Tropical Storms

• Formation:

  • Sea temperatures over 27 degrees celcius
  • Thunderstorm cluster
  • Earth's rotation (Coriolis effect)
  • Light wind shear
  • Low pressure
• The earth's rotation, explaining why the trade winds bend

  This is called the?

  A) Coriolis Effect

  
• Tropical storm characteristics:

  • Spin anticlockwise in Northern Hemisphere and clockwise in the Southern Hemisphere
  • Up to 6 miles in height
  • Up to 400 miles wide
  • Travels 10-15 mph
• Why so dangerous?

  • 80-100 storms per year
  • Strong winds
  • Storm surges
• Where are they formed?

  • Over oceans
  • Between 5 and 30 degrees North + South of the equator
  • Concentrated between the tropics
  • Rarely within 5 degrees of the equator
  • Greater concentration in the Northern Hemisphere
• Formation Cycle

  The ocean's warm surface is cooled by strong upward movement of air, forming towering thunderstorm clouds. The Coriolis force powers these clouds, releasing heat and drawing more water from the ocean. As surface winds reach 120km/h, the storm becomes a tropical storm. It develops an eye at its center, with intense weather conditions felt in the outer eye. As it reaches land, the storm's energy supply is cut off, slowing it down and weakening. However, if it reaches warm seas, it may regain strength.
• Storm surge

  Rise in sea level that occurs during tropical storms. The storms produce strong winds that push the water into shore, which can lead to flooding. This makes storm surges very dangerous for coastal regions.
• Saffir Simpson Scale

  Category 1: Winds 74 - 95 mph, lightest storms, minimal damage

  Category 2: Winds 96 - 110 mph, moderate damage eg windows broke

  Category 3: Winds 111 - 129 mph, extensive damage eg property damage, land under 2m flooded up to 8 miles in land

  Category 4: Wind 130 - 156 mph, extreme damage eg beach erosion and roof damage

  Category 5: Winds over 156 mph, catastrophic damage eg loss of life and buildings collapsing.
• How has the distribution of tropical storms changed due to climate change?

  Over the last few decades, sea surface temperatures in the tropics have increased by 0.25 to 0.5 degrees celcius. This may widen distribution as more sea temperatures may be able to exceed 27 degrees celcius, allowing tropical storms to occur outside of the tropics.
• How has the frequency of tropical storms changed due to climate change?

  Computer models have no certainty whether tropical storms will become more frequent. Several models suggest that frequency will reduce but intensity will increase.
• How has the intensity of tropical storms changed due to climate change?

  Scientists have calculated that over the last 30 years tropical storm intensity has increased, appearing to be linked to increase in sea temperatures.