19.4

• Tropical countries


  Do not experience the typical four seasons
• The Philippines


  Experiences a wet and dry season
• Wet season (rainy season)


  Experienced from June to October

  
• The Philippines' climate


  • Tropical, hot and humid year-round
  • Divided into a dry season (November to May) and a wet season (June to October)
• Seasons


  Determined based on the amount of energy received by each area on Earth
• Different areas receive a different amount of solar energy due to Earth's tilt
• If it is winter in the northern hemisphere


  It is summer in the southern hemisphere
• Areas near the equator

  Receive almost equal amount of sunlight all year round, making the region "temperate"

  
• This is the reason the Philippines does not experience other seasons
• Seasons in the Philippines


  • Wet season (June to November)
  • Cool dry season (Dec. to Feb.)
  • Hot dry season (March to May)
• Wet season


  • Hosts afternoon and evening thunderstorms almost daily
  • Day-long rains are often the result of other weather systems
• The water brought by the rainfall in wet season


  Makes it ideal for farmers to plant rice
• Hot dry season


  • The amihan wanes and is replaced by the prevailing easterlies, which brings warm, dry air to the country
  • It still rains but only in the eastern part of the Philippines, the rest of the country is hot and dry
• Effects of hot dry season

  • Less water is available for irrigation
  • Drought may occur
  • Fires are common
• During the dry season, humidity is very low causing some watering holes and rivers to dry up, forcing many grazing animals to migrate
• Cold dry season


  • Caused by a cold front, the edge of a cold air mass that forms over Asia during winter
  • The country experiences a drop in temperature and a lack of rainfall, with temperatures that can drop below 20 degrees
• Effects of cold dry season

  • Low temperature may be damaging to crops
  • Fog forms on high-altitude places
• Prevailing winds


  Global networks of wind currents which produce large air masses
• Winds near the equator carry high levels of moisture, while air masses from Asia and Australia are cold and dry
• Air masses


  A volume of air defined by its temperature and water vapour content
• Prevailing winds with high moisture bring storms
• Monsoons


  Seasonal winds formed by continental or oceanic air masses, caused by the difference in temperature between the land breezes and the ocean breezes
• Types of monsoons


  • Northeast monsoon
  • Southwest monsoon
• Southwest monsoon (habagat)


  Blows from the southwest from May to September, coming from a high-pressure air mass over Australia and picking up moisture along the seas where it passes
• Habagat brings warm, moist air to the western parts of the country, resulting in strong winds and rainfall
• Northeast monsoon (amihan)


  Blows from the northeast from October to March, originating from a cold high-pressure area over Asia that forms during winter, traversing fewer waters and bringing lesser rain than habagat
• El Niño–Southern Oscillation (ENSO)


  A large scale oceanographic/meteorological event that forms in the Pacific every 2 to 9 years, weakening the prevailing trade winds and monsoons in the western Pacific
• El Niño is caused by the warming of sea surface temperature in the Pacific and can affect air and sea currents, resulting in reduced rainfall that led to dry spells, droughts and stronger typhoons
• According to observations by PAGASA, the annual mean temperature is increasing, meaning it is getting hotter by the year
• It has been projected that the dry season will become drier while the wet season will become wetter