such thing in our neighboring countries like Indonesia, Malaysia, and Singapore.”
A monsoon (from the Arabic mawsim, which means “season”) often brings about thoughts of torrential rains, similar to a typhoon. “But there is a difference: a monsoon is not a single storm; rather it is a seasonal wind shift over a region,” writes Rachel Ross, a Live Science contributor.
The Philippines experiences two types of monsoon: Southwest and Northeast. In the former, the Asiatic continent becomes warmer than the surrounding seas and a low-pressure cell develops over the continent. This causes a flow of moist southwest wind over the Philippine area. At times, when this southwest flow becomes thick in depth, it persists for a long period causing continuous rains which may last for weeks during the months of June to September.
The Southwest monsoon, locally called habagat, is responsible for the great portion of rainfall during the country’s wet season. “About 60% of the rainfall in the Philippines is associated with Southwest monsoon,” Dr. Lucero said.
The Northeast monsoon is known locally as amihan. “Northeast monsoon is a wind system that reverses in direction, from the southwest to the northeast,” Dr. Lucero said. “It originates in mainland Asia (particularly those in Siberia) and crosses the Philippines in northeast direction. During the amihan, malamig ang panahon sa Pilipinas, which is usually from October to March.”
Easterly waves are meanderings (waves) in the wind, which blows from the east. Some storms and minor typhoons originate from easterly waves. “Mahina ang hangin na dala ng easterly waves and it is easily overcome by Southwest and Northeast monsoons,” Dr. Lucero said.
The intertropical convergence zone (ITCZ), for the information of the uninformed, is an area where the northern hemisphere trades meet the southern hemisphere trades. According to the weather bureau, ITCZ is characterized by towering clouds of cumulonimbus clouds accompanied with showers of widespread thunderstorms.
“The axis of convergence, which is usually oriented in an east to west direction, does not remain stationery at the equator but migrates north or south of the equator,” the country’s weather bureau explains. In the Philippines, it oscillates during the months of May to October.
During the ITCZ, low pressure area (where the atmospheric pressure is lower than that of surrounding locations) is embedded. And once ITCZ leaves, low pressure area is left behind. Low-pressure systems, it is said, form under areas of wind divergence which occur in the upper levels of the troposphere, the lowest layer of Earth’s atmosphere.
This brings us to tropical cyclones. These are low pressure systems characterized by relatively low atmospheric pressure at the center with very strong winds blowing counterclock wise (in the northern hemisphere) towards and around the center.
In the Filipino dialect, tropical cyclones are called “bagyo,” a word which came after a 1911 storm in the city of Baguio, which had a record rainfall of 46 inches within a 24-hour period.
There is no month in the Philippines which is free from typhoons. Records show an average of 20 out of 36 tropical cyclones that develop over the Northwest Pacific cross the country every year. But less than half of those cyclones are expected to make a landfall.
Among the dangers associated with typhoons are heavy rainfalls and floods, strong winds, storm surge, landslides and mudflows. “Landslides can bury people alive and destroy properties,” the weather bureau reminds. “Mudflows, on the other hand, are hazardous to people and properties, too.”
Weather specialists all agree that the Philippines need to be a step ahead of any impending typhoons through timely and accurate weather forecast. This can be accomplished through the Deployment of Early Warning System (DEWS) in disaster-prone areas. DEWS is a collaborative effort of several agencies of the Department of Science and Technology (DOST) including PAGASA, Advanced Science and Technology Institute (ASTI) and DOST regional offices.
“The DEWS Project aims to deploy hydrometeorological devices (hydromets) and warning stations in selected hazard areas in the country for disaster preparedness and mitigation,” wrote Judy A. Aca-Saclamitao in a feature published in S&T Post.
Hydromets like automated rain gauge and water level monitoring station are installed in different river systems and secondary tributaries to help scientists obtain data that can be used in protecting the lives, properties, and livelihood projects in various communities.
Complementing these modern hydromets are traditional early warning systems such as sirens and beacons. “The use of sirens or beacons as early warning of natural hazards is one of global best practices in informing unsuspecting communities,” May Celicious-Cabayan, an ASTI official, was quoted as saying.
