Island Climates

• Climatic elements


  The different parts of climate that we measure
• Climate elements


  • Temperature
  • Rainfall
  • Humidity
  • Air pressure
• Climatic factors


  Features in the surrounding environment (at different scales) that cause the specific characteristics of the climatic elements
• Tropical island climates


  • Influenced by their location close to the equator (low latitudes, up to about 20 degrees north and south of the equator)
  • Temperatures are high throughout the year, with the range in temperature throughout the year being quite small
• Rainfall in the tropics


  • Influenced by the prevailing winds (for islands south of the equator, the prevailing winds are called the South East Trade Winds)
  • Influenced by relief (mountains act as barriers to prevailing winds, forcing the air to rise and cool, causing rainfall)
• Orographic rainfall


  Type of rainfall that occurs when winds blow over mountains and the air cools, causing precipitation
• Convectional rainfall


  Type of rainfall caused by the sun's rays heating and evaporating water, which then rises, cools, and condenses into rain
• Depressions


  • Weather systems that develop closer to the equator and move slowly from the north west towards the south east
  • Areas of low pressure characterised by very unsettled weather (windy, rainy, and cloudy)
• Humidity


  The amount of water vapour in the air, which depends on temperatures and sunshine
• Dry season in Sämoa


  • Usually from May to September, affecting the coastal parts of northern and western Upolu and all of Savai‹ (except the south coast)
• Tropical cyclone


  Extreme tropical depression with wind circulation strong enough to cause gale-force winds near its centre, with wind speeds up to 250 km an hour