CLIMATE

HUMIDITYRefers to the moisture of the atmosphere. When the temperature is warm and the place is near of the

bodies of water, more moisture is evaporated to form cloudsRELATIVE HUMIDITY- is the ratio of the actual moisture

content of the atmosphere to that which it can hold to be saturated at the same temperature.

3.4

Rev. Father CoronasRelative humidity in the Philippines is mainly due to extraordinary evaporation from the seas that surround them on all sides, to the richness of vegetation, to different prevailing winds in different seasons of the year and to the abundant rains so proper to a

tropical country. The first two general causes of great humidity are generally observe in all islands throughout the year. The first two general causes of the great humidity are generally observed in all islands throughout the year. The other two influence in different degrees the humidity of the different regions of archipelago. In

winter, when the rains are so abundant in the eastern part of the Philippines owing to the prevailing northeasterly winds, humidity is

greater than in the western part where the dry season prevails. From June to October, rains are more abundant in the western part

which is more exposed to prevailing westerly and southwesterly winds, hence , humidity is greater than in the eastern part.

RAINFALLRainfall is more important in the Philippines as a climatic element

than temperature .Rainfall distribution throughout the country varies from one region to

another due to topography and the wind systems .During the cool months, the rains in the Philippines are mainly due to

north-easterly air currents which come directly from the pacific ocean causing rainfall over the eastern part of the archipelago. These are the so-called northeast-monsoon rains.

3.5

AVERAGE RAINFALL IN THE PHILIPPINES BY KEY STATIONS FROM 1965 TO1970. STATIONS (IN

MILLIMETERS) MONTHS LAOAG MANILA LEGASPI PUERTO

PRINCESACEBU DAVAO

JANUARY 1.6 9.4 351.8 41.8 122.9 147.2FEBRUARY 0 5.5 142.9 11.2 49.2 94.9MARCH 1.0 4.6 182.9 32.9 33.8 86.2APRIL 23.5 17.3 125.2 33.9 28.8 114.8MAY 169.7 147.3 106.4 131.3 77.7 234.0JUNE 439.1 245.0 176.8 149.5 192.7 135.4JULY 380.4 346.7 283.4 199.0 171.9 150.0AUGUST 538.5 389.4 288.8 212.1 165.6 176.0SEPTEMBER

528.5 509.6 283.4 197.0 123.0 180.6

OCTOBER 78.3 158.8 301.3 197.0 123.0 180.6NOVEMBER 63.3 95.5 494.1 270.0 170.0 142.0DECEMBER 5.7 35.5 488.1 80.1 80.0 99.6TOTAL 2,229.6 1,964.6 3,225.2 1,646.8 1,376.1 1,738.7

BASED ON THE DISTRIBUTION OF RAINFALL, FOUR CLIMATIC TYPES ARE RECOGNIZED.

THESE CLIMATIC TYPES ARE DESCRIBED AS FOLLOWS:

TYPE 1- two pronounced wet and dry season; wet during months of June to November and dry from December to May. This type of climate is found in the western part of Luzon, Mindoro, Palawan, Panay and Negros. The controlling factor is topography. These regions are shield from the northeast monsoon ranges, but are open to the southwest monsoon and cyclonic storms.

TYPE 2- No dry season with a very pronounced maximum rain period in December, January and February. Catanduanes, Sorsogon, Eastern part of Albay, Camarines Norte, Camarines Sur, Eastern Quezon Samar, Leyte and Eastern Mindanao have this type. These regions are along or very near in the eastern coast and are not sheltered either from the northeasterly and trade winds or from the cyclonic storms.

TYPE 3- This is an intermediate type with no pronounced maximum rain period and a short dry season lasting from one to three months only. Areas under this type are the western parts of the Cagayan Valley, the eastern part of the Mountain Region, Southern Quezon, Masbate, Romblon, Northeastern Panay, Eastern Negros, central and southern Cebu, eastern Palawan and Northern Mindanao. These localities are only partly sheltered from the northeasterly and trade winds and are open to the southwest monsoon or at least to frequent cyclonic storms.

TYPE 4- Uniformly distributed rainfall. The regions affected by this type are the Batanes, Northeastern Luzon, Southwestern part of Camarines Norte, Western part of Camarines Sur and Albay, Bondoc, Peninsula, Eastern Mindoro, Marinduque, Western Leyte, Northern Cebu, Bohol and most of Central, Eastern and Southern Mindanao. These regions are so situated that they are open to the northeasterly and trade winds as well as the southwest monsoon and the cyclonic storms.

PRESSURE AND WINDSCompared to temperature and rainfall, Pressure and winds are

relatively insignificant as elements of weather and climate. Although winds of high velocity are dangerous to crops and buildings, the sum total of the direct effects of the winds on man is less significant.

The higher the difference the greater is the velocity of the wind. Pressure and winds exert a profound effect on the temperature and

precipitation. A minor change in pressure may cause a change in the velocity and direction of the wind. A change in the movement of the wind may produce changes in temperature which may in turn affect precipitation.

3.6

•There are three important air movements in the Philippines:(a) trade winds

- originate in the high pressure area of the eastern north pacific ocean.(b) southwest monsoon

- is the deflected southwest trades of the southern hemisphere.(c) northeast monsoon

- which is often times called northern, blows during the month of November to February. This is the period when it is winter in the northern hemisphere.

•Trade winds

•Southwest Moonsoon

•Northeast Moonsoon

Thank you :)