Weather patterns in the phillipines
- 1. WEATHER PATTERNS IN THE PHILIPPINES By: Shawn Daniel V. Francisco
- 2. Factors Affecting Weather Weather is the condition of the atmosphere at a given time in a particular place. The vertical scale of weather system is much more limited in the troposphere because pressure and temperature decrease so rapidly. Temperature varies based on the altitude. The higher the altitude, the lower the temperature. Temperature decreases with height at an average of -3.6°F (-19.778°C) per 1000 Feet (304.8 Meters) Reaching about -80 °C or -110°F above the tropical regions. When the sun warms the Earth, it gets unequal distribution of heat. Air at the equator is warmer than the air at the poles. The uneven heating of the regions of the troposphere by the sun causes convection currents. When warm, moist air rises and meets colder temperature, water vapor condenses. Water vapor forms precipitation like rain or snow that falls to the earth.
- 3. Elements of Weather Changes Weather changes from time to time. Changes in humidity, cloudiness, air temperature and wind and air pressure cause a change in the weather. These elements contribute to different weather systems, such as areas of high and low pressure, monsoons, thunderstorms and tornadoes. Changes in the temperature and humidity affect the other elements and cause the change of weather.
- 4. Temperature Is a measure of the degree of hotness or coldness of the air. Temperature on Earth averages 15°C (59°F) at sea level (0m). However it varies according to the elevation, location of the place and time of day. The higher elevation, the lower the temperature. Temperature also differs according to the latitude or location of place in the globe. Places near the tropics and equator have high temperature compared to the poles. It is usually warm during mid-afternoon and cold around dawn.
- 5. Humidity Is a measure of moisture present in the air. The air’s capacity to hold water vapor is limited but increases severely as the air warms. When the temperature of the atmosphere is high, the water in Earth’s surface evaporates rapidly. So the amount of water present in the air is high. The amount of water vapor in the air contributes to the change of weather. High water vapor in the air means precipitation could occur. Air relative humidity differs in time of day. The air relative humidity is high around dawn when the temperature is low. It is low in the afternoon when the temperature is high. This happens when the amount of water vapor in the air is constant. The relative humidity decreases as the air is heated and it increases as the air is cooled.
- 6. Precipitation Is any form of moisture including rain, drizzle, snow, freezing rain, hail and ice pellets, or sleet that falls on the ground. Precipitation usually forms when clouds reach the thickness of more than one kilometer. When droplets and crystals in clouds grow large and the clouds cannot hold them, they fall to the ground as precipitation. The precipitation that usually occurs in the Philippines include rain, drizzle, and hailstones.
- 7. Wind Is the horizontal movement of air near Earth’s surface, wind speed near the ground has an average range from 8 to 24 km/h(4.97097 to14.9129mph). The wind speed can be much higher during intense storms. In the northern and southern hemispheres where west wind occurs, the speed of the wind increases with height up to the top of the troposphere. The center of the most rapid winds at the top of the troposphere forms a jet stream. Near the ground, the air blows at an acute angle. It blows toward areas of low pressure, forming cyclones and anticyclones. It is slowed by friction when it comes in contact with the earth’s surface.
- 8. Pressure Is the continuous physical force exerted on against an object by something in contact with it. It plays a vital role in all weather systems. Large regions in the atmosphere that have higher pressure than the surroundings are called high- pressure areas. Regions that have lower pressure than the surroundings are called low-pressure areas. Most storms occur in low pressure areas. Low-pressure areas usually occur in warm oceans during summer seasons. In a barometer, rapidly falling pressure usually means a storm is approaching, whereas rapidly rising pressure usually indicates a clear sky.
- 9. Factors Affecting Weather Patterns in the Philippines Is a large body of air that has characteristics similar to the region of Earth’s surface over where it develops. Air mass extends across areas of Earth and is a thousand feet thick. The location of the air mass where it is developed determines its characteristics. Air mass that develops over tropical oceans is hot and humid. Air mass that develops in continents covered in ice is cold and dry. Air Masses
- 10. Air mass can cover thousands of square miles. It can even cover an entire country. There are two air masses that pass over the Philippines and affect its weather. During April to early October, the air mass formed over warm Equatorial ocean brings hot and humid air. This warm air mass, when passing over the country, brings heavy rains and typhoons. During November to February, cool and dry air mass forms over Siberia and northern China passes over the Philippines. This cold air mass brings cold and dry season in the country. So when you observe a change in weather from one day to the next day, it is due to the movement of air mass.
- 11. Fronts Are boundaries between two air masses of different densities, moisture, or temperatures. It can be classified geographically according to the motion of the air mass. Storms, precipitation and cloudiness sometimes occur at frontal boundaries. Four types include cold, warm, occluded and stationary.
- 12. Warm Fronts Are boundaries along a warm air mass pushing out a cold air mass. A warm air mass is usually light. When it moves over a cold mass, a warm front is formed. When a warm front moves forward, high cirrus clouds appear, followed by stratus and nimbus clouds. The presence of clouds in the sky brings steady rains. When a front passes by, the sky will become clear. Temperature rises as warm air replaces cold air. You can observe changes in air pressure during movement of warm air and cold air. A barometer falls when steady rains begin, and it stops falling when temperature rises.
- 13. Cold fronts Is the boundary along the leading edge of a cold air mass pushing out a warm air mass. When cold air mass moves, it pushes and lifts the warm air mass. This warm air mass cools when it reaches high altitude and causes water vapor to condense and form clouds. Cumulonimbus clouds could appear if there is a great difference in temperature between the cold and warm air mass. Cumulonimbus clouds could bring thunderstorms, rain showers, or even tornadoes. The sky will become clear as the cold front passes by and the wind changes its direction. You should be prepared in the sudden change in weather.
- 14. Occluded Fronts Is formed when a cold air mass moves toward each other with warm air between them. The colder air pushes the warm air upward, closing off warm air from the surface. The warm air is lifted above the ground. An occluded front is formed between the boundaries of two cold air masses. Cloud is developed above the occluded front where warm moist air is found. Places in an occluded front will experience steady rains.
- 15. Stationary Fronts Occurs when a boundary between air masses stops advancing. The stationary fronts may remain in the same place for several days. The place in stationary front will experience light wind and precipitation.
- 16. Prevailing Winds Weather patterns in the Philippines are also influenced by prevailing winds. Prevailing winds are winds that blow mostly from a single direction. The prevailing winds in the Philippines are the southwest monsoon or habagat and northeast Monsoon or amihan.
- 17. The southwest monsoon occurs from May to October, and the northeast monsoon is from November to early May. For most of the country, the dry season is during amihan, and the wet season is during habagat. The wet season starts in June and reaches its peak in July and September. However, weather patters change. Sometimes, rain arrives late and lasts up to December. In some regions of the Philippines, the seasons are different. Much of the eastern seaboard, including Southern Leyte, Easter Samar and Southeastern Luzon, the rain is from December to March; and its fairly dry when the rest of the country is raining.
- 19. QUESTIONS 1. What are the four types of fronts in the country? 2. What is formed at the center of the most rapid winds at the top of the troposphere? 3. What are the two prevailing winds in the Philippines? 4. What are the most common precipitation types in the Philippines? 5. What is the measure of the moisture present in the air called?
- 20. • ANSWERS ON THE NEXT SLIDE
- 21. ANSWERS: 1. Cold, warm, occluded, stationary fronts 2. jet stream 3. Southwest monsoon or habagat and Northeast monsoon or amihan. 4. rain, drizzle, and hailstones 5. Humidity