geography

• Coriolis force

  Causes the deflection of winds, allowing for cyclonic movement
• Tropical cyclone


  • One of the names given when it takes place in the Indian Ocean, alternate names include hurricane in the North Atlantic and typhoon in the North Pacific, develops at the ITCZ but outside the five degrees north and south, associated with the easterly trade winds, requires the Coriolis force for cyclonic movement, intense low pressure storm causing wind and flood damage, can only form under specific conditions, named alphabetically in the season they occur
• Intense low pressure storm

  Causes a lot of wind and flood damage
• Tropical cyclones occur in tropical regions over warm oceans
• Low pressure and vortex formation

  Causes spinning or rotating of the system around the low pressure
• Tropical cyclones move from east to west


  Direction of movement
• Formation of tropical cyclones

  Coriolis force causes deflection of winds, deflection allows for cyclonic movement, low pressure and vortex formation, intense low pressure storm with strong winds and flood damage, main source of energy is latent heat from cooling and condensing air, occurs in tropical regions over warm oceans, moves from east to west
• Main source of energy is latent heat


  Results from cooling and condensing of air, air rising creates low pressure
• Deflection of winds


  Allows for cyclonic movement
• For tropical cyclones to form, there must be rising of air to create low pressure


  They move from east to west
• The temperature must be at least 26.5 degrees Celsius for tropical cyclones to form
• Calm conditions are needed for the vortex to intensify
• Ocean temperatures of 25 degrees Celsius or more are important for tropical cyclones
• Tropical cyclones generally affect the eastern sections of countries
• Moisture feeds into the storm as it rises, driving the storm and making the vortex stronger
• Stages of tropical cyclones

  1. Formative stage with strong updrafts

  2. Rapid rising of air and formation of cumulonimbus clouds
• Conditions necessary for the formation of tropical cyclones

  • Large sea surface area with temperature higher than 26.5 degrees
  • Presence of Coriolis force
  • Small variations in vertical wind speed
  • Low level cyclonic circulation
  • Upper air divergence above the sea
  • Good source of latent heat
  • High humidity and condensation
  • Calm conditions
• High humidity and condensation release enough latent heat of condensation to drive the storm
• Tropical cyclones originate in summer and autumn, mostly in late summer and early autumn
• Latent heat is a good source for tropical cyclones to intensify
• As heat is given off, it makes it hotter and more air rises

  Pressure decreases in the center
• The cyclone can cover distances of more than 300 kilometers, with the whole size of the cyclone being around 500 kilometers. The cyclone moves from east to west in a southwesterly direction from the equator.
• Forward left hand quadrant of the cyclone


  It is the most dangerous and destructive part, with intense winds and cyclones combined. The winds spiral and move in this quadrant, combining with the force of the entire cyclone behind it.
• Cyclone formation

  Temperature above 26.5 degrees celsius and low pressure intensifies, causing air to rise from the surface of the sea. High temperatures cause the air to rise, intensifying the low pressure. The cyclone starts as not very large with no clear eye. The air moves up, creating the eye and spiraling winds. The pressure drops, and the spiraling air movement intensifies. The immature stage sees strong updrafts due to increased temperature from the release of latent heat. The temperature rises, more air rises, pressure decreases, and the eye forms. The vortex becomes more intense, and the pressure in the center drops below a thousand millibars. The mature stage has a very strong pressure gradient, with wind speeds reaching hurricane strength. The calm, clear eye is well developed, with wind speeds piling towards the center at high speeds.
• Eye of the cyclone


  • It is calm, formed in the center, and surrounded by spiraling winds. The pressure in the eye is well below a thousand millibars.
• Low pressure and fast-moving wind over the ocean masses

  Cause a storm surge, which is a huge bulge in the sea water
• Low pressure and fast-moving wind over the ocean masses cause a storm surge


  A huge bulge in the sea water occurs
• When a tropical cyclone moves into cooler subtropical areas, more air subsides, leading to the dissipation of the low pressure in the center
• Dissipating stage of a tropical cyclone

  Pressure starts increasing, cyclone starts to dissipate
• The eye of a tropical cyclone is calm, clear, and has subsiding air, creating clear skies and high humidity
• The eye wall or vortex of a tropical cyclone is associated with rising and cooling of air, resulting in cumulonimbus clouds
• Destructive stage of a tropical cyclone

  Strong winds, torrential rainfall
• Less evaporation and humidity on land compared to the ocean leads to less unstable conditions
• The eye of a tropical cyclone is approximately 25 kilometers in diameter
• When a tropical cyclone moves over land, the wind is slowed down due to friction
• Storm surges lead to further flooding of coastal regions hit by the cyclone
• The extreme low pressure in the center of a tropical cyclone drives its intensity
• In the eye of a tropical cyclone, there is generally no rainfall, calm conditions, clear skies, and high humidity
• The diameter of a tropical cyclone is approximately 25 kilometers
• A tropical wave is a trough of low pressure