Atmospheric Hazards

• Global Circulation System


  The movement of air around the world
• High pressure


  When air mass descends and presses down on the earth bringing dry calm conditions.
• Low pressure

  When air mass rises creating wet unsettled conditions
• Hadley cell


  A cell of air between the equator and tropics
• Climate zones


  Any of the eight principal zones, roughly marked by lines of latitude, into which the earth can be divided on the basis of climate
• Altitude

  height above sea level
• Condensation

  When water vapour turns into water droplets due to cooling
• Evaporation

  When the heat from the sun turns water from a liquid into a gas - water vapour
• Precipitation


  When water falls to the earth in the form of rain, sleet, snow or hail
• Relief rainfall


  Rainfall that occurs when clouds rise up over mountains
• Storm surge


  When low air pressure raises the level of the ocean, especially as a tropical storm nears the coast line causing many deaths due to drowning
• El Nino


  An event that occurs when weak trade winds blowing east to west allow surface temperatures to increase - less rainfall in Australia - drought
• Drought


  When rainfall is below average for a specific area and reserves of water get used up resulting in water shortages