Tropical cyclones

• they are named according to where they originate

  • North America-> hurricanes
  • China, Japan and Asia-> typhoons
  • Africa-> tropical cyclones
  • Australia-> willy willies
• General characteristics

  1. moves from east to west
  2. driven by tropical easterlies
  3. found between 5-25 N/S
  4. follow an erratic path which is unpredictable
  5. shown by circular isobars closing intense low pressure
  6. diameter 300-500km
• tropical cyclones will never occur at the 30N/S because it is a high pressure zone

  they will never occur at the equator because of the absence of the Coriolis force
• factors necessary for the formation

  sea surface temperatures should be at least 27 degrees Celsius and above

  upper air divergence and lower air convergence

  unstable weather conditions

  latitude should be between 5-25 N/S
• stages of development

  1. initial stage
  2. immature stage
  3. mature stage
  4. dissipating stage
• initial stage

  • pressure at the centre of the cell is above 1000hpa/mb
• immature stage

  • pressure begins to drop below 1000hpa
  • the eye forms
  • hurricane winds form
• Mature stage

  • pressure at the centre is well below 1000hpa(960-980)
  • eye is clearly visible
• Dissipating stage

  • pressure at the centre of the cell increases to rise more than 1000hpa, this occurs because the tropical cyclone has met a landfall and it doesn't have moisture
• tropical cyclones are given name reflecting on how many have occurred in that season, the first will be given a name using the first letter of the alphabet
• associated weather conditions

  eye wall conditions

  • strong winds
  • heavy rainfall caused by thunderstorms formed from cumulonimbus clouds
• eye conditions

  conditions are calm, cool and clear because of the subsiding of air
• at the center of the eye at the ground it will be a low pressure cell and at the upper level it will be a high pressure
• impact on human activities

  • social-> people get injured and die, people get homeless, get water borne diseases and property gets destroyed
  • economic-> soil erosion causes decreases crop production which decreases production in industries and people lose jobs, increase water availability in dams increasing crop production in farms increasing production in industries
  • environmental->crops get destroyed, siltation in dams, animals die n become extinct, houses get destroyed, infrastructure such as roads get destroyed
• management strategies

  • sand bags in river banks
  • early warning systems
  • high lying areas
  • evacuation plans
  • rescue teams
  • stock up resources such as water, food and medical resources like first aid kits