weather disturbances

• weather disturbances - changes in atmospheric conditions and weather patterns
• natural hazard - naturally occurring event that may negatively affect humans
• natural disaster - negative effect of a natural hazard
• caused by decrease in temperature, causing air to to descend, clouds not forming, and winds to diverge = resulting clear skies

  A) high pressure area

  
• area where air pressure is lower than surrounding regions; caused by an increase in temperature causing the air to rise, form clouds, and winds to converge = resulting rainfall

  A) low pressure area

  
• tropical cyclones - low pressure areas that develop over warm tropical waters via condensation
• tropical cyclones are commonly known as:

  • hurricanes - atlantic and east pacific
  • cyclones - indian ocean and south pacific
  • typhoons - pacific ocean
• tornado - violently rotating air column with wind speed of at least 200kph; short lived and greatly devastating
• pagasa classifies typhoons accordingly:

  • low pressure area - develops over the ocean; wind gains speed
  • tropical depression - has winds up to 61kph
  • tropical storm - has winds up to 62 kph to 88 kph; starts becoming circular and can bring about rain
  • severe tropical storm - has winds up to 89 to 117kph
  • typhoon - has winds up to 118kph to 220kph
  • super typhoon - has winds beyond 220kph